TransDEM making incredibly large .gnd files

[ThatDonGuy]

I have a USGS DEM image about 110 km high and 90 km wide. When I convert it to a .gnd with MicroDEM and HOG, the resulting file is about 10 MB. However, when I try it with TransDEM, I get a 2 GB file. Am I missing a setting or something? (I pretty much just open the TