Having trouble with shaders and heightfields and DEMs

[michael222]

Hi everyone,
I was successful in converting a DEM file into a Terragen file and then loaded that into a heightfield shader etc. But along with the downloaded dem file came the large diffuse map that came with the USGS info. I'm really having a hard time putting that tif file into just the area that is the Heightfield that has the DEM info in it. For some reason when I try to add the Image Map Shader, it always ends up shading the planet, and not just the heightfield. As I'm sure you know, the color map from the USGS is very specific and it needs to match the heightfield map perfectly. I'm sure there's a step I'm missing and I'm probably not pushing a button that I need to. Thanks so much in advance. Terragen is a great program!

[bigben]

It partly depends on how you've added the terrain to TG.
If you've added it using the "geog heightfield load" then I'd use the "geog image map shader" for the image.  It may not be a geotiff, in which case it won't position correctly but assuming the image matches the dem then you can copy the coordinates from the heightfield node.

If you've converted the the DEM to TG's TER format then you would use the normal "image map shader" and set the projection to "plan Y" You would then have to manually specify the position and size to match the TER.

[Oshyan]

It sounds like you may be using an old workflow. Terragen 3 supports most DEM formats natively and since Terragen's own TER format does not include georeferencing, it is much harder to line up real-world data with multiple TER files, image maps, etc. Instead we recommend using the Heightfield Geog Load and Geog Image Map Shaders to load the data natively in its *original* format. As I mentioned, Terragen 3 supports a wide variety of standard GIS data formats now. If you're using Terragen 2, we'd strongly recommend upgrading to Terragen 3 if working with GIS data is an important part of your workflow.

- Oshyan

[bigben]

And if you're want to mix multiple data files together you might find merging them in a GIS application first, especially if there are regions of no data in the images.  QGIS is free.  I usually use geotiff (with LZW compression) as an export format for imagery so it automatically georeferences in TG.