Plots a 2-dimensional vector map POLPLOT
The plot is produced within the current graphics database picture, and may be aligned with an existing DATA picture if the existing picture contains suitable co-ordinate Frame information (see parameter CLEAR).
Annotated axes can be produced (see parameter AXES), and the appearance of the axes can be controlled in detail (see parameter STYLE). The axes show co-ordinates in the co-ordinate Frame specified by parameter FRAME.
A key to the vector scale can be displayed to the right of the vector map (see parameter KEY). The appearance and position of this key may be controlled using parameters KEYSTYLE and KEYPOS.
"
Radians"
(case insensitive). The angles
are assumed to be measured anti-clockwise from the reference direction specified in the
catalogue. A list of available column names is displayed if a non-existent column name is given.
See also parameter NEGATE. [ANG] "
Notes"
section below for further details of how these positions are interpreted. [X] "
Notes"
section below for further details of
how these positions are interpreted. [Y] ’
Z’
if the catalogue contains a Z
column, and null (!) otherwise. See also parameter ZAXVAL. [] "
Sky
Co-ordinate System"
specification is supplied (using parameter FRAME) for a celestial
co-ordinate system, then an epoch value is needed to qualify it. This is the epoch at which
the supplied sky positions were determined. It should be given as a decimal years value,
with or without decimal places ("
1996.8"
for example). Such values are interpreted as a
Besselian epoch if less than 1984.0 and as a Julian epoch otherwise. A domain name such as SKY, AXIS, PIXEL, etc. The two "
pseudo-domains"
WORLD and DATA may
be supplied and will be translated into PIXEL and AXIS respectively, so long as the WCS FrameSet in
the catalogue does not contain Frames with these domains.
An integer value giving the index of the required Frame within the WCS component.
A "
Sky Co-ordinate System"
(SCS) value such as EQUAT(J2000) (see section "
Sky Co-ordinate
Systems"
in SUN/95). [!]
CENTRE – the vectors are drawn centred on the corresponding pixel coordinates.
START – the vectors are drawn starting at the corresponding pixel coordinates.
END – the vectors are drawn ending at the corresponding pixel coordinates. ["
Centre"
]
A comma-separated list of strings should be given in which each string is either
an attribute setting, or the name of a text file preceded by an up-arrow character
"
"
.
Such text files should contain further comma-separated lists which will be read and interpreted in the
same manner. Attribute settings are applied in the order in which they occur within the list, with later
settings over-riding any earlier settings given for the same attribute.
Each individual attribute setting should be of the form:
name=value
where name
is the name of a plotting attribute, and
value
is the value to assign to the attribute. Default values will be used for any unspecified attributes. All
attributes will be defaulted if a null value (!) is supplied. See section "
Plotting Attributes"
in SUN/95
for a description of the available attributes. Any unrecognised attributes are ignored (no error is
reported).
By default the key starts with two lines of text, the first being "
Vector scale:"
and the second giving a
numerical value for the scale in units per centimetre. These two lines may be replaced by assigning
alternative text to the Title attribute using this parameter. If no text is required, either assign a blank
value for Title, or set the DrawTitle attribute to zero.
The appearance of the text in the key is controlled using "
String"
attributes (e.g. COLOUR(STRINGS),
FONT(STRINGS), etc - the synonym TEXT can be used in place of STRINGS). Note, the Size attribute
specifies the size of key text relative to the size of the numerical labels on the vector map axes. Thus a
value of 2.0 for Size will result in text which is twice the size of the numerical axis labels. The
appearance of the example vector is controlled using "
Curve"
attributes (e.g. COLOUR(CURVES), etc
- the synonym VECTOR can be used in place of CURVES). The numerical scale value is formatted as
an axis 1 value (using attributes FORMAT(1), DIGITS(1), etc - the synonym SCALE can be used in
place of the value 1). The length of the example vector is formatted as an axis 2 value (using
attribute FORMAT(2), etc - the synonym VECTOR can be used in place of the value 2). The
vertical space between lines in the key can be controlled using attribute TextLabGap. A value
of 1.0 is used if no value is set for this attribute, and produces default vertical spacing.
Values larger than 1.0 increase the vertical space, and values less than 1.0 decrease the
vertical space. [current value]
A comma-separated list of strings should be given in which each string is either
an attribute setting, or the name of a text file preceded by an up-arrow character
"
"
.
Such text files should contain further comma-separated lists which will be read and interpreted in the
same manner. Attribute settings are applied in the order in which they occur within the list, with later
settings over-riding any earlier settings given for the same attribute.
Each individual attribute setting should be of the form:
name=value
where name
is the name of a plotting attribute, and
value
is the value to assign to the attribute. Default values will be used for any unspecified attributes. All
attributes will be defaulted if a null value (!) is supplied. See section "
Plotting Attributes"
in SUN/95
for a description of the available attributes. Any unrecognised attributes are ignored (no error is
reported).
The appearance of the vectors is controlled by the attributes Colour(Curves), Width(Curves), etc (the synonym Vectors may be used in place of Curves). [current value]
"
:"
) for the parameter will result in a description of the current
coordinate Frame being shown. This may help to determine the units in which a value
is expected. The value actually used is the closest available value within the catalogue.
This value is displayed on the screen and included in the default plot title. The ZAXVAL
parameter is only accessed if a null (!) value is supplied for parameter ZCOLVAL. See
also parameter COLZ. "
poltab"
. The magnitudes are taken from column P, the orientations from
column ANG and the coordinates of each vector from columns X and Y. title = My favorite colours |
|
grid = 1 |
|
minticklen = 0 | |
colour(border) = green |
|
colour(grid) = blue |
|
colour(vec) = red |
|
width(border) = 0.05 |
then the title is set to "
My favourite colours"
; a grid is drawn across the plot instead of tick marks
around the edge; the border, grid and vectors are drawn in green, blue and red respectively, and
slightly thicker lines are used to draw the border.
The TITLE parameter in the supplied catalogue is used as the default title for the annotated axes. If the catalogue does not have a TITLE parameter (of it is blank), then the default title is taken from current co-ordinate Frame stored in the WCS component of the catalogue. This default may be over-ridden by specifying a value for the Title attribute using the STYLE parameter.
The columns specified by parameters COLX and COLY should hold coordinates in the "
Base Frame"
of the WCS information stored as an AST FrameSet (see SUN/210) in the supplied catalogue. If the
catalogue has been produced by one of the POLPACK application polvec or polbin, then the Base
Frame will be pixel co-ordinates within the aligned intensity images, and these will be stored in
columns with names "
X"
and "
Y"
. If the catalogue was not created by POLPACK, it may have no
usable WCS information, in which case the supplied positions are mapped linearly onto the screen.
There is one exception to this; if the columns have names RA and DEC then they are assumed to be
equatorial sky coordinates with epoch and equinox specified by the optional catalogue
parameters EPOCH and EQUINOX (defaults are used for these parameters if they are not
present in the catalogue). If the vector map is displayed over an existing DATA picture (i.e.
if CLEAR=NO) then these RA/DEC positions will be aligned with the existing DATA
picture if possible (i.e. if the existing picture has sky coordinate information stored with it).