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EDGE AND CURVE DOCUMENTATION
T A B L E O F C O N T E N T S
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
SECTION PAGE
I INTRODUCTION
I.A THIS DOCUMENT . . . . . . . . . . I-1
I.B EDGE TRACING ALGORITHM . . . . . . . I-1
I.C CURVE FITTING ALGORITHM . . . . . . I-3
I.D CALLING CONVENTIONS . . . . . . . . I-5
I.E LOADING AND COMPILING CONVENTIONS . . . I-6
II MAIN COMMANDS
II.A MAIN COMMAND RESPONSES . . . . . . . II-1
II.B COMMAND DESCRIPTIONS . . . . . . . II-2
II.C FIND - find and trace an object . . . . II-2
II.D FINE - do a fine scan of a previously
traced object . . . . . . . II-4
II.E REJECT - delete data structure for an
object . . . . . . . . . II-6
II.F RELOOK - see if the object is still
there . . . . . . . . . . II-6
II.G COMPACT the data structure . . . . . II-7
II.H FIT straight lines to the object's
edges . . . . . . . . . . II-8
III MINOR COMMANDS
EDGE AND CURVE DOCUMENTATION TABLE OF CONTENTS
III.A INTRODUCTION . . . . . . . . . III-1
III.B DISK - get TV image from disk file . . III-1
III.C GETDATA - get edge follower output . . III-2
III.D GLBDMP - get curve fitter output . . III-2
III.E SETVAL - change a variable . . . . III-4
III.F GETVAL - look at a variable . . . . III-7
III.G XEQ - miscellaneous commands . . . . III-7
IV STRINGS OUTPUT BY PROGRAMS
IV.A INFORMATION OUTPUT . . . . . . . . IV-1
IV.B ERROR OUTPUT . . . . . . . . . . IV-3
V DATA STRUCTURES
V.A EDGE OUTPUT DATA STRUCTURE . . . . . V-1
V.B EDGE INTERNAL DATA STRUCTURE . . . . . V-2
V.C GLOBAL DATA STRUCTURE FROM CURVE . . . V-4
V.D CAMERA TRANSFORM . . . . . . . . . V-6
i
EDGE AND CURVE DOCUMENTATION
SECTION I
_______ _
INTRODUCTION
____________
I.A. THIS DOCUMENT
____ ________
This document is the most complete description of the edge
follower and curve fitter available. These programs are two seperate
jobs, found on SYS,HE as EDGE and CURVE. CURVE normally runs as a
satellite of the edge follower. In this document, EDGE and CURVE are
assumed to be running as subjobs of the hand/eye monitor, unless
otherwise specified. Either job can be run seperately, with or
without the monitor. EDGE funtions the same with or without the
monitor, and basically the same with or without CURVE being available
(except for the commands which reference CURVE); CURVE, however,
behaves differently in each case.
Many variables can be set from the console or other jobs to
control the behavior of EDGE and CURVE. The descriptions for the
commands assume, unless stated otherwise, the settings in effect when
the programs are first started. When a condition can be changed, the
description will state "controlled by " if a variable controls the
condition, or "changed by" if the condition is altered by a command.
A reference will be given to the subsection which describes the
command mentioned; for changing control variables see Section
III.E.
I.B. EDGE TRACING ALGORITHM
____ _______ _________
Edges can be detected by several methods, depending on the
command used. Once an edge has been detected, however, the same
inner loop is used by all commands to follow the edge.
The new Hueckel operator (described in HELIB.KKP[S,DOC]) is
used to track the edge (or line). Its thresholds are set as follows:
DIFF←(1.5[controlled by DIF]*(CASE BITS-3 OF (1.0,
1.0, 2.0, 2.0))↑2 where BITS is the sample size of the
input; 4 for TV input and 3-6 for disk input.
I-1
EDGE AND CURVE DOCUMENTATION INTRODUCTION
CONF←.90 (controlled by CONF)
At each point where the edge has been detected, operator 2 is
moved 1.4 resolution elements (controlled by SPACE) along the edge
and applied at that point. If no edge is found, operator 1 is tried
at the same place. If still no edge is found, one of the following
actions is taken:
1. If the point is outside the field of view of the TV,
the scan is terminated and an attempt is made to scan
from the starting point in the opposite direction, if
that has not already been done. The limits of the TV
field of view are initially set to the limits that the
TV can see (controlled by TMAX, BMAX, RSMAX, and LSMAX)
and edges which extend outside this area are
terminated, rather than followed further (controlled by
SLIM).
2. If the edge was lost, the accomodation routines are
called to adjust the TV clip levels and sensitivity and
then the operator is applied at the point again.
3. If accomodation failed, or the operator indicated a
noisy area, the operator is moved in two concentric
semi-circles centered on the last point found, to try
and pick up the edge further out. If this fails, the
edge has been lost and the program tries to scan in the
opposite director as described in 1 above. It also
checks for any other endpoints near where the edge was
lost. If one is found, the edge is linked to it.
If the edge was found, but at a point where it has recently
been found before, the scan is looping and the actions of 3 above are
carried out. If the new edge point has not been seen before, the
program returns to apply the operator at the next point, after
updating the display (controlled by DISTST) and the local data
structure. All points found during a single trace are stored
together as a single edge segment.
If the point found is near an object already traced, the
current edge segment is linked to that object and the scan
terminated. If the point is found to be near the other endpoint of
the edge segment, the scan is terminated and a closed outline has
been found. If the point is near the endpoint of a different edge
segment, the two edge segments are combined.
If the object has less than 4 edge points when tracing is
I-2
EDGE AND CURVE DOCUMENTATION INTRODUCTION
finished, it is deleted. If any edge segment has less than 3 points,
it is deleted. If the data structure for the object still contains
dangling edges which have only been traced in one direction, the
program tries to trace them in the reverse direction.
The output of this routine is a local data structure
describing the topology of the scene thus far scanned. There is a
circular list of objects each of them pointing to a circular list of
edge segments, each of them pointing to a circular list of edge
points. There is at most one closed edge segment for each object,
denoting an edge with was traced clear around to the starting point.
All other edge segments are flagged with information on why they
terminated. This structure can be passed to the curve fitter (see
Section II.H) or dumped on the disk in a format to be passed to
other jobs (see Section III.C). For a complete description of the
internal data structure see Section V.B.
I.C. CURVE FITTING ALGORITHM
_____ _______ _________
The curve fitter has only one main command and its algorithm
never varies; it can be modified only by changing thresholds. It
makes six passes over the data; one to fit straight lines to the edge
points, and five to clean up the outline obtained.
In the first pass, each edge segment found by the edge
follower for the object is considered separately. If it is not a
closed segment, its entire set of points is used as the first try at
a line segment (often refered to as a line hereafter) and is put in a
stack; otherwise, one point is picked at random and another is picked
to be as far as possible from it. These two points are used to break
the edge segment into two sets of points to be used as initial
guesses for lines, both of which are stacked. The rest of the pass
is a loop. All the points in the current set are used to calculate
the coordinates of the line which makes the best least squares fit of
the points. The error is calculated and if it is less than .2, the
line is accepted and the program goes on to the next set of points,
if any. If the error is two large, the point in the current set with
the maximum distance between it and the line is selected to break the
current set of points into two sets, one of which is stacked and the
program returns to apply the same process to the other set of points.
