PICTRANS

Transforms a graphics position from one picture co-ordinate Frame to another

Description:

This application transforms a position on a graphics device from one co-ordinate Frame  to another. The input and output Frames may be chosen freely from the Frames available in the WCS  information stored with the current picture in the AGI graphics database. The transformed position is formatted for display and written to the screen and also to an output parameter.

Usage:

pictrans posin framein [frameout] [device]

Parameters:

DEVICE = DEVICE (Read)
The graphics workstation. [The current graphics device]
EPOCHIN = _DOUBLE (Read)
If a ‘Sky Co-ordinate System’ specification is supplied (using Parameter FRAMEIN) for a celestial co-ordinate system, then an epoch value is needed to qualify it. This is the epoch at which the supplied sky position was 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.
EPOCHOUT = _DOUBLE (Read)
If a ‘Sky Co-ordinate System’ specification is supplied (using Parameter FRAMEOUT) for a celestial co-ordinate system, then an epoch value is needed to qualify it. This is the epoch at which the transformed sky position is required. 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.
FRAMEIN = LITERAL (Read)
A string specifying the co-ordinate Frame in which the input position is supplied (see Parameter POSIN). The string can be one of the following options.

If a null parameter value is supplied, then the current Frame  in the current picture is used. [!]

FRAMEOUT = LITERAL (Read)
A string specifying the co-ordinate Frame in which the transformed position is required. If a null parameter value is supplied, then the current Frame in the picture is used. The string can be one of the following options.

  • A domain name such as SKY, AXIS, PIXEL, GRAPHICS, CURPIC, NDC, BASEPIC.

  • An integer value giving the index of the required Frame within the WCS component.

  • An IRAS90 Sky Co-ordinate System (SCS) values such as "EQUAT(J2000)" (see SUN/163).

If a null parameter value is supplied, then the BASEPIC Frame is used. ["BASEPIC"]

POSIN = LITERAL (Read)
The co-ordinates of the position to be transformed, in the co-ordinate Frame specified by Parameter FRAMEIN (supplying a colon ":" will display details of the required co-ordinate Frame). The position should be supplied as a list of formatted axis values separated by spaces or commas.

Results Parameters

BOUND = _LOGICAL (Write)
BOUND is TRUE when the supplied point lies within the bounds of the current picture.
POSOUT = LITERAL (Write)
The formatted co-ordinates of the transformed position, in the co-ordinate Frame specified by Parameter FRAMEOUT. The position will be stored as a list of formatted axis values separated by spaces.

Examples:

pictrans "100.3,-20.1" framein=pixel
This converts the position (100.3, −20.1), in pixel co-ordinates within the current picture of the current graphics device, to the BASEPIC co-ordinates of that point in the BASE picture.
pictrans "100.3,-20.1" framein=pixel frameout=graphics
This converts the position (100.3, −20.1), in pixel co-ordinates within the current picture of the current graphics device, to the GRAPHICS co-ordinates of that point (i.e. millimetres from the bottom-left corner of the graphics device).
pictrans "10 10" framein=graphics frameout=basepic
This converts the position (10, 10), in graphics co-ordinates (i.e. the point which is 10mm above and to the right of the lower-left corner of the graphics device), into BASEPIC co-ordinates.

Notes:

Related Applications

KAPPA: GDSTATE, PICIN, PICXY.