.help wlpars Jul93 tables
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NAME
wlpars -- Edit the parameter set that determines how WCS labeling 
appears.
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USAGE
wlpars
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DESCRIPTION
These parameters determine the characteristics of plots that are
produced by the various tasks that use the World Coordinate System
(WCS) information from image data. Various
parameters can be set in 'wlpars', including those controlling
the appearance of features such as
major and minor tick marks, the use of grid lines, etc.

Note that this is a pset, not an executable task; it defines a set of
parameters used by other tasks.  Invoking the pset by name runs
`eparam' on the parameter set, allowing you to modify the
parameters.  Alternatively, the parameters may be modified on the
command line by specifying the pset name and parameter name.  For
example, the user can type "wlpars.major_grid=no" to not draw lines
for the major grid, but to include tick marks.  
Parameters can also be edited by
using `eparam' on the calling task (e.g., by typing "eparam wcslab"),
in which case, `wlpars' will appear as one of the task parameters; the
`wlpars' parameters may then be edited by positioning the cursor on
the line containing the pset name and typing ":e".  After editing the
pset parameters, press Control-Z to return to the main task parameter
menu.

Below is a list of areas that explain in more detail what the
parameters in this pset accomplish.  This explanation also occurs in
the help for 'wcslab'.

.ls Axis Specification
For all linear transformations axis 1 and axis 2 specify which axis in
the image WCS is being referred to.
For example in a 2-dimensional image, the FITS image header keywords
CTYPE1, CRPIX1, CRVAL1, CDELT1,
CD1_1, and CD1_2 define the world coordinate transformation for axis 1.
Similarly the FITS image header keywords
CTYPE2, CRPIX2, CRVAL2, CDELT2,
CD2_1, CD2_2, define the world coordinate transformation for axis 2.

THIS RULE DOES NOT APPLY TO THE CELESTIAL plane projection WCSs.
For this type of WCS, axis 1 and axis 2 
always refer to right ascension and declination respectively,
and 'wcslab' assumes that all axis 1 parameters refer to right
ascension and all axis 2 parameters refer to declination, regardless of
which axis in the image WCS actually specifies right ascension and declination.

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.ls Grid Drawing
There are two types of grid lines and tick marks, "major" and
"minor".  The major grid lines and tick marks are the lines or ticks
that will be labeled.  The minor grid lines or tick marks are plotted
between the major marks.  Whether lines or tick marks are drawn is
determined by the boolean parameters 'major_grid' and 'minor_grid'.
If these are set to "yes", lines are drawn; if "no", 
tick marks are drawn.  How the lines
appear is controlled by the parameters 'major_line' and 'minor_line'.

The spacing of minor marks is controlled by the parameters 'axis1_minor'
and 'axis2_minor'. These parameters specify the number of minor marks
that will appear between the major marks along the axis 1
and axis 2 axes.

Spacing of major marks is more complicated.  'wcslab' tries to
present major marks only along "significant values" in the
coordinate system.  For example, if the graph spans several hours of
right ascension,  the interval between major marks will generally be an
hour and the major marks will appear at whole hours within the graph.
If the values chosen by 'wcslab' are unacceptable, the interval and range can
be modified by the parameters 'axis1_int', 'axis1_beg',
'axis1_end' for the 'axis 1', and 'axis2_int', 'axis2_beg',
and 'axis2_end' for 'axis 2'. All three parameters must be specified for
each axis in order for the new values to take affect

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.ls Graph Appearance
'wcslab' supports three types of graph: normal, polar, and near_polar.

A normal graph is the usual Cartesian graph where lines of constant
axis 1 or 2 values cross at least two different sides of the graph.
'wcslab' will, by default, plot a normal type graph for any image that
meets the following criteria: 1)
has no defined WCS, 2) has a linear WCS, and 3) where the sky
projection WCS approximates a Cartesian system.

A polar graph is one in which the north or south pole of the
coordinate system actually appears on the graph.
Lines of constant declination are no longer approximately
straight lines, but are circles that may not intersect any
of the edges of the graph. In this type of graph, axis 1 values
are labeled all the way around the graph. 
Axis 2 values are labeled within the graph
next to each circle.  An attempt is made to label as many circles as
possible.  If you don't like the labeling defaults,
the parameters, 'axis2_dir' and 'justify' can be modified
to control how the labeling is done.
The parameter 'axis2_dir' specifies along which axis 1 value the
axis 2 labels should be written; 'justify' specifies the side of
the value on which the label will appear.

