Colormap

Category

Special

Function

Produces a color map.

Syntax Available only through the user interface.

Inputs

Name	Type	Default	Description
data	field	none	object used to derive min or max
min	scalar	min of data	minimum of color-map range
max	scalar	max of data	maximum of color-map range
nbins	integer	20	number of bins in the histogram
colormap	field or group	none	RGB color map to be used
opacity	field	none	opacity map to be used
title	string	"Colormap Editor"	title of editor

Outputs

Name	Type	Description
rgb	field	RGB color field
opacity	field	opacity field

Functional Details

This interactive module allows the user to create color maps that are applied to data. Through inputs to the module (either the outputs of other tools or values set in its configuration dialog box), the Colormap Editor can be "data driven." If it is not data driven, then the attributes (such as min and max) are taken from values set by the user in the Colormap Editor.

Note: The Colormap Editor itself is invoked by double-clicking on the module's icon in the VPE window. The module's configuration dialog box is accessed from the Edit pull-down menu in the same window.

data	input can be used to derive the minimum and maximum values in the color and opacity maps. If this parameter is specified, a histogram of the "data" component becomes available in the Colormap Editor.
min	sets the minimum value used in the color and opacity maps. If this parameter is specified, it overrides the minimum value set by data. If neither min nor data is specified, the value is set in the minimum field of the Colormap Editor dialog box.
max	sets the maximum value in the color and opacity maps. If this parameter is specified, it overrides the maximum value set by data. If neither max nor data is specified, the value is set in the maximum field of the Colormap Editor dialog box.
nbins	specifies the number of data bins in the histogram displayed by the Colormap Editor. A value of 0 indicates that the histogram should not be computed. The histogram is accessible through the Axis Display in the Options pull-down menu in the Colormap Editor.
colormap	specifies the color map used to initialize the color-map portion of the Colormap Editor. For example, the map may be an imported .cm file, which contains both a color and an opacity map. If this file is passed to the colormap parameter, both maps will be used to initialize the maps in the editor. Alternatively, a simple map field can be passed to the appropriate parameter(s). Note that only the color information of the map is used to initialize the Colormap Editor; the "positions" component of the map (representing the data range to which the colors apply) are ignored. This is to allow a colormap to be used for any input data set which may be passed to the data parameter; the range of the map will be taken from data, rather than from the colormap. If you want to use the actual "positions" of the colormap, then simply use Mark to mark the "positions" component of the colormap, and pass the output of Mark to the data parameter of Colormap.
opacity	specifies the opacity map used to initialize the opacity-map portion of the Colormap Editor.
title	specifies the title of the Colormap Editor window.

Example Visual Programs

UsingColormaps.net
VolumeRendering.net

An example that uses a data-driven Colormap is:

DataDrivenInteractors.net

See Also

 AutoColor,  Color