When a new line is accepted, the intersection of it with the last
line found is considered and the point nearest the intersection in
each set is checked to determine which of the two lines it is closest
to. If it is closest to the line for the other set of points, it is
I-3
EDGE AND CURVE DOCUMENTATION INTRODUCTION
shifted to that set and the line equations of both lines are
recalculated. This continues until there are no shifts. At the
conclusion of this pass, the edge segment has been broken up into one
or more line segments, each of which is a very good fit for the edge
points found in that part of the image. Hopefully, all true corners
have been found, along, usually, with many corners which should not
exist.
The second pass merges short line into longer lines, if
possible. Three consecutive lines are considered at a time. Lines 1
and 2 are combined and a line equation calculated; lines 2 and 3 are
used to calculate a second line equation. The least squares error of
each line is calculated, divided by the number of points in the line
and the two errors compared. If the error of the first line is less
than .7 and less than the error of the second line, it is accepted as
a valid line; otherwise, the two original lines which were combined
are retained. Then lines 2 and 3, if the combined line was not
accepted, or the combined line and line 3 are processed along with
the next adjacent line. The program goes through the complete set of
lines until no lines have been merged in a complete pass through the
set.
In the third pass, all lines less containing less than five
edge points and which are not at the end of one of the original edge
segments is deleted [currently suppressed for complex - KKP] and the
resulting set of lines is intersected to find their exact
intersections. If this intersection is futher than 12 points from
the position of the corner derived from the set of edge points the
lines were formed from, it is rejected as a bad corner. If the
distance between the two vertex points is over 32 a short line is
placed between the ends of the two lines on the assumption that the
curve fitted incorrectly deleted a short line; otherwise, the corner
derived from the edge points is retained. This set of vertex points
is all that is retained for the remainder of the processing.
In pass four the program has a table of all vertices, with
dangling vertices marked. A dangling vertex is one which appears at
the endpoint of only one line. For each dangling vertex, the line
containing that vertex is intersected with all other lines. All
lines whose intersection with the dangling line is within 30 of the
dangling vertex are considered further. Of these lines, the one
whose intersection is closest to the dangling vertex and has the
intersection either on the other line or, if the other line is also
dangling, within 15 of the other dangling vertex, is found. If the
intersection is within 4 of the end of the other line, the dangling
vertex is set equal to that vertex ;otherwise, the intersection is
saved as the new vertex for the dangling line(s) and they are tested
I-4
EDGE AND CURVE DOCUMENTATION INTRODUCTION
in case they are parallel. There is some minor glitching here for
funny cases which occur but the above is correct, just not quite
complete.
In pass five all vertices within 4 of each other are set to
their average coordinates and in pass six all lines of zero length
are deleted.
After the final set of line segments for the object has been
obtained, the program generates the subset of them which may be part
of a closed outline. These are the lines both of whose vertices are
shared by at least two lines, both of which are part of the closed
outline. This set is generated by successive passes through the
lines marking all lines either with dangling vertices or a vertex
shared only by lines with a dangling vertex. When a complete pass
marks no more lines, all lines not marked are part of the closed
outline. The dangling lines are deleted from the internal structure
and put in the global model as a seperate array in case any later
programs want to process them further.
The final step of the curve fitter is to generate the
remainder of the global structure for the object, which is the sole
output of the program (for a description of the structure generated
see Section V.C). To generate the regions of the object, a set
of counters, one for each line, is cleared. Then the program goes
into a loop. If all lines have a count of two, the loop is finished;
otherwise, the vertex which is part of a line with count less than
two and which is the lowest in the TV image of the object is found.
A vertcal line with that vertex as its upper end is assumed.
Starting with that line, an inner loop is executed. The line is found
which has a count less than two and which makes the smallest positive
angle with the original line, moving clockwise from the original
line. This is the first line bounding the region. This line has its
count incremented and the inner loop is repeated starting with this
line. For the rest of the inner loop however, the small
counterclockwise angle is used, except for the first region being
found (this is the 'outside' region of the object). When the
starting vertex is found again the region is finished and the program
returns to look for a new lowest point.
I.D. CALLING CONVENTIONS
_______ ___________
The edge follower and curve fitter accept input either by
means of the user's teletype (TTY) or message procedures (MP) and
I-5
EDGE AND CURVE DOCUMENTATION INTRODUCTION
most commands can be executed from either. If a command functions
differently depending on which way it was called, this will be
pointed out in its description.
Except for the command GLBDMP, all MPs go to the edge
follower, which has as its logical name "EDGE". It acknowledges, but
does not kill, all MPs sent to it. For GLBDMP, the logical name of
the curve fitter is "CURVE". The MP declaration will be given just
before the description of each command; if it is missing, the command
can only by executed from the TTY.
All commands from the TTY go to the edge follower, which uses
___
MPs internally to communicate with the curve fitter if it is
available. The command when typed is generally the same as the
message procedure call, with the parenthesis and commas replaced by
spaces. The exact format will be given before the description of the
command if it can be executed from the TTY.
Many commands have items as parameters. In the case of items
generated by the commands, they are typed as decimal numbers just as
they were typed back at you from the command which generated them
(read about the main commands to understand this). Two special items
are used, EVERY and NIL. These are represented, when typing, as -1
and 0 respectively.
I.E. LOADING AND COMPILING CONVENTIONS
_______ ___ _________ ___________
EDGE and CURVE cannot be loaded by RPG commands; you must run
the loader and give command strings directly to it. The command
strings are:
CURVE with RAID:
GLBLOW[1,3],/VCURVE[SYS,HE]/G
CURVE without RAID:
GLBLOW[1,3],CURVE[SYS,HE]/G
EDGE with RAID:
GLBLOW[1,3],/VCONTRL[SYS,HE]/G
EDGE without RAID:
GLBLOW[1,3],DD[SYS,HE],CONTRL[SYS,HE]/G
I-6
EDGE AND CURVE DOCUMENTATION INTRODUCTION
DD must be loaded, in the last string, in the position shown
or the command decoder will not execute certain commands (GETVAL,
SETVAL, XEQ, and the miscellaneous commands).
If it is necessary to recompile SAIL programs before loading,
this is usually done by COMP /COMP @RPG while logged in on SYS,HE.
If only the files for EDGE and CURVE must be recompiled, they are:
CONTRL, EDGE, MISEDG, INNER, SCANER, CURVE, and MISCUR.
I-7
EDGE AND CURVE DOCUMENTATION
SECTION II
_______ __
MAIN COMMANDS
____ ________
The commands described below activate the main loops of the
edge follower and curve fitter in various ways. If you are doing
simple things they may be all you need. FIND and FINE are explained
in some detail, with examples. Other commands which are variations
of FIND assume you understand it.
II.A. MAIN COMMAND RESPONSES
____ _______ _________
Each of the main commands returns the results of its
execution to the calling job, or TTY, by means of a response message
procedure or output string.
The messsage procedure is declared as
RESPONSE(STRING NAME; INTEGER OBJECT, STATUS)
where NAME is one of the commands. When a 'FIND response' is refered
to below, for example, it means a response with NAME"FIND". OBJECT
is the numeric representation of the item for the object processed,
or of the special item NIL. Note that it is an integer instead of
the item; the item is CVI(OBJECT). This is done so the message
procedure trace of the response will print the number. Then you have
it in case you want to type commands to the edge follower refering to
that object. STATUS tells the calling program what happened,
including unusual or error conditions.
If the command came from the TTY, the response is typed on
the TTY in the form
NAME CVS(OBJECT) CV[O]S(STATUS)
Note that the status may be returned in octal or decimal, depending
on the command. If the item for OBJECT is NIL, the string "NIL" is
substituted for it. See Section II.C and Section II.D for
examples of responses.
