The different plot2*
commands correspond to
different plot surface geometries.
The different commands come with their own specific
axis configuration parameters.
Some of the plot layer types are specific to certain surface types.
When supplying data from input tables to plot layers,
the coordinate values you need to supply
(and hence the corresponding parameter names)
are determined not by the layer type, but by the surface type.
For instance, point positions for layer N on
a 2-d Cartesian surface (plot2plane
command)
are given using parameters xN
and yN
,
but when plotting to the celestial sphere
(plot2sky
command) you supply
lonN
and latN
).
The following list summarises the available surface types and their corresponding positional coordinates.
plot2plane
)
x
, y
pairs.
Note that this command can also be used to draw histograms.
plot2sky
)
lon
, lat
pairs,
giving longitude and latitude in decimal degrees.
A number of different projections are available,
and conversion between different celestial coordinate systems can
also be performed.
You could use it for other spherical coordinate systems too
(like the surface of a planet).
plot2cube
)
x
, y
, z
triples.
plot2sphere
)
lon
, lat
, r
triples,
giving longitude and latitude in decimal degrees, and radius in
an arbitrary unit.
The plotting surface (space) is similar to Cube,
except that the unit distance is always
the same in all three directions.
plot2corner
)
x1
, x2
, x3
, ... xN
,
up to the number N specified by the nvar
parameter.
plot2time
)
t
, y
pairs.
Time can be represented in input data in various ways;
if sufficient metadata is provided in the input format
the epoch can be determined automatically,
otherwise it may be necessary to specify the time representation
being used.