Hi Frank >Ytrapaet, > >If you had a 16bit DEM with no color information (such as a normal DTED >for instance) the following command would convert to 8bit by linear scaling >of the min/max to 0-255 without applying any color table. The implicit >color interpretation of the result is greyscale. > > gdal_translate -scale -ot Byte in.dt1 out.tif > >I'm not positive what you did, or what you started with since you didn't >explain.
Sorry for not being clearer: I started off with a a 32bit tif - however, im not sure how I can tell if it has an associated color table. Are there both types of tifs? if so how can I convert from one to the other? What I do know is that when the 32bit elevation model is viewed through ArcGIS, its default setting was on "standard deviation stretch". If I change it to "none", it gives the correct elevation values. However, this seems to only be a display setting; when I converted the 32 to 8bit using gdal_translate (which is the same as your example), the resulting 8bit image did not have any stretching when I viewed it in ArcGIS. However,the conversion did produce my8bit.tif along with my8bit.aux.xml. Normally, when i open images in photoshop, i only plan to loose the georeferencing information, however, it seems that when i open my8bit.tif, i also loose the proper colors. I think this is because the color information is stored in the .aux.xml file, but I dont know how to produce a .tif that is any different (that does not have a .aux.xml file) > Note that raw DEM data has no inherent coloring so it doesn't really mean > anything to say "so that the actual .tif grayscale colors are not > stretched > at all" in this context. I tryed converting my 8bit.tif to 8bit.raw, then back to an 8 bit.tif, but i still always end up with a .aux.xml file even with the .raw route. In other words, any method I try, I always end up with an image that is correctly seen my GIS programs, but incorrectly seen by photoshop. I need the correct grayscale in photoshop so that I can interactively make new RGB color gradients that use the elevation informaiton. I am definitely missing a concept somewhere along the way... The way I see it, its the .aux.xml file about color that I want embedded into the .tif instead. Is this what is meant by "applying a color table"? thanks for helping out -- View this message in context: http://n2.nabble.com/storing-height-information-in-a-tif-rather-the-grayscale-in-the-tif-relying-on-another-file-tp4617873p4620664.html Sent from the GDAL - Dev mailing list archive at Nabble.com. _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