II-1
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
II.B. COMMAND DESCRIPTIONS
_______ ____________
Each command description begins with the message procedure
declaration (MP) and typed command format (TTY), if any. The OUTPUT
numbers refer to the strings which may be typed out if the typing
flags (TYP_EDG or TYP_CUR) in the global model are turned on, either
by the calling program or the hand/eye monitor. The strings and
their meaning can be found in Section IV.A. The ERROR numbers
refer to error messages which will be typed irregardless of the
typing flags when an error condition is present which the program
does not feel the calling job can handle. Normally they require
operator intervention; or else a restart of the programs involved.
The error messages and their meaning can be found in Section IV.B.
II.C. FIND - find and trace an object
____ _ ____ ___ _____ __ ______
TTY: FIND ARG
MP: FIND(ITEMVAR ARG);
OUTPUT: 1-18
ERRORS: 1-17, 19-21, 26-27
This command finds an edge and then calls the edge follower
to trace the object (see Section I.B for algorithm). If ARG=NIL, the
command will terminate when at least one object has been found or the
end of the scan is reached. If ARG=EVERY, the entire image will be
scanned to find as many objects as possible. If ARG is anything
else, the result is the same as ARG=NIL, except that if the item
given for ARG appears in global set OLDBLOB, that item will be
associated with the first object found (this feature is mainly for
the RELOOK command); otherwise, a new global item is created for each
object found.
If job CAMERA is running, it is automatically called the
first time through and whenever the camera is moved or focused to
update the camera transform.
The scan starts at one corner of the field of view (limits
controlled by TMAX, BMAX, RSMAX, and LSMAX; starting corner
controlled by XINCR and YINCR) and scans horizontally (direction and
spacing controlled by XINCR), while moving the scan line vertically
(direction and spacing controlled by YINCR). At each point the
program calculates the absolute intensity difference with the last
II-2
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
point on the same horizontal line. If this difference is greater
than a threshold (controlled by TTHRES), Hueckel's operator is
scanned between the two points to find the exact location of the
edge. If no edge has been seen there before, the inner loop is
called to trace the object.
Once the object has been found, the coordinates where it was
first seen are stored and the next FIND command will start scanning
at that point (changed by the START command, see Section III.G).
If the corner diagonally opposite the starting corner is reached, the
scan is reset to the starting corner again.
At the end of the command, a 'FIND' response is returned for
each object traced, giving the item number and status. Some of the
items may have been returned previously. If they appear again, more
edge points have been found for this object. The command always
finishes with a 'FIND' response with ARG=NIL. If this is the only
response, no objects were found. STATUS is given in octal and is
decoded as follows:
-2 control variables were altered incorrectly and are now
inconsistant. No tracing was done.
-1 scan finished (goes with ARG=NIL)
0 a closed curve was traced and nothing else
1 at least one edge being traced was lost due to the
failure of the accomodation routines
2 the trace intersected either the edge it was tracing
other than at the starting point, another edge of the
same object, or an edge of a previously traced object.
In the last case, the objects are merged and the item
number returned is that of the old object.
4 at least one edge went outside the limits of the area
being scanned and SLIM was FALSE (normal case), or it
went outside the TV field of view.
100 no closed outline was found for this object
The status numbers are ORed together. If STATUS<100, then an
outline suitable for SIMPLE has been found. If STATUS≥100, no such
outline is available, although further tracing in the area might find
enough lines to complete the outline, or the curve fitter might be
able to complete it.
II-3
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
EXAMPLE: if you do not understand, read Section I.D and
Section II.A again.
type: FIND 0 (0 equivalent to NIL when typing commands)
program responds, when finished:
FIND 4732 1
FIND 4730 104
FIND NIL
This means two objects were found. The first, 4732, has at least two
edge segments, one of which is a closed outline, and at least one
other was terminated when it was lost. The second object, 4730, has
at least one segment which went outside the field of view, but no
segment is a closed outline.
II.D. FINE - do a fine scan of a previously traced object
____ _ __ _ ____ ____ __ _ __________ ______ ______
TTY: FINE ARG
MP: FINE(ITEMVAR ARG);
OUTPUT: 1-18
ERRORS: 1-17, 19-21, 23, 26-27
The FINE command looks very hard at outlines of objects
already traced to try to find additional edges connected to them.
ARG is the object item to be used; EVERY causes every object found to
be processed unless it had been previously processed. An object
cannot be FINE scanned twice. ARG=NIL is not allowed.
The command places rectangles on the field of view and scans
the entire interior of them using Hueckel's operator with a scan
increment equal to the radius of the operator. If an edge point is
found at a place where none has been seen before, the edge follower
is called to trace it. The trace is allowed to go outside the area
of the rectangle if necessary to complete the scan. If any objects
other than the one the command was processing is found, or
rediscovered, during the scan, it will be added to the list of
objects to be processed. A 'FIND' response is returned for every
object traced. The command finishes with a 'FINE' response. The
object number will be the original item given as ARG, NIL if ARG was
EVERY or the item given did not exist. STATUS is normally 0 and
means nothing.
This commands functions in two modes, depending on whether or
not the curve fitting is available to receive message procedures.
The main difference between the modes is the way the scan rectangles
are set up.
II-4
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
If the curve fitter is not available, for each object to be
processed a rectangle is calculated which entirely covers the object.
After the rectangle is scanned the new limits of the objects are
checked and, if they are now larger due to more edges having been
found, a new rectangle is set up covering the area not covered
previously. This continues until the size of the object does not
increase. Then the same processes is applied to the next object, if
any, waiting, unless that object is wholely contained in one of the
previous rectangles. The program does sometimes scan the same area
more than once but it tries hard to catch the most common cases of
overlap. This mode is the most thorough method of scanning and also
very slow. If the curve fitter is available but you want to force
this mode, set the global flag YES_CUR false. Be sure to set it true
again when you are done or no other program will be able to access
the curve fitter.
If the curve fitter is available, each object to be processed
has its edges fit to straight lines and a list of the corners
created, with corners very close together being counted as one
corner. Then, a rectangle is placed over each corner causing a scan
of the area near that corner; operating on the assumption that any
further edges will meet the current edges at a corner. When all of
them have been checked, the object is passed to then curve fitter
again and any new corners found are checked. This continues until no
new corners are found. Then a rectangle is placed over the entire
objects and a very coarse scan is applied to pick up any long edges
which might have been missed. Normally this is the entire procedure
in this mode. It is possible, however, by means of procedures COLON
and COLOFF to cause this mode to repeat for each object with each
color filter. See Section III.G for more details. Two commands are
recognized in this mode. Both cause the the program to terminate
processing of the current object. NEXT causes the processing of the
next object, if any, to start. CANCEL terminates the command. The
commands are noticed each time the program starts scanning to look
for an edge. If the coarse scan is in progress, they are also
noticed at the begining of each line of the scan.
EXAMPLE: continuing the example given for FIND, if we want to
fine scan the first object found, we type:
FINE 4732
the program responds:
FIND 4730 4
FIND 4726 0
FINE 4732 0
II-5
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
This means no more edges were found for object 4732, since there is
no FIND response for it, but object 4730 was near enough to 4732 to
be seen also and more edge points were found for it, creating a
closed segment. A new object, 4726, was also found, and contains
only a closed segment.
