Provided by: stilts_3.2-2_all 
NAME
stilts-plot2sky - Draws a sky plot
SYNOPSIS
stilts plot2sky [xpix=<int-value>] [ypix=<int-value>]
[insets=<top>,<left>,<bottom>,<right>] [omode=swing|out|cgi|discard|auto]
[storage=simple|cache|basic-cache] [seq=<suffix>[,...]]
[legend=true|false] [legborder=true|false] [legopaque=true|false]
[legseq=<suffix>[,...]] [legpos=<xfrac,yfrac>] [title=<value>]
[auxmap=<map-name>|<color>-<color>[-<color>...]] [auxclip=<lo>,<hi>]
[auxflip=true|false] [auxquant=<number>]
[auxfunc=log|linear|histogram|histolog|sqrt|square] [auxmin=<number>]
[auxmax=<number>] [auxlabel=<text>] [auxcrowd=<factor>]
[auxwidth=<pixels>] [auxvisible=true|false] [forcebitmap=true|false]
[compositor=0..1] [animate=<table>] [afmt=<in-format>]
[astream=true|false] [acmd=<cmds>] [parallel=<int-value>]
[projection=sin|aitoff|car|car0]
[viewsys=equatorial|galactic|supergalactic|ecliptic]
[reflectlon=true|false] [grid=true|false] [scalebar=true|false]
[labelpos=Auto|External|Internal|Basic|Hybrid|None] [sex=true|false]
[crowd=<number>] [gridcolor=<rrggbb>|red|blue|...]
[labelcolor=<rrggbb>|red|blue|...] [gridaa=true|false]
[texttype=plain|antialias|latex] [fontsize=<int-value>]
[fontstyle=standard|serif|mono] [fontweight=plain|bold|italic|bold_italic]
[clon=<degrees>] [clat=<degrees>] [radius=<degrees>] [zoomfactor=<number>]
[leglabelN=<text>] [layerN=<layer-type> <layerN-specific-params>]
DESCRIPTION
plot2sky draws plots on the celestial sphere. This can be represented in a number of ways,
controlled by the projection parameter; by default the view is of a rotatable sphere seen
from the outside (which approximates to a tangent projection for small regions of the
sky), but Aitoff and Plate Carée projections are also available. A number of options are
also provided for drawing and labelling the grid showing celestial coordinates.
Positional coordinates are specified as lon, lat pairs giving longitude and latitude in
decimal degrees. By default these are represented in the output in the same, unlabelled,
coordinate system. However the command can can also transform between different coordinate
systems if you specify the data and view systems e.g.: plot2sky viewsys=galactic
layer1=mark in1=cat.fits lon1=RA2000 lat1=DEC2000 datasys1=equatorial
Content is added to the plot by specifying one or more plot layers using the layerN
parameter. The N part is a suffix applied to all the parameters affecting a given layer;
any suffix (including the empty string) may be used. Available layers for this plot type
are: mark, size, sizexy, skyvector, skyellipse, skycorr, link2, mark2, poly4, mark4,
polygon, label, contour, skydensity, healpix, skygrid.
OPTIONS
xpix=<int-value>
Size of the output image in the X direction in pixels. This includes space for any
axis labels, padding and other decoration outside the plot area itself. See also
insets.
ypix=<int-value>
Size of the output image in the Y direction in pixels. This includes space for any
axis labels, padding and other decoration outside the plot area itself. See also
insets.
insets=<top>,<left>,<bottom>,<right>
Defines the amount of space in pixels around the actual plotting area. This space
is used for axis labels, and other decorations and any left over forms an empty
border.
The size and position of the actual plotting area is determined by this parameter
along with xpix and ypix.
The value of this parameter is 4 comma separated integers:
<top>,<left>,<bottom>,<right>. Any or all of these values may be left blank, in
which case the corresponding margin will be calculated automatically according to
how much space is required.
omode=swing|out|cgi|discard|auto
Determines how the drawn plot will be output, see SUN/256.