The "near_polar" graph is a cross between the normal graph and the polar
graph.  In this case the pole is not on the graph, but is close enough
to significantly affect the appearance of the plot.  The "near_polar" graph
is handled like a polar graph.

The parameter 'graph_type' can be used to force 'wcslab'
to plot a graph of the type specified, although you may need to
change other 'wlpars' parameters to get good results.
For example, trying to plot a polar graph as
cartesian may producing a strange looking graph.
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.ls Graph Labeling
Due to the variety of graph types that can be plotted (see above), and
the arbitrary rotation that any WCS can have, the task of labeling
the major grid lines in a coherent and pleasing manner is not trivial.

The basic model used is the cartesian or normal graph.  Labels
normally appear on the left and bottom edges of the graph with one side
devoted solely to one of the WCS coordinate axis.  For example, right
ascension might be labeled only along the bottom edge of the graph
and declination only along the left edge, or vice versa. 

If the defaults chosen by the task are unacceptable, the
parameters 'axis1_side' and 'axis2_side', can be used to specify which
side (or sides) the labels for axis 1 and axis 2 will appear.
Either a single side or a list of sides can be specified for either
axis.  If a list is specified, labels will appear on each side listed,
even if the same side appears in both of the parameters.  In this way,
labels can be made to appear on the same side of the graph.
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.ls Label Appearance
Due to coordinate rotations, lines of constant axis 1 or axis 2 value
may not intersect the edges
of the graph perpendicularly.  To help clarify which line belongs to
which label, the labels will be drawn at an angle equal to that of the
line which is being labeled.  If this is not desired, 
the parameter rotate may be set to no, and labels will always appear
"normal", i.e.,  the text will not be rotated in any way.

By default, all labels will be shortened to the smallest unit
needed to indicate the value of the labeled line.  For example, if the
graph spans about 30 seconds of declination, the interval between the
labels will be approximately 5 or 10 seconds. The first label will contain the
full specification, i.e., -22:32:20.  But the rest of the labels will
only be the seconds, i.e., 30, 40, 50.  However, at the change in
minutes, the full format would be used again, -22:33:00, but then
again afterwards only seconds will be displayed, i.e., 10, 20, etc.
If this shortening of labels is undesirable, it
can be turned off by setting the parameter 'full_label = yes'.  This
forces every label to use the full specification.

Finally, the parameter 'label_size' can be used to adjust the size of the
characters used in the axis labels.
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.ls Titles
A graph title may specified using the parameter 'title'. 
If 'title = "imtitle"', a default title constructed from the image name and title
is used. The location and size of the graph title are controlled by
the parameters 'title_side' and 'title_size'.
Similarly the content, placement and size of the axis titles are
controlled by the parameters 'axis1_title', 'axis2_title',
'axis1_title_side', 'axis2_title_side',  and
'axis_title_size'.
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.ls Interactive Cursor
'wcslab' provides a simple cursor readback capability for retrieving
coordinates of objects and saving them in a file.  However, you should
also look at the tasks 'tvmark' and 'rimcursor' for more advance
functionality.

The cursor allows the user to examine
coordinates of specific objects and to make a file containing a
list of coordinates.  For graphic displays, the user has the full cursor
functionality described by 'gcur'.  However, there are a few extra
commands provided for transforming cursor position to celestial
coordinates.  While in cursor mode, striking most lower-case
characters will result in the celestial coordinates of the cursor
position to be displayed on the terminal.

Coordinates can also be written to a file by
striking the lower-case 'm'.  When 'm' is hit, an 'X' is placed on the
display, and the coordinates are written to a coordinate list file.
This file can be specified in two ways.  If you just start hitting
'm', a file called '<imagename>.coord.list' will be created.  You can 
specify a 
different
file with the colon command ":open <filename>".  After opening the 
file, any 
new coordinates marked with the 'm' key are written to the
file.  You can go through as many files as you like.  If a file is
specified that already exists, an attempt is made to read the file.
If it contains coordinate values, those coordinate positions are
displayed as crosses in the window, and any new position marked 
will be appended.

