This widget lets the user use and modify colormaps. This can control the
display of volume data or the display of data mapped to a surface.
Volume data brightness is typically controlled from the Brightness sliders
in the Edit Volume Widget. A user may sometimes want to use
the edmap slider instead (or in addition) to those sliders. By far the most
usual reason is to use a custom designed colormap. Once such a map is read
in (see Menu Options below) it is modified via this widget.
Note: the brightness sliders still get applied to the data, but they are
applied first (and they also modify the opacity of the data - brighter voxels
being set to higher opacity). After the brightness sliders are applied, the
edmap slider is applied (but it only affects color, not opacity).
Use of the Sliders
The edmap widget works similar to the standalone edmap program. The right
slider controls which colormap is to be manipulated. The left slider specifies
the data value which gets mapped to the first entry in the specified color
table (e.g., black if it's a grayscale) and the middle slider specifies
the data value which gets mapped to the last entry in the table (e.g., white).
Values between are linearly interpolated into the table. Values below the
left slider get set to the first entry in the color table. Values above the
middle slider get set to the last entry in the table.
This pops up a widget.
This is the file which contains the colormap. It can also be read in from
the command line via the -loadmap option. On an SGI, this colormap is typically created
by using /usr/sbin/interp, /usr/sbin/showmap, and /usr/sbin/savemap. When
maps are saved via savemap, you should specify a 256 wide range of locations
to save. If you save locations 256-511, that is map 1, 512-767 is map 2, etc.
On Linux, use my makemap.pl program to create an ascii text file with
column 1 the map location (eg, 256-511) and columns 2-4 the red,green, and
blue values (0-255).
When you load the map into DAVE, it will go to the same map number.
Click on "Load" to load the specified colormap.
This specifies which map should be used for the volume data. It should be
set to the map number of the map just loaded. Map 15 is the default.
Apply Colormap to Volume Data
When chosen, this causes the colormap in the specified volume map to be
applied to the volume data. Otherwise the default internal maps are used alone.
Objects which are read in via pts files
can have their surface brightness be set to the value of the data voxel which
the surface is passing through (this is done by clicking of the button which
toggles from normal mode to data mode on the Edit Object Properties widget;
see it for more help). This brightness map is stored in map 1 by default.
This entry allows the default to be changed.
NOTE: to change the colormap for Edit->dataplanes specify -Ic 1
(assuming you specify map 1 in loadmap); dataplanes are not
considered volume or surface data. If dataplanes have been displayed
due to -p on the command line, I think -Ic is not necessary.
Copyright 1995 by Lawrence M. Lifshitz and the University of
Massachusetts Medical School. All rights reserved.