* swing: Plot will be displayed in a window on the screen. This plot is "live";
it can be resized and (except for old-style plots) navigated around with mouse
actions in the same way as plots in TOPCAT.
* out: Plot will be written to a file given by out using the graphics format
given by ofmt.
* cgi: Plot will be written in a way suitable for CGI use direct from a web
server. The output is in the graphics format given by ofmt, preceded by a
suitable "Content-type" declaration.
* discard: Plot is drawn, but discarded. There is no output.
* auto: Behaves as swing or out mode depending on presence of out parameter
storage=simple|cache|basic-cache
Determines the way that data is accessed when constructing the plot. There are two
basic options, cached or not.
If no caching is used (simple) then rows are read sequentially from the specified
input table(s) every time they are required. This generally requires a small memory
footprint (though that can depend on how the table is specified) and makes sense if
the data only needs to be scanned once or perhaps if the table is very large.
If caching is used (cache) then the required data is read once from the specified
input table(s) and cached before any plotting is performed, and plots are done
using this cached data. This may use a significant amount of memory for large
tables but it's usually more sensible (faster) if the data will need to be scanned
multiple times.
The default value is cache if a live plot is being generated (omode=swing), since
in that case the plot needs to be redrawn every time the user performs plot
navigation actions or resizes the window, or if animations are being produced.
Otherwise (e.g. output to a graphics file) the default is simple.
seq=<suffix>[,...]
Contains a comma-separated list of layer suffixes to determine the order in which
layers are drawn on the plot. This can affect which symbol are plotted on top of,
and so potentially obscure, which other ones.
When specifying a plot, multiple layers may be specified, each introduced by a
parameter layer<N>, where <N> is a different (arbitrary) suffix labelling the
layer, and is appended to all the parameters specific to defining that layer.
By default the layers are drawn on the plot in the order in which the layer*
parameters appear on the command line. However if this parameter is specified, each
comma-separated element is interpreted as a layer suffix, giving the ordered list
of layers to plot. Every element of the list must be a suffix with a corresponding
layer parameter, but missing or repeated elements are allowed.
legend=true|false
Whether to draw a legend or not. If no value is supplied, the decision is made
automatically: a legend is drawn only if it would have more than one entry.
legborder=true|false
If true, a line border is drawn around the legend.
legopaque=true|false
If true, the background of the legend is opaque, and the legend obscures any plot
components behind it. Otherwise, it's transparent.
legseq=<suffix>[,...]
Determines which layers are represented in the legend (if present) and in which
order they appear. The legend has a line for each layer label (as determined by the
leglabelN parameter). If multiple layers have the same label, they will contribute
to the same entry in the legend, with style icons plotted over each other. The
value of this parameter is a comma-separated sequence of layer suffixes, which
determines the order in which the legend entries appear. Layers with suffixes
missing from this list do not show up in the legend at all.
If no value is supplied (the default), the sequence is the same as the layer
plotting sequence (see seq).
legpos=<xfrac,yfrac>
Determines the internal position of the legend on the plot. The value is a comma-
separated pair of values giving the X and Y positions of the legend within the
plotting bounds, so for instance "0.5,0.5" will put the legend right in the middle
of the plot. If no value is supplied, the legend will appear outside the plot
boundary.
title=<value>
Text of a title to be displayed at the top of the plot. If null, the default, no
title is shown and there's more space for the graphics.
auxmap=<map-name>|<color>-<color>[-<color>...]
Color map used for Aux axis shading.
