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coordsys.settabular - Function

	Package	general
	Module	images
	Tool	coordsys

Set tabular values for the tabular coordinate

Synopsis
settabular(pixel, world, which)

Arguments

pixel	in	Vector of (1-rel) pixel values
		Allowed:	Double vector
		Default:	No change
world	in	Vector of world values
		Allowed:	Double vector
		Default:	No change
which	in	Which Tabular coordinate
		Allowed:	Integer
		Default:	1

Returns
T or fail

Description

When you construct a Coordsys tool, if you include a Tabular Coordinate, it will be linear. This function allows you to replace the Tabular Coordinate by a finite table of values. Coordinate conversions between pixel and world are then done by interpolation (or extrapolation beyond the end). The table of values must be at least of length 2 or an exception will occur.

You may specify a vector of pixel and world values (in the current units of the Tabular Coordinate). These vectors must be the same length. If you leave one of them unset, then the old values are used, but again, ultimately, the pixel and world vectors must be the same length.

The new reference pixel will be the first pixel value. The new reference value will be the first world value.

Presently, there is no way for you to recover the lookup table once you have set it.

If you have more than one Tabular Coordinate, use argument which to specify which one you want to modify.

Example

- cs := coordsys(tabular=T);
- cs.settabular (pixel=[1,10,15,20,100], world=[10,20,50,100,500])

We make a linear Tabular Coordinate. Then overwrite it with a non-linear list of pixel and world values.