II.E. REJECT - delete data structure for an object
______ _ ______ ____ _________ ___ __ ______
TTY: REJECT ARG
MP: REJECT(ITEMVAR ARG);
OUTPUT: none
ERRORS: none
The object specified by ARG, or all objects if ARG=EVERY, is
deleted, both from the edge followers data structure and from the
portion of the global model created by the edge follower and curve
fitter (see Section V.C for a description of curve fitter data
structure). The item itself is not deleted and is returned with the
'REJECT' response; STATUS will be zero. At the end of REJECT(EVERY),
or if the object given does not exist, the response will have ARG=NIL
and STATUS=-1. As a bonus, the edge follower's display will be
turned off for each object deleted. Once an object has been deleted,
future scanning with the edge follower may cause it to be traced
again. If you do not want the object and do not want to see it
again, do not reject it; just ignore it. If you do not want it but
would be interested in another trace (the current one is bad)
rejected it.
II.F. RELOOK - see if the object is still there
______ _ ___ __ ___ ______ __ _____ _____
TTY: RELOOK ARG
MP: RELOOK(ITEMVAR ARG; INTEGER X,Y);
OUTPUT: 1-18
ERRORS: 1-17, 19-21, 26-27
The object specified by ARG is deleted (by REJECT) and the
edge follower is called to look for it again. The first object found
is assumed to be it. The program sets up a rectangle slightly larger
than the object. If X and Y are zero, or the command was executed
from the TTY, the rectangle is centered at the center of the object;
otherwise it is centered at (X,Y). The scan starts near the middle
of the left side of the rectangle. Only objects inside the rectangle
will be found but, once an object is located, the scan will follow
II-6
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
its edges outside the rectangle if necessary. 'FIND' responses will
be returned for each object found, if any. The final output is the
'RELOOK' response with ARG=NIL and STATUS=-1 if ARG was EVERY (which
is illegal) on entry or no object was found; STATUS=0 otherwise. The
object will be assigned the item in ARG on entry. This is useful if
you think the object may have been moved, or if you know it has been
moved and want to find it, given its approximate position.
II.G. COMPACT the data structure
_______ ___ ____ _________
TTY: COMPACT ARG
MP: COMPACT(ITEMVAR ARG);
OUTPUT: none
ERRORS: 25
This command deletes the edge points from the edge follower's
data structure for this object, which recovers a great deal of core,
and turns off the edge follower's display, if any, for the object if
global flag YES_II is true (the II control program is running and
will take over the display). Future scans b the edge follower will
jump over the area occupied by the object without looking at it,
speeding up the scan. Any new edges which link to a compacted object
will be immediately deleted. The command needs a list of the
object's corner coordinates whih it obtains in one of two ways.
Since the object must be curve fitted before this command can be
executed for it, the curve fitter data structure should exist in the
global model and can be used. If SIMPLE has processed the object, it
has generated a new item to specify the body it has recognized, as
opposed to the object item the edge follower has been using, and some
more global data structure linked to this new item. If the latter
data structure exists it will be used in preference to the curve
fitter's data structure. To retrieve it, the calling program must
have put the body item (from SIMPLE) in global itemvar ITVAR_II; put
NIL or something else safe in it otherwise. The object cannot be
compacted more than once.
ARG=EVERY is illegal for this command. If ARG is an object
in the edge follower's data structure it will be compacted. If ARG
is not an item known to the edge follwer, a new object is generated
in its data structure, with item ARG, and it is compacted. This last
option allows a program using the edge follower to specify an object
it is not to look at while scanning by generating either of the
global data structures mentioned, using the known locations of the
outside corners of the objects, and calling COMPACT with the new
item.
II-7
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
Also, if the TV is moved, call REJECT to get rid of the old
data structure and get the new camera transform. Run the corners, in
TV coordinates, through the new transform to get new TV coordinates,
put them back in the global data structures, and call compact with
the old item number to generate a new compacted structure reflecting
the object's current position in the field of view. Only those
lines, if any, in the current field of view are stored in the data
structure. Lines partially in the field of view will be truncated.
After an object has been compacted, the only edge follower
commands which can refer to it are REJECT and RELOOK. A 'COMPACT'
response is returned for each object compacted with ARG containing
its item number. STATUS contains:
-2 Object ARG has neither association available (ARG=NIL
in response)
-1 Object already compacted or ARG=EVERY on entry (ARG=NIL
in response)
0 object ARG compacted using SIMPLE data structure
1 object ARG compacted using CURVE data structure
II.H. FIT straight lines to the object's edges
___ ________ _____ __ ___ ________ _____
TTY: FIT ARG
MP: FIT(ITEMVAR ARG);
OUTPUT: none
ERRORS: 28-30
If the curve fitter is running and linked to the same global
segment as the edge follower, the edge points for each object will be
passed to it by means of a message procedure and, after
acknowledgment, the lines will be displayed. The user cannot call
the curve fitter directly by a message procedure (unless he can
provide an array of edge points in the proper format (see Section
V.A). If the curve fitter is not available, the edge points for
each object will be dumped on the disk in the same format. Dumping
on the disk can be forced even if the curve fitter is available by
means of the GETDATA command. See Section III.C) for a description
of the GETDATA command, including how the disk file is specified.
The curve fitter can be run by itself off of the files put out by
GETDATA.
II-8
EDGE AND CURVE DOCUMENTATION MAIN COMMANDS
If ARG is an object item, that object will be processed as
described above (see also Section I.C for a description of the curve
fitting heuristics) and a 'FIT' response returned with the item
number and status. If ARG=EVERY, all objects will be processed,
except that the program will not curve fit an object twice unless,
after curve fitting, more edges are traced which connect to the
object. In this case, curve fitting can be done again to include the
new segments which might produce a better, or more complete, fit.
See Section V.C for a description of the data structure produced
by FIT.
The status word in the response will contain one of the
following:
-1 If ARG=EVERY on entry, this means all objects have been
fit. The response for each object has already been
returned. Otherwise, either the object requested did
not exist, has already been curve fit, or had less than
three lines after fitting (in which case the object was
deleted). ARG=NIL in this respose.
0 fit ok
1 fit ok but no closed curve was found. SIMPLE will fail
on this object.
II-9
EDGE AND CURVE DOCUMENTATION
SECTION III
_______ ___
MINOR COMMANDS
_____ ________
III.A. INTRODUCTION
____________
These commands are used to alter various features of the main
commands, set special modes of operation, and cause special dumps of
data structures. Several of the message procedures have, as one of
their arguments, 'REFERENCE BOOLEAN FLAG', which returns an error
flag. This flag will be accessable to the calling program only if
FLAG is a global variable. If the command is executed from the TTY,
the error flag is not needed; the control program yells at you if
there is a mistake by typing "ARG ERR" and what it doesn't like.
III.B. DISK - get TV image from disk file
____ _ ___ __ _____ ____ ____ ____
TTY: DISK FILE_NAME
MP: DISK(STRING FILE_NAME; REFERENCE BOOLEAN FLAG);
OUTPUT: none
ERRORS: 22
This command releases any existing TV buffers and reads in a
disk file, using library routine PICRD, into a TV buffer the exact
length of the data. FILE_NAME is the name of the file and may contain
a project-programmer pair; if none is given, the normal default ppn
is assumed. The file read in must be in the format used by library
routines PICRD and PICWR (created by system program PICTUR or a
similar program). The default values of TMAX ,BMAX, RSMAX and LSMAX
are set from the file's header information. In this mode the TV
camera will never be read. If an edge reaches the edge of the image
read in, it is assumed to be outside the field of view. The TV
accomodation routines are also disabled. If the FINE command is
later executed with the color option on (see Section II.D) and the
file given does not contain a color picture, a new file name is
requested and, if none is given, FINE quits without using color.