A mixed bag of colour ramps are available: inferno, magma, plasma, viridis,
cividis, cubehelix, sron, rainbow, rainbow2, rainbow3, pastel, accent, gnuplot,
gnuplot2, specxby, set1, paired, hotcold, rdbu, piyg, brbg, cyan-magenta, red-blue,
brg, heat, cold, light, greyscale, colour, standard, bugn, bupu, orrd, pubu, purd,
huecl, hue, intensity, rgb_red, rgb_green, rgb_blue, hsv_h, hsv_s, hsv_v, yuv_y,
yuv_u, yuv_v, scale_hsv_s, scale_hsv_v, scale_yuv_y, mask, blacker, whiter,
transparency. Note: many of these, including rainbow-like ones, are frowned upon by
the visualisation community.
You can also construct your own custom colour map by giving a sequence of colour
names separated by minus sign ("-") characters. In this case the ramp is a linear
interpolation between each pair of colours named, using the same syntax as when
specifying a colour value. So for instance "yellow-hotpink-#0000ff" would shade
from yellow via hot pink to blue.
auxclip=<lo>,<hi>
Defines a subrange of the colour ramp to be used for Aux shading. The value is
specified as a (low,high) comma-separated pair of two numbers between 0 and 1.
If the full range 0,1 is used, the whole range of colours specified by the selected
shader will be used. But if for instance a value of 0,0.5 is given, only those
colours at the left hand end of the ramp will be seen.
If the null (default) value is chosen, a default clip will be used. This generally
covers most or all of the range 0-1 but for colour maps which fade to white, a
small proportion of the lower end may be excluded, to ensure that all the colours
are visually distinguishable from a white background. This default is usually a
good idea if the colour map is being used with something like a scatter plot, where
markers are plotted against a white background. However, for something like a
density map when the whole plotting area is tiled with colours from the map, it may
be better to supply the whole range 0,1 explicitly.
auxflip=true|false
If true, the colour map on the Aux axis will be reversed.
auxquant=<number>
Allows the colour map used for the Aux axis to be quantised. If an integer value N
is chosen then the colour map will be viewed as N discrete evenly-spaced levels, so
that only N different colours will appear in the plot. This can be used to generate
a contour-like effect, and may make it easier to trace the boundaries of regions of
interest by eye.
If left blank, the colour map is nominally continuous (though in practice it may be
quantised to a medium-sized number like 256).
auxfunc=log|linear|histogram|histolog|sqrt|square
Defines the way that values in the Aux range are mapped to the selected colour
ramp.
The available options are:
* log: Logarithmic scaling
* linear: Linear scaling
* histogram: Scaling follows data distribution, with linear axis
* histolog: Scaling follows data distribution, with logarithmic axis
* sqrt: Square root scaling
* square: Square scaling
For all these options, the full range of data values is used, and displayed on the
colour bar if applicable. The Linear, Log, Square and Sqrt options just apply the
named function to the full data range. The histogram options on the other hand use
a scaling function that corresponds to the actual distribution of the data, so that
there are about the same number of points (or pixels, or whatever is being scaled)
of each colour. The histogram options are somewhat more expensive, but can be a
good choice if you are exploring data whose distribution is unknown or not well-
behaved over its min-max range. The Histogram and HistoLog options both assign the
colours in the same way, but they display the colour ramp with linear or
logarithmic annotation respectively; the HistoLog option also ignores non-positive
values.
auxmin=<number>
Minimum value of the data coordinate on the Aux axis. This sets the value before
any subranging is applied. If not supplied, the value is determined from the
plotted data.
auxmax=<number>
Maximum value of the data coordinate on the Aux axis. This sets the value before
any subranging is applied. If not supplied, the value is determined from the
plotted data.
auxlabel=<text>
Sets the label used to annotate the aux axis, if it is visible.
auxcrowd=<factor>
Determines how closely the tick marks are spaced on the Aux axis, if visible. The
default value is 1, meaning normal crowding. Larger values result in more ticks,
and smaller values fewer ticks. Tick marks will not however be spaced so closely
that the labels overlap each other, so to get very closely spaced marks you may
need to reduce the font size as well.
auxwidth=<pixels>
Determines the lateral size of the aux colour ramp, if visible, in pixels.
auxvisible=true|false
Determines whether the aux axis colour ramp is displayed alongside the plot.
