using Mapserver for on-the-fly raster data?

[Jeff de La Beaujardiere]

Frank Warmerdam wrote:
> If so, it might make sense to create a .vrt "raw file header" for each band
> you want to advertise, and then build your map around these.  

A hidden gem!! I had no idea this VRT capability was available. It 
should get mentioned in the How To for rasters.

VRT certainly looks like it would allow me to avoid pre-extracting data 
from my 6GB raw binary raster files with well-known positioning of each 
"band" in the dataset. I suppose the VRT file(s) are enumerated in 
Mapserver's map file as a LAYER DATA filename?

Unfortunately, I'm not sure it is possible to get the correct 
"colorizing" of each data value. In my case, the data values in the 
input file are arbitrary but must be mapped to a discrete set of colors. 
That is, all values in the range [V_i, V_i+1) are mapped to color and 
opacity RGBA_i.

At present, I have been using IDL (Interactive Data Language) to extract 
the data and render it according to the specified color table, which 
gives me full control of the portrayal (but requires pre-generating images).

-Jeff DLB