FLAG is set false if DISK fails because the file could not be
found, no free disk channels exist, or the picture format was not
III-1
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
correct. If executed from the TTY the string "file_name NOT FOUND"
is typed back. FLAG is TRUE if the file was found all right. If
DISK fails, the edge follower is left in its normal mode, prepared to
accept input from the TV. The command INITTV (see Section III.G)
will force it back into the normal mode if you are done playing with
disk files. DISK can be executed more than once to read in new disk
files; each one replaces the previous file.
III.C. GETDATA - get edge follower output
_______ _ ___ ____ ________ ______
TTY: GETDATA ARG
MP: GETDATA(ITEMVAR ARG; REFERENCE BOOLEAN FLAG);
OUTPUT: none
ERRORS: 24
GETDATA transfers edge points to the calling job. ARG is the
object item whose edge points are desired or EVERY. FLAG is set
false if the object does not exist, or the object has no edge points
(COMPACT command has been executed for it); FLAG is true otherwise.
A real array DAT is created and filled with edge points. See
Section V.A for a descriptin of the format of DAT. DAT will have
bounds 1:MAXCNT, 1:4 where MAXCNT is the number of edge points plus
the number of edge segments.
If the command was given from the TTY, DAT will be written
onto a disk file, in text format, with MAXCNT in the first line,
followed by DAT[I,J], J=1,4 on each line and I=1,2,..,MAXCNT on the
next MAXCNT lines. A file name will be requested. If a camera
transform exists for the object, it is written out last with the
number of lines it needs on the first line, followed by three real
numbers per line. See Section V.D for the format of the camera
transform. If the transform does not exist, the count given is zero
and is on the last line of the file.
If the command was given by a message procedure, the calling
job is sent the message SEND_DATA(MAXCNT,DAT). It must be killed by
the job receiving it and need not be acknowledged.
III.D. GLBDMP - get curve fitter output
______ _ ___ _____ ______ ______
TTY: GLBDMP ARG
MP: GLBDMP(SET ARGS);
III-2
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
ERRORS: ENTER FAILED
GLBDMP dumps the global data structure put out by the curve
fitter (see Section V.C) onto a disk file. The global model is
not changed. If called from the TTY, ARG is the item number of the
object to be dumped, or -1 for the entire data structure, possibly
including objects dumped previously. If called by a message
procedure, ARGS is the set of objects whose structure is to be
dumped, which may be a one item set containing EVERY. EVERY should
not be included in sets containing object items. This message
____ _______
procedure must be sent to CURVE, not EDGE.
_________ ____ __ ____ __ ______ ___ ____
The command will request a file name, including extension,
for the TTY, no matter how it was excuted, which you must give to job
CURVE. All existing data structure for each object will be written
out. The output is commented and should be understandable but below
is the description of the disk file. * denotes the start of a new
line in the file. If you don't want to read all this, there is a
procedure called GLBGET in HELIB which reads these files and restores
the global data structure to its original form.
*integer A, the number of objects followed by A data structures. A
can be zero if you asked for all objects and none exist.
*integer B, the number of vertices for this object, followed by
B lines of vertices. It is zero, as well as all counts below,
if the object does not exist, has no global data structure, or
has no closed regions. In the last case, counts C and D below
will be zero and all data will be in the dangling edge array.
This will happen if the last few passes of the curve fitter were
disabled when it was run.
*real X and Y, the coordinates of a vertex
*integer C, the number of edges for this object, followed by C
lines of edge data
*real L, the length of the edge (always zero from CURVE),
followed by two integers which index into the vertex lines,
above, to specify the endpoints of the edge.
*integer D, the number of regions for this object, followed by D
lines of region information. The first line of region info will
be the background region.
*integer E, the number of vertices for this region,
followed on the same line by E integers which index into
III-3
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
the vertex lines, above, to specify the vertices of the
region, in clockwise order starting with the lowest vertex
in the region.
*integer F, the number of dangling edges, followed by F lines of
edge data. This is zero if all edges are parts of regions.
*real X1 Y1 X2 Y2, the endpoint coordinates of a dangling
line, in random order.
*integer G, the length of the camera transform, followed by G
lines of transform data, three real numbers per line. See
Section V.D for the contents of the transform. G is zero if
there is no transform for this object. Following this is the
start of the data structure for the next object, if any.
III.E. SETVAL - change a variable
______ _ ______ _ ________
TTY: SETVAL NAME VAL
MP: SETVAL(STRING NAME; INTEGER VAL; REFERENCE BOOLEAN FLAG);
SETVAL searches the symbol table for a variable, declared
INTERNAL, called NAME and stores VAL in it. FLAG is false if the
variable is not found. If no variables seen to be present, EDGE was
not loaded properly. No type checking is performed. VAL is normally
an integer. From the TTY only, it will be interpreted as real if a
decimal point appears in it. While any INTERNAL variable can be
changed, many should not be. Below is a table of variables which the
user can safely change, along with their initial value. Some
variables can only take on certain values but the command does no
checking. If limits are given, the edge follower will not run unless
the variables are within the limits. Restarting or reinitializing
EDGE will reset all variables to their initial values. See index for
other references to help explain what these variables do.
VARIABLE INITIAL USE
________ _______ ___
XSTRT 0 X coordinate where the scan starts on next
call of the edge follower's inner loop. If
outside the limits of the scan, it will be
initialized to the proper side of the scan
rectangle according to XINCR.
YSTRT 0 Y coordinate where scan starts on next call.
If outside the scan rectangle, it will be
III-4
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
initialized to the top or bottom of the
rectangle, according to YINCR. If both XSTRT
and YSTRT are zero, the scan is initialized
to a corner of the rectangle. They are
automatically reset to zero when the far
_____________
corner is reached by the scan. Command START
resets both of them at once.
XINCR 8 X increment for the coarse raster scan by
FIND and RELOOK. A positive value scans left
to right; negative values scan right to left.
It must never be zero.
YINCR 8 Y increment for the coarse raster scan for
FIND and RELOOK. A positive value scans up;
negative values scan down. It must never be
zero.
TMAX 10 This and the next three variables define the
limits of the scan rectangle for FIND and
RELOOK. The initial values are the limits of
the TV field of view and these limits should
never be exceeded. They should not be
altered when using the disk image. This is
the top edge.
BMAX 250 Bottom edge. BMAX>TMAX must hold.
LSMAX 10 Left side.
RSMAX 325 Right side. LSMAX<RSMAX must hold.
SLIM 0 If zero, edges will be terminated at the edge
of the scan rectangle; if non-zero, tracing
will continue outside the rectangle.
Scanning will always stop at the limits of
the TV field of view. This affects mainly
FIND and RELOOK; other tracing commands set
this internally the way they want it. Do not
set it non-zero when using disk images or you
will trace garbage.
SPACE 1.4 The increment the operator is moved when
tracing an edge. 1.0≤SPACE≤CIRCLE*1.5, where
CIRCLE is the radius of the operator, is
enforced by the program; anything outside the
limits will be set to the nearest limit.
III-5
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
TOLSCN 3.0 Distance from an edge segment program will
realize it has been seen previously when
scanning for an edge. It should not be
decreased.
TOLTRA 3.0 Distance from an edge segment program will
realize it has been seen previously when
tracing an edge. It should not be decreased.
CONF 0.9 Confidence level for Hueckel operator.
0.85≤CONF<1.0 is recommended.
DIF 1.5 Intensity change for Hueckel operator.
1.5≤DIF recommended.
TTHRES 4 Threshold for difference operator used in
coarse scan for FIND and RELOOK. Threshold
used is (TTHRES + (CASE BITS-3 OF (-4, 0, 4,
4)) MAX 2 where BITS is the sample size in
bits.