If not supplied (the default), the aux axis will be visible when aux shading is
used in any of the plotted layers.
forcebitmap=true|false
Affects whether rendering of the data contents of a plot (though not axis labels
etc) is always done to an intermediate bitmap rather than, where possible, being
painted using graphics primitives. This is a rather arcane setting that may
nevertheless have noticeable effects on the appearance and size of an output
graphics file, as well as plotting time. For some types of plot (e.g. shadingN=auto
or shadingN=density) it will have no effect, since this kind of rendering happens
in any case.
When writing to vector graphics formats (PDF and PostScript), setting it true will
force the data contents to be bitmapped. This may make the output less beautiful
(round markers will no longer be perfectly round), but it may result in a much
smaller file if there are very many data points.
When writing to bitmapped output formats (PNG, GIF, JPEG, ...), it fixes shapes to
be the same as seen on the screen rather than be rendered at the mercy of the
graphics system, which sometimes introduces small distortions.
compositor=0..1
Defines how multiple overplotted partially transparent pixels are combined to form
a resulting colour. The way this is used depends on the details of the specified
plot.
Currently, this parameter takes a "boost" value in the range 0..1. If the value is
zero, saturation semantics are used: RGB colours are added in proporition to their
associated alpha value until the total alpha is saturated (reaches 1), after which
additional pixels have no further effect. For larger boost values, the effect is
similar, but any non-zero alpha in the output is boosted to the given minimum
value. The effect of this is that even very slightly populated pixels can be
visually distinguished from unpopulated ones which may not be the case for
saturation composition.
animate=<table>
If not null, this parameter causes the command to create a sequence of plots
instead of just one. The parameter value is a table with one row for each frame to
be produced. Columns in the table are interpreted as parameters which may take
different values for each frame; the column name is the parameter name, and the
value for a given frame is its value from that row. Animating like this is
considerably more efficient than invoking the STILTS command in a loop.
The location of the animation control table. This may take one of the following
forms:
* A filename.
* A URL.
* The special value "-", meaning standard input. In this case the input format
must be given explicitly using the afmt parameter. Note that not all formats
can be streamed in this way.
* A system command line with either a "<" character at the start, or a "|"
character at the end ("<syscmd" or "syscmd|"). This executes the given pipeline
and reads from its standard output. This will probably only work on unix-like
systems.
In any case, compressed data in one of the supported compression formats (gzip,
Unix compress or bzip2) will be decompressed transparently.
afmt=<in-format>
Specifies the format of the animation control table as specified by parameter
animate. The known formats are listed in SUN/256. This flag can be used if you know
what format your table is in. If it has the special value (auto) (the default),
then an attempt will be made to detect the format of the table automatically. This
cannot always be done correctly however, in which case the program will exit with
an error explaining which formats were attempted.
astream=true|false
If set true, the animation control table specified by the animate parameter will be
read as a stream. It is necessary to give the afmt parameter in this case.
Depending on the required operations and processing mode, this may cause the read
to fail (sometimes it is necessary to read the table more than once). It is not
normally necessary to set this flag; in most cases the data will be streamed
automatically if that is the best thing to do. However it can sometimes result in
less resource usage when processing large files in certain formats (such as
VOTable).
acmd=<cmds>
Specifies processing to be performed on the animation control table as specified by
parameter animate, before any other processing has taken place. The value of this
parameter is one or more of the filter commands described in SUN/256. If more than
one is given, they must be separated by semicolon characters (";"). This parameter
can be repeated multiple times on the same command line to build up a list of
processing steps. The sequence of commands given in this way defines the processing
pipeline which is performed on the table.