Striking the '?' key will display help concerning these task-specific
commands.  Striking the 'q' key will exit the task.
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.ls Output Formats
Currently, only one coordinate format is supported: all right
ascensions are output in HH:MM:SS (hours:minutes:seconds) format 
and
all declinations are output in DD:MM:SS (degrees:minutes:seconds).  If 
parameters are changed, such as 'axis1_int', they should be
input in the same format.  For the coordinate list files, the first
line of the file begins with the comment character, '#', and displays
the format used in the file.

If the WCS is linear, then output will not be formatted in any special
way; i.e., no assumptions are made about units, etc.
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PARAMETERS
.ls (major_grid = yes) [boolean]
Draw a coordinate grid instead of tick marks at the position of the major
intervals?  

If set to "yes", lines of constant axis1 and axis2 values are drawn.
If set to "no", tick marks will be drawn instead.  Major grid lines and
tick marks will be labeled with the appropriate axis values.
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.ls (minor_grid = no) [boolean]
Draw a coordinate grid instead of tick marks at the position of the
minor intervals?  

If set to "yes", lines of constant axis1 and axis2 values
are drawn between the major grid lines and tick
marks.  If this is set to "no", tick 
marks will be drawn instead. Minor grid lines and  tick
marks are not labeled.
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.ls (dolabel = yes) [boolean]
Label the major grid lines or tick marks?
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.ls (remember = no) [boolean]
Modify the 'wlpars' parameter file when done?  

Setting this to "yes" allows  parameters that may have been calculated
by the task to be written back to the parameter file.  If set to "no",
the default, the parameter file is left untouched by the task.  This is
useful if some slight modification is desired to produce a slightly
different graph.
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.ls (axis1_beg = "") [string]
The lowest value of axis 1 in world coordinates units at which a major
grid line or tick mark will be plotted.  If set to null ('axis1_beg =
""'), 'wcslab'  will compute this quantity.  'axis1_beg' will be
ignored if 'axis1_end' and 'axis1_int' are undefined.
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.ls (axis1_end = "") [string]
The highest value of axis 1 in world coordinate
units at which a major grid line or tick mark will be plotted.
If 'axis1_end = ""', the task will compute this quantity.
'axis1_end' will be ignored if 'axis1_beg' and 'axis1_int' are undefined.
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.ls (axis1_int = "") [string]
The interval in world coordinate units at which
major grid lines and tick marks will be drawn along axis 1.
If 'axis1_int = ""', 'wcslab' will compute this quantity.
'axis1_int' will be ignored if 'axis1_beg' and 'axis1_end' are undefined.
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.ls (axis2_beg = "") [string]
The lowest value of axis 2 in world coordinates units
at which a major grid line or tick mark will be plotted.
If 'axis2_beg = ""', 'wcslab'  will compute this quantity.
'axis2_beg' will be ignored if 'axis2_end' and 'axis2_int' are undefined.
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.ls (axis2_end = "") [string]
The highest value of axis 2 in world coordinate
units at which a major grid line or tick mark will be plotted.
If 'axis2_end = ""', 'wcslab' will compute this quantity.
'axis2_end' will be ignored if 'axis2_beg' and 'axis2_int' are undefined.
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.ls (axis2_int = "") [string]
The interval in world coordinate units at which
major grid lines or tick marks will be drawn along axis 2.
If 'axis2_int = ""', 'wcslab' will compute this quantity.
'axis2_int' will be ignored if 'axis1_beg' and 'axis1_end' are undefined.
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.ls (major_line = "solid") [string, allowed values: solid | 
dotted | dashed | dotdash]

The type of major grid lines to be plotted.
The permitted values are "solid", "dotted", "dashed", and "dotdash".
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.ls (major_tick = .03) [real]
Size of major tick marks relative to the size of the viewport.
By default the major tick marks are .03 times the size of the
viewport.
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.ls (axis1_minor = 5) [integer]
The number of minor grid lines or tick marks that will appear between major 
grid lines or tick marks for axis 1.
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.ls (axis2_minor = 5) [integer]
The number of minor grid lines or tick marks that will appear between major
grid lines or tick marks for axis 2.
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.ls (minor_line = "dotted") [string, allowed values: solid | 
dotted | dashed | dotdash]