TVWID 65 Width of the square read by the TV when
tracing in most of the tracing commands.
Command INITTV must be executed immediately
after changing TVWID to set up the next TV
buffer.
TVCAM 1 TV camera to be read. 2 is the only other
acceptable value (Sierra camera).
DISTST 10 When tracing an edge, the display will be
updated each DISTST points. The larger the
value, the faster the program will run. The
speed vs. value curve is fairly flat above
10, however. The display will be updated at
the end of each edge segment regardless of
the count, if positive. DISTST<0 disables
all displaying.
CLDIFF 1 When accomodating, the program enforces
BCLIP-TCLIP≥CLDIFF. If CLDIFF=7, clip level
accomodation is disabled. If CLDIFF>7,
CLDIFF7. If CLDIFF<0, CLDIFF0.
NODAC 0 If non-zero, the target voltage is frozen at
its current setting and will not be changed
by the accomodation routines, except the auto
target initialization routine.
III-6
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
III.F. GETVAL - look at a variable
______ _ ____ __ _ ________
TTY: GETVAL NAME
MP: none
Variable NAME is looked up in the symbol table and, if found,
its value is typed out either as a REAL or INTEGER (octal and
decimal), depending on the whims of the control program. Any
INTERNAL variable can be accessed this way. Those in the list for
SETVAL are recommended.
III.G. XEQ - miscellaneous commands
___ _ _____________ ________
TTY: NAME
MP: XEQ(STRING NAME; REFERENCE BOOLEAN FLAG);
The symbol table is searched for NAME, which must be declared
INTERNAL, and executes it as a SAIL subroutine with no arguments. If
XEQ was called, FLAG is false if NAME cannot be found. The string
"COM ERR" followed by the command is typed if it was executed from
the TTY. Below is a list of the miscellaneous commands
NAME DESCRIPTION
____ ___________
.GARCO forces garbage collection of edge follower's data
structure (usually happens automatically as needed)
RESTAR reinitializes the edge follower's display, data
structure, image input device (to TV), and control
variables
START resets scan to original starting point
EDGTYP sets global typing flag for EDGE to true to allow
typeout when monitor is not running. Normally off.
CHANGE forces reaccomodation for next scan. To be used when
the scene the TV is looking at is changed.
EDGEON (only on III display) turns on the edge follower
debugging. A point is moved around the scene to show
where the program is looking. Various data is dumped
on disk file EDGn.DBG, where n is the monitor run
number; 0 if no monitor. If you answer "Y" to the
question "DELAY?", the program will stop after each
III-7
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
call of the Hueckel operator and all its output
variables and flags will be displayed, as well as being
dumped on the disk file. <CR> will allow the program
to continue. If you answer anything else to the
question, there will be no stops.
EDGOFF turns off edge follower debugging (normal case)
TIMEIN stores the current clock time and program run time for
EDGE
TIMOUT types elapsed time and run time since TIMEIN was last
called
INITTV set TV input (normal case). For use after DISK command
or TVWID was changed. Creates a TV buffer of at least
500 words, larger if necessary, and forces new
accomodation.
COLON turns on color edge tracing for FINE command.
COLOFF negates COLON (normal case)
DMODE (only on III display with live images) enter special
debugging mode. Procedure INP in HELIB is called to
set the area you want to scan. Then that area is
scanned with the Hueckel operator and an increment
equal to the radius of the operator. At each point the
display described under EDGEON appears and the line
"DMODE: Accom,Exit,Video,Trace,Dump" is typed to remind
you of the responses it likes. Upon typing a <CR>,
possibly preceded by one of the response characters,
the program types "YOPER=", followed by the operator
flag decoded as follows:
-1 outside field of view
0 nothing seen
1 noise seen
2 blew up
3 edge seen
If YOPER>0 the program types "SEEN=" and "PNTR=" with
their values. If SEEN>0 the point has been seen before
as part of an edge, SEEN is the object number and PNTR
points to the point in the data structure. If SEEN=0,
it has not been seen before. Finally, the response
character you typed is decoded as follows:
Y exit from this command
III-8
EDGE AND CURVE DOCUMENTATION MINOR COMMANDS
T call the edge tracing routine to attempt to
trace an edge at the current point.
V send the current TV buffer to DDVID, using
the VIDEO routine in HELIB
A try to accomodate in this area.
D dump the current TV buffer onto the disk,
using library routine PICWR. A file name
will be requested.
Any other response character is ignored. After decoding the
character and taking the specified action, if any, the
program will continue to the next point, except for
responses A and V, which return to process the same
point again.
PTSHOW a square grid is displayed over the normal display. A
number in the center of each square gives the number of
edge points in the area of the image the square covers.
It is displayed to show the complexity of the various
parts of the scene.
ACCON turns on accomodation debugging [details may follower
later]
ACCOFF turns off accomodation debugging (normal case)
III-9
EDGE AND CURVE DOCUMENTATION
SECTION IV
_______ __
STRINGS OUTPUT BY PROGRAMS
_______ ______ __ ________
IV.A. INFORMATION OUTPUT
___________ ______
These strings are typed only if the global typing flag for
EDGE is true.
file EDGE
1 KKP: SCAN OUTSIDE
Edge follower traced an edge to the limit of the field of
view
2 EDGE LOST
Edge follower lost an edge and could not recover it
3 KKP: LOOPING
Edge follower is looping while tracing, usually due to
noise, and cannot recover. The current edge is terminated.
4 KKP: ACCOM FAILED
The accomodation routines were not able to improve edge
contrast when an edge was lost. The current edge is
terminated.
5 KKP: NO POINTS
Tracing routines found no edge point where they were
directed to start tracing.
6 SCAN REVERSED - EDGE
Edge follower terminated tracing of an edge and is now
attempting to extend the other end of the edge, which has
not been previously traced.
7 KKP: OBJECT TOO SMALL
The number of edge points for the object just traced is
below the minimum.
IV-1
EDGE AND CURVE DOCUMENTATION STRINGS OUTPUT BY PROGRAMS
8 DELETED
Normally typed after another string. Indicated that, as a
result of the last string, the current object is being
deleted.
9 KKP: POINT SEEN BEFORE
Tracing for the current object just started and the first
edge point found has been seen before.
10 OPER 1 WON!!
Switching to the smaller Hueckel operator succeeded after
failing with the larger one.
11 SEGMENT CLOSED
While tracing an edge, the opposite end of the edge has been
encountered. We now have a closed outline. The absence of
this message does not necessarily mean that a closed outline
was not found.
12 MERGED SEGMENTS
While tracing an edge, the end of another edge has been
encountered. The two edge segments have been merged.
13 HIT ANOTHER SEGMENT
While tracing an edge, another edge has been encountered,
but not at its end. The current edge is terminated and
linked to the same object as the other edge.
14 FINE CORNER x,y
An edge was lost and never extended. At the end of the
trace for the current object the program notices this and
does a fine scan with the Hueckel operator in the area where
the edge was lost to try to find it again.
file SCANER
15 DAC SET AT n AD=m
Accomodation routines have changed TV sensitivity. You are
given the new DAC setting and corresponding AD reading.
16 AUTO TARGET SET AT n
The autotarget voltage has been recalibrated and you are
given the new DAC setting.
17 lab:TCLIP=m BCLIP=n
Accomodation routine lab has changed the clip levels, which
are given to you.
IV-2
EDGE AND CURVE DOCUMENTATION STRINGS OUTPUT BY PROGRAMS
18 CLIPS RETAINED
Some accomodation routine tried to reaccomodate and failed
to find better settings. The current ones are being
retained.