Commands may alteratively be supplied in an external file, by using the indirection
character '@'. Thus a value of "@filename" causes the file filename to be read for
a list of filter commands to execute. The commands in the file may be separated by
newline characters and/or semicolons, and lines which are blank or which start with
a '#' character are ignored.
parallel=<int-value>
Determines how many threads will run in parallel if animation output is being
produced. Only used if the animate parameter is supplied. The default value is the
number of processors apparently available to the JVM.
projection=sin|aitoff|car|car0
Sky projection used to display the plot.
The available options are:
* sin: rotatable sphere
* aitoff: Hammer-Aitoff projection
* car: Plate Carree projection (lon/lat on Cartesian axes) with lon=0 at center
* car0: Plate Carree Projection (lon/lat on Cartesian axes) with lon=180 at
center
viewsys=equatorial|galactic|supergalactic|ecliptic
The sky coordinate system used for the generated plot.
Choice of this value goes along with the data coordinate system that may be
specified for plot layers. If unspecified, a generic longitude/latitude system is
used, and all lon/lat coordinates in the plotted data layers are assumed to be in
the same system. If a value is supplied for this parameter, then a sky system must
(implicitly or explicitly) be supplied for each data layer, and the coordinates are
converted from data to view system before being plotted.
The available options are:
* equatorial: J2000 equatorial system
* galactic: IAU 1958 galactic system
* supergalactic: De Vaucouleurs supergalactic system
* ecliptic: ecliptic system based on conversion at 2000.0
reflectlon=true|false
Whether to invert the celestial sphere by displaying the longitude axis increasing
right-to-left rather than left-to-right. It is conventional to display the
celestial sphere in this way because that's what it looks like from the earth, so
the default is true. Set it false to see the sphere from the outside.
grid=true|false
If true, sky coordinate grid lines are drawn on the plot. If false, they are
absent.
scalebar=true|false
If true, a small bar is drawn near the bottom left of the plot annotated with a
distance in degrees, arc minutes or arc seconds, to make it easier to determine the
size of features on the plot by eye.
labelpos=Auto|External|Internal|Basic|Hybrid|None
Controls whether and where the numeric annotations of the lon/lat axes are
displayed. The default option Auto usually does the sensible thing, but other
options exist to force labelling internally or externally to the plot region, or to
remove numeric labels altogether.
The available options are:
* Auto: Uses External or Internal policy according to whether the sky fills the
plot bounds or not
* External: Labels are drawn outside the plot bounds
* Internal: Labels are drawn inside the plot bounds
* Basic: Labels are drawn somewhere near the grid line
* Hybrid: Grid lines are labelled outside the plot bounds where possible, but
inside if they would otherwise be invisible
* None: Axes are not labelled
sex=true|false
If true, grid line labels are written in sexagesimal notation, if false in decimal
degrees.
crowd=<number>
Determines how closely sky grid lines are spaced. The default value is 1, meaning
normal crowding. Larger values result in more grid lines, and smaller values in
fewer grid lines.
gridcolor=<rrggbb>|red|blue|...
The color of the plot grid, given by name or as a hexadecimal RGB value.
The standard plotting colour names are red, blue, green, grey, magenta, cyan,
orange, pink, yellow, black, light_grey, white. However, many other common colour
names (too many to list here) are also understood. The list currently contains
those colour names understood by most web browsers, from AliceBlue to YellowGreen,
listed e.g. in the Extended color keywords section of the CSS3 standard.
Alternatively, a six-digit hexadecimal number RRGGBB may be supplied, optionally
prefixed by "#" or "0x", giving red, green and blue intensities, e.g. "ff00ff",
"#ff00ff" or "0xff00ff" for magenta.
labelcolor=<rrggbb>|red|blue|...
The color of axis labels and other plot annotations, given by name or as a
hexadecimal RGB value.
The standard plotting colour names are red, blue, green, grey, magenta, cyan,
orange, pink, yellow, black, light_grey, white. However, many other common colour
names (too many to list here) are also understood. The list currently contains
those colour names understood by most web browsers, from AliceBlue to YellowGreen,
listed e.g. in the Extended color keywords section of the CSS3 standard.
Alternatively, a six-digit hexadecimal number RRGGBB may be supplied, optionally
prefixed by "#" or "0x", giving red, green and blue intensities, e.g. "ff00ff",
"#ff00ff" or "0xff00ff" for magenta.
gridaa=true|false
If true, grid lines are drawn with antialiasing. Antialiased lines look smoother,
but may take perceptibly longer to draw. Only has any effect for bitmapped output
formats.
texttype=plain|antialias|latex
Determines how to turn label text into characters on the plot. Plain and Antialias
both take the text at face value, but Antialias smooths the characters. LaTeX
interprets the text as LaTeX source code and typesets it accordingly.
When not using LaTeX, antialiased text usually looks nicer, but can be perceptibly
slower to plot. At time of writing, on MacOS antialiased text seems to be required
to stop the writing coming out upside-down for non-horizontal text (MacOS java
bug).
fontsize=<int-value>
Size of the text font in points.
fontstyle=standard|serif|mono
Font style for text.
The available options are:
* standard
* serif
* mono
fontweight=plain|bold|italic|bold_italic
Font weight for text.
The available options are:
* plain
* bold
* italic
* bold_italic
clon=<degrees>
Longitude of the central position of the plot in decimal degrees. Use with clat and
radius. If the center is not specified, the field of view is determined from the
data.
clat=<degrees>
Latitude of the central position of the plot in decimal degrees. Use with clon and
radius. If the center is not specified, the field of view is determined from the
data.
radius=<degrees>
Approximate radius of the plot field of view in degrees. Only used if clon and clat
are also specified.
zoomfactor=<number>
Sets the amount by which the plot view zooms in or out for each unit of mouse wheel
movement. A value of 1 means that mouse wheel zooming has no effect. A higher value
means that the mouse wheel zooms faster and a value nearer 1 means it zooms slower.
Values below 1 are not permitted.
leglabelN=<text>
Sets the presentation label for the layer with a given suffix. This is the text
which is displayed in the legend, if present. Multiple layers may use the same
label, in which case they will be combined to form a single legend entry.
If no value is supplied (the default), the suffix itself is used as the label.
layerN=<layer-type> <layerN-specific-params>
Selects one of the available plot types for layerN. A plot consists of a plotting
surface, set up using the various unsuffixed parameters of the plotting command,
and zero or more plot layers. Each layer is introduced by a parameter with the name
layer<N> where the suffix "<N>" is a label identifying the layer and is appended to
all the parameter names which configure that layer. Suffixes may be any string,
including the empty string.
This parameter may take one of the following values, described in more detail in
SUN/256:
* mark
* size
* sizexy
* skyvector
* skyellipse
* skycorr
* link2
* mark2
* poly4
* mark4
* polygon
* label
* contour
* skydensity
* healpix
* skygrid
Each of these layer types comes with a list of type-specific parameters to define
the details of that layer, including some or all of the following groups:
* input table parameters (e.g. inN, icmdN)
* coordinate params referring to input table columns (e.g. xN, yN)
* layer style parameters (e.g. shadingN, colorN)
Every parameter notionally carries the same suffix N. However, if the suffix is not
present, the application will try looking for a parameter with the same name with
no suffix instead. In this way, if several layers have the same value for a given
parameter (for instance input table), you can supply it using one unsuffixed
parameter to save having to supply several parameters with the same value but
different suffixes.
SEE ALSO
stilts(1)
If the package stilts-doc is installed, the full documentation SUN/256 is available in
HTML format:
file:///usr/share/doc/stilts-doc/sun256/index.html
VERSION
STILTS version 3.2-debian
This is the Debian version of Stilts, which lack the support of some file formats and
network protocols. For differences see
file:///usr/share/doc/stilts/README.Debian
AUTHOR
Mark Taylor (Bristol University)
Mar 2017 STILTS-PLOT2SKY(1)