The type of minor grid lines to be plotted.
The permitted values are "solid", "dotted", "dashed", and "dotdash".
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.ls (minor_tick = .01) [real]
Size of minor tick marks relative to the size of the viewport.
BY default the minor tick marks are .01 times the size of the
viewport.
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.ls (tick_in = yes) [boolean]
Do tick marks point into instead of away from the graph?
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.ls (axis1_side = "default") [string]
The list of viewport edges, separated by commas, on which to place the axis
1 labels.  If 'axis1_side' is "default", 'wcslab' will choose a side.
'axis1_side' may contain any combination of "left", "right",
"bottom", "top", or "default".
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.ls (axis2_side = "default") [string]
The list of viewport edges, separated by commas, on which to place the axis
2 labels.  If 'axis2_side' is "default", 'wcslab' will choose a side.
'axis2_side' may contain any combination of "left", "right",
"bottom", "top", or "default".
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.ls (axis2_dir = "") [string]
The axis 1 value at which the axis 2 labels will be written for polar graphs. 
If 'axis2_dir' is "", 'wcslab' will compute this number.
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.ls (justify = "default") [string]
The direction with respect to axis 2 along which the axis 2
labels will be drawn from the point they are labeling on polar graphs.
If 'justify = ""', then 'wcslab' will calculate this quantity.  The permitted
values are "default", "left", "right", "top", and "bottom".
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.ls (labout = yes) [boolean]
Draw the labels outside the axes?  

Setting this to "yes", draws labels outside the image viewport.
Otherwise, the axes labels will be drawn inside
the image border.  The latter option is useful if the image fills the
display frame buffer.
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.ls (full_label = no) [boolean]
Always draw all the labels in full format (h:m:s or d:m:s) if the world
coordinate system of the image is in RA and DEC?   

If 'full_label = no', then
only certain axes will be labeled in full format, with the rest
labeled in minutes or seconds, as appropriate.
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.ls (rotate = yes) [boolean]
Permit the labels to rotate ?

If 'rotate = yes', then labels will be written
at an angle to match that of the major grid lines that are being
labeled.  If 'rotate = no', then labels are always written
"normally", that is horizontally. If 'labout = no', then rotate is
set to "no" by default.
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.ls (label_size = 1.0) [real]
The size of the characters used to draw the major grid line labels.
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.ls (title = "imtitle") [string]
The graph title. If 'title = "imtitle"', then a default title containing
the image name and title is created.
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.ls (axis1_title = "") [string]
The title for axis 1. By default no axis 1 title is drawn.
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.ls (axis2_title = "") [string]
The title for axis 2. By default no axis title will be written.
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.ls (title_side = "top") [string, allowed values: top | bottom | 
left | right]

The side of the plot on which to place the title.
The options are "left", "right", "bottom", and "top".
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.ls (axis1_title_side = "default") [string, allowed values: default |
top | bottom | left | right]

The side of the plot on which to place the axis 1 title.
If 'axis1_title_side = "default"', 'wcslab' will choose a side for the title.
The permitted values are "default", "right", "left", "top", and
"bottom".
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.ls (axis2_title_side = "default") [string, allowed values: default |
top | bottom | left | right]

The side of the plot on which to place the axis 2 title.
If 'axis2_title_side = "default"', 'wcslab' will choose a side for the title.
The permitted values are "default", "right", "left", "top", and
"bottom".
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.ls (title_size = 1.0) [real]
The size of characters used to draw the title.
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.ls (axis_title_size = 1.0) [real]
The size of the characters used to draw the axis titles.
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.ls (linecolor = INDEF) [integer]
Color used for drawing lines and tick marks. If this is not specified,
the default color
for the graphics output device will be used.
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.ls (labelcolor = INDEF) [integer]
Color used to write axis labels.  If not specified, the color for the lines
and tickmarks will be used.
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.ls (titlecolor = INDEF) [integer]
Color used to write the plot title. If not specified, the color for the
labels will be used.
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.ls (graph_type = "") [normal | polar | near_polar]
String indicating what type of graph will be drawn.  If empty, the
default, the task will determine the type.   
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.ls (coords) [gcur]
The graphics cursor.
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.ls (image_coord) [imcur]
The image display cursor.
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.ls (version = "16Jun92" ) [string]
The date the current software was installed.
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EXAMPLES
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BUGS
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SEE ALSO
wcslab, cursors, newcont
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