IV.B. ERROR OUTPUT
_____ ______
These strings inform you of errors and special conditions.
They will always be typed, regardless of the typing switches.
file TVIN
1 TV DATA MISSED - TVIN
Data channel for TV is continuously missing data. Probably a
hardware problem.
2 SYS ERROR - TVIN
System is about to crash. This error message has never been
seen.
3 PARITY ERROR - TVIN
Data channel for TV is continuously getting parity errors.
This is a hardware problem.
4 CAN'T INIT TV. TYPE CHAR TO RETRY
Someone has your TV camera. Go yell at him. Then type
anything at the program to try again.
5 TV IS HUNG
Did you remember to turn on the TV before trying to read it?
file OP
6 ATTEMPT TO TAKE SQRT OF NEGATIVE ARG
The Hueckel operator just blew up.
file FAIPRO
All of these error messages result from the edge follower's data
structure being garbaged. They are all software errors.
IV-3
EDGE AND CURVE DOCUMENTATION STRINGS OUTPUT BY PROGRAMS
7 NO STATUS BITS - PTPNT
8 TWO RIGHT ENDS - GETEND
9 TWO LEFT ENDS - GETEND
10 ONE ONE END - GETEND
11 ENDS OUT OF SEQUENCE - GETEND
file DACO
12 DATA MISSED ON 25 CONSECUTIVE TRIES - AD
The A-D converter is missing data. Either a hardware error
or someone else is using it in spacewar mode.
13 HUNG DEVICE AD
Normally means the PDP-6 is not running. Can also be caused
by spacewar mode users of A-D.
14 DACO TIMED OUT
The A-D reading code is hung up. Spacewar mode users are
bad guys again, probably. Before you feel too smug, let me
point out that this program is also running in spacewar
mode. It does, however, contain special code to insure it
does not damage programs using the A-D with the system code.
It is not too nice to other spacewar mode users.
15 TYPE <CR> TO CONTINUE - ANYTHING ELSE<CR> TO RETRY
This is the second line of all DACO error messages. If you
continue without retrying, the result depends on which
program called it.
file TELL
16 device INITED BY JOB {n/NONE} PPN=pppn
This is a general purpose message put out by many parts of
the program. 'device' is an I/O device (probably TV or AD).
The program tried to initialize the device and found that
someone else had it. 'n' is the number of the job who has
it and 'pppn' is the project-programmer pair the job is
logged in under. NONE for job means the culprit disappeared
before the program could nail him.
file EDGE
IV-4
EDGE AND CURVE DOCUMENTATION STRINGS OUTPUT BY PROGRAMS
17 NO FREE FRAMES
A new display frame is needed for a new object and no frames
are available. The display routines are disabled until new
frames are available.
18 NO DEBUGGING ON THIS DEVICE
Some debugging modes only operate on III displays. You have
tried to use one of them on some other type of console.
19 DPY/DISPLAY TURNED OFF
The display program has overflowed its display buffer. No
more points will be displayed for this object.
20 NO STATUS BITS - REVERSE
Data structure garbaged
21 IGL PNTLST
Data structure garbaged
file MISEDG
22 INPUT FAILED
Attempt to read in a disk image failed. See next message.
23 REQUESTED COLOR NOT IN THIS FILE
You are executing FINE command with color tracing specified
and using disk input. The disk file currently opened does
not contain the needed color image. For both this and the
last message, the program then requests a new file name. If
a null name is given, FINE is terminated and INITTV is
executed.
24 FLAG MISSING - GETDATA
Data structure garbaged.
file INNER
25 GET_BOX SCREWED UP
The COMPACT command failed - program bug.
fileSCANER
26 SENSITIVITY CONTROL IS HUNG - TYPE ANY CHAR TO CONTINUE
The accomodation routines discovered that the sensitivity
IV-5
EDGE AND CURVE DOCUMENTATION STRINGS OUTPUT BY PROGRAMS
cannot be changed. Probably the controls are on manual.
Try to correct and type a character to try again.
27 I1/I2 TOO LARGE/SMALL
Set of four messages. The accomodation routines have set
the clip levels outside the proper range. They are set to
the closest limit of that range.
file CURVE
28 GETMAX LOST BIG
Curve fitter bug
29 SUM ARRAY OVERFLOW
First pass of curve fitter broke object into too many
segments for current array declarations. Recompile with
larger declarations or look at simpler objects.
30 ODAT OVERFLOW
curve fitter output data structure too complex for arrays.
Must be recompiled.
IV-6
EDGE AND CURVE DOCUMENTATION
SECTION V
_______ _
DATA STRUCTURES
____ __________
V.A. EDGE OUTPUT DATA STRUCTURE
____ ______ ____ _________
The data structure produced internally by the edge follower
is converted to an output structure by the GETDATA command and can be
dumped on the disk or passed to another job. It is also generated
and passed to CURVE by means of a message procedure when curve
fitting.
An array, DAT, is created, with bounds 1:MAXCNT,1:4 where
MAXCNT is the number of edge points plus the number of edge segments.
Each segment is together in DAT, preceded by control information,
with the points stored in order around the object in the direction
the edge was initially traced, and one object following another.
DAT[J,1], where J is the first word in DAT for a given segment,
contains the count of the number of coordinates for this segment.
DAT[J,2] is the index in DAT of the start of the next segment, or
zero if this is the last segment. DAT[J,3] is the item number of the
object, if this is the beginning of a new object; zero otherwise.
DAT[J,4] is true if this is a closed segment, of which there is only
one per object; it is false otherwise. Therefore, the next count is
in DAT[DAT[J,2],1]. The coordinates and gradient follow the count
and index, with X in DAT[J+n,1], Y in DAT[J+n,2], the horizontal
component of the gradient in DAT[J+n,3], and the vertical component
of the gradient in DAT[J,n,4], n=1,2,...,DAT[J,1].
J DAT[J,1] DAT[J,2] DAT[J,3] DAT[J,4]
m 3.0 m+4.0 4027.0 0.0
m+1 X1 Y1 CL1 SL1
m+2 X2 Y2 CL2 SL2
m+3 X3 Y3 CL3 SL3
m+4 cnt (m+4)+cnt+1 0.0 0.0
m+5 X11 Y11 CL11 SL11
m+6 X21 Y21 CL21 SL21
etc.
V-1
EDGE AND CURVE DOCUMENTATION DATA STRUCTURES
V.B. EDGE INTERNAL DATA STRUCTURE
____ ________ ____ _________
The following description of the edge follower's internal
data structure is included mainly to aid the author's memory when
debugging it. It makes more sense if you understand LPS. Single
arrows are link pointers. Double arrows are ring pointers.
