Two things come to mind, both of which many people have done: 1. Since colormaps like everything else in DX is an object in the data model, generate a specialized colormap externally to DX (you can Import .cm files) or construct it within DX. 2. Modify the data (i.e., via Compute). A simple example is a logarithmic colormap.
Tobias Weissbach <[EMAIL PROTECTED]>@opendx.watson.ibm.com on 02/21/2002 09:12:57 AM Please respond to [email protected] Sent by: [EMAIL PROTECTED] To: [email protected] cc: Subject: Re: [opendx-users] Colormap-Question Chris Pelkie wrote: > > >Hello, > > > >I am generating contour plots with OpenDX where the min and max values > >of the > >colormap does not match the min and max values of the data. (e.g. > >colormap > >range is from 0 to 20, but data values can be lower than 0 and higher > >than 20) > >Is there a possibility to give those out of range data points the > >minimum / maximum > >color of the colormap instead of not coloring the points at all ? There > >is such a feature > >for AutoColor (at least for one limit) but I have to use COLOR and > >COLORMAP. > > > >Thanks for any help ... > > > >Tobias > > Of course. Don't data-drive the Colormap, so it won't auto-reset to a > changing input range, then set whatever min and max you always want. > > Then add two control points to the HUE curve (double-click). Drag one > all the way to the left so you have a vertical line from "good max" > up to "real max". Same for min except drag to right to make a > vertical line. Result is a roughly "S" or "Z" shaped curve (standing > on one end). > > Note that the curve shape will remain but the values it maps to will > change if you data-drive and the range changes. This is rarely > desirable. > -- > Chris Pelkie > Scientific Visualization Producer > 618 Rhodes Hall Cornell Theory Center, Cornell University > Ithaca, NY 14853 Actually that is what I did so far for linear colormaps. But now, I want to use an exponential function for the colormap which will be generated outside dx. I thought about adding extra points for min and max values, but only thinking about this can drive you crazy. This is not so easy as it seems. Thats why I wonder if there is another possibility. I even thought about rewriting the color module, but this is beyond my skills. Any other Ideas ?? Tobias
