TransDEM Forum

G'day geophil,

...as you may be aware, Roland, after a recent re-establishment of a corrupted C Drive, I was forced, by necessity, to re-install TransDEM. As this involved a fresh install of version 2.6 and its updates, on a new hard drive, none of the previous installs and their updates "came with it". As a consequence, I now find myself without the required T:ANE Ground Texture Sets that came with the version 2.5 updates of the program. Am I safe to download and install these version 2.5 updates, as is (in the appropriate bit format, of course) from the website directly into version 2.6.0.1 or must I follow some other method to install the newest versions of the Ground Texture Sets?...

Jerker {:)}

A TransDEM 2.6 clean setup should install all variations of the two ground texture sets, version 2 to 5 for the standard set and version 1 and 2 for the ortho-image set.

TransDEM will never use the sets directly, though. It only applies the mapping. That mapping is built-in for the standard set and can be loaded for a custom set. "TransDEM128_mapping.txt" is the mapping for the ortho-image set, all versions.

G'day geophil,

...so, Roland, if I leave the "use Custom Texture Set" option unchecked in the export dialogue, TransDEM will make use of the built-in mapping for the Topographic set? If I get no textures in my route, I need to install the texture sets in Trainz (as I advise my 'clients' to do in similar circumstances)...

Jerker {:)}

Correct. These mappings translate a colour RGB value to a texture KUID. If you don't set a custom mapping, TransDEM will map to the 20 KUIDs of the TransDEM standard ground texture set.

I adopted the mapping mechanics from HOG, including the mapping file format (I did not reinvent the wheel there).

I don't know how HOG actually applied the mapping. TransDEM delegates this to an octree, one of those stunning algorithms in computer science, which are rather simple to implement but amazingly powerful and efficient in their functionality. Basically, an octree is a binary tree with three dimensions (hence the name, 2^3 = 8), one dimension for each of the primary colours red, green and blue. For each colour given, the octree finds the entry in its tree closest to that colour and returns the associated KUID. The octree algorithm also implements a creation strategy. When you feed it with a large number of colour samples, it will create a colour palette optimized for those samples. The standard TransDEM texture set is optimized for cartography where you have very few colours and only need a small palette. It won't work well for orthoimages, though.

For orthoimages I created that custom set. I illustrated its making in this older post which you possibly remember: viewtopic.php?p=1518#p1518

G'day geophil,

...thanks for that, Roland, I do understand how it all works (and I remember reading the 'article' in the link). I shall continue with the work in the current project...

Jerker {:(}