TOPLST
↓
__________________
| TOP |
| OBJPNT | NULL |
|________________|
OBJLST (last object processed-one for each object)
↓
______________________ OBJPNT
| OBJECT | ↓
| OBJRNG |↔↔↔↔↔↔↔↔↔↔↔↔↔↔↔↔↔
| CORPNT | OUTLIN |
|----------------¬¬¬¬| STATUS BITS (in octal)
|PNTNUM (# of points)|
|DISFRM (frame #) | 1 OR of bits 1-4 from SEGMNT blocks
|OBJNUM (item) |
|TOP (min y coord.) | 10 all segments have been curve fitted
|BOT (max y coord.) | 20 compacted
|LEFT (min x coord.) | 40 inside scanned by FINE or GUNTRACE
|RIGHT (max x coord.)| 100 status returned to calling program
|CAMERA TRANS. (item)| 200 object entirely outside field of view
|____________________|
**** THE STRUCTURE BELOW EXISTS UNTIL COMPACTED ****
SEGLST (last processed - one for each line segment)
↓
_____________ OUTLIN
| SEGMNT | ↓ STATUS BITS
| SEGRNG |↔↔↔↔↔↔↔↔↔
|SEGPNT|NULL| 1,2,4 OR of all POINT status bits 1-4
|___________| 40 segment has been curve fit
V-2
EDGE AND CURVE DOCUMENTATION DATA STRUCTURES
PNTLST (last processed - one for each edge point)
↓
___________ SEGPNT STATUS BITS
| POINT | ↓ 1 lost edge (bit 10 or 20 set also)
| PNTRNG |↔↔↔↔↔↔↔ 2 intersected another edge "
| WORLDR |↔↔↔↔↔↔↔ 4 scan went outside field of view "
|---------| ↑ 10 no right extension of ring
| X | WORLDP 20 no left extension of ring
| Y | (from 40 bit 1 was set and fine scan done in vicinity
|_________| world model)
**** STRUCTURE BELOW EXISTS ONLY AFTER COMPACTING ****
_____________ WORLDP (one for each grid square each
| SEGMNT | ↓ line passes through)
| SEGRNG |↔↔↔↔↔↔
|SEGPNT|NULL|
|___________|
SEGPNT (one for each line)
↓
__________________ CORPNT
| LINE | ↓
| CORRNG |↔↔↔↔↔↔↔↔↔↔
|----------------|
| A (coef. of |
| B line |
| C equation)|
| X1 (first |
| Y1 endpoint) |
| X2 (second |
| Y2 endpoint) |
| D (A↑2+B↑2) |
|________________|
V-3
EDGE AND CURVE DOCUMENTATION DATA STRUCTURES
**** WORLD MODEL ****
PTSEEN TABLE (one entry for each grid square)
↓
______________
| LNK |
|DWN | NULL |
|____________|
|PTSEEN INDEX|
|____________|
¬¬¬¬¬¬¬¬¬¬¬¬¬¬ DWN
| WORLD | ↓ STATUS BITS
| SQRING |↔↔↔↔↔↔↔↔ 128 compacted
| WORLDP|NULL|
|------------|
|OBJECT item |
|____________|
WORLDP points to ring of point blocks,
or a segment and line block if compacted.
V.C. GLOBAL DATA STRUCTURE FROM CURVE
______ ____ _________ ____ _____
The final output of EDGE and CURVE is a data structure in the
global model which describes the objects traced. The GLBDMP command
will dump this data structure onto the disk to save it. Library
routine GLBGET will read in files produced by GLBDMP and put the
structure back in the world model. In the description below $ means
GLOBAL.
For each object, OBJ is the item assigned the object by EDGE
by which you have been refering to the object. For each vertex of
the object
VER ← $ NEW(FOO)
$ MAKE POINT⊗OBJ≡VER
$ DATUM(FOO)[1] ← X coordinate
$ DATUM(FOO)[2] ← Y coordinate
V-4
EDGE AND CURVE DOCUMENTATION DATA STRUCTURES
The only vertex points in these associations are those which bound
closed regions of the object; all other vertex points can be found in
the DANGLE association. If there are no closed regions for this
object, then the POINT, LINE, EDGPT, REGION, PERIMETER, and
BACKGROUND associations described below will not exist.
For each line of the object
LN ← $ NEW(0.0)
$ MAKE LINE⊗OBJ≡LN
$ MAKE ENDPT⊗OBJ≡VER1
$ MAKE ENDPT⊗OBJ≡VER2
where VER1 and VER2 are the vertex items of the endpoints of this
line. Foreach region of the object
REG ← $ NEW
$ MAKE REGION⊗OBJ≡REG
PER ← $ NEW(PHI)
$ MAKE PERIMETER⊗REG≡PER
$ DATUM(PER)[I] ← VERi
where VERi are the i vertices of the region, clockwise, starting with
the lowest in the image. For the background region, REGB, which is
the region bounded by the outermost edges of the object which form
closed regions,
$ MAKE BACKGROUND⊗OBJ≡REGB
Next we have
$MAKE DANGLE⊗OBJ≡$ NEW(ARY)
where ARY is a real array with bounds 1:J,1:4 containing X1, Y1 and
X2, Y2, the coordinates of the endpoints of the J lines of the object
V-5
EDGE AND CURVE DOCUMENTATION DATA STRUCTURES
which are not part of the closed regions. This association does not
exist if J=0. Finally, there is
$ MAKE XFORM⊗OBJ≡$ NEW(CT)
where CT is a real array containing the camera transform. It exists
only if a transform exists for this object. See Section V.D for
a description of the camera transform.
V.D. CAMERA TRANSFORM
______ _________
The camera transform is created by job CAMERA and is normally
found in the global real array CAMERA_MODEL. Whenever EDGE starts
tracing a new object it makes a copy of this array, if it exists, and
links it to the object item. In this way, the camera can be moved
between successive calls on EDGE and each object will still have the
correct transform. The transform contains information on the status
of the cameras when the object was traced and the matrices needed to
convert from the TV coordinate system to the table coordinate system
used by the arm, and back. The transform is a 10x3 array with the
information stored as follows:
1:3,1:3 is the colineation matrix (TABLE → TV)
4,1:3 is the lens center in table coordinates
5,1:2 is the TV coordinates of the point on the
image plane pierced by the axis of the lens.
5,3 is always 1
6:8,1:3 is the inverse colineation matrix (TV →
TABLE)
9,1:3 contain the pot readings, in radians, for
pan, tilt, and focus
10,1 is the camera number
10,2 is the lens number (COHU) or pot reading, in
radians, for the zoom lens (SIERRA)
V-6
EDGE AND CURVE DOCUMENTATION DATA STRUCTURES
10,3 is always 0
V-7
EDGE AND CURVE DOCUMENTATION
INDEX
.GARCO III-7
ACCOFF III-9
ACCON III-9
BMAX I-2, II-2, III-1, III-5
CHANGE III-7
CLDIFF III-6
COLOFF II-5, III-8
COLON II-5, III-8
COMPACT II-7
CONF I-2, III-6
DIF I-1, III-6
DIFF I-1
DISTST I-2, III-6
DMODE III-8
EDGEON III-7
EDGOFF III-8
EDGTYP III-7
EVERY I-6
FIND II-3
FINE II-4, III-1
FIT II-9
GETDATA II-8, III-2, V-1
GETVAL I-7
GLBDMP I-6, III-3, V-4
GLBGET V-4
V-8
EDGE AND CURVE DOCUMENTATION INDEX
HELIB.KKP[S,DOC] I-1
Hueckel operator I-1
INITTV III-8
LSMAX I-2, II-2, III-1, III-5
miscellaneous commands I-7, III-7
NIL I-6, II-1
NODAC III-6
OLDBLOB II-2
PTSHOW III-9
REJECT II-6
RELOOK II-2, II-7
RESPONSE II-1
RESTAR III-7
RSMAX I-2, II-2, III-1, III-5
SETVAL I-7, III-4
SLIM I-2, II-3, III-5
SPACE I-2, III-5
START II-3, III-7
TIMEIN III-8
TIMOUT III-8
TMAX I-2, II-2, III-1, III-5
TOLSCN III-6
TOLTRA III-6
TTHRES II-3, III-6
TVCAM III-6
TVWID III-6
V-9
EDGE AND CURVE DOCUMENTATION INDEX
XEQ I-7, III-7
XINCR II-2, III-5
XSTRT III-4
YINCR II-2, III-5
YSTRT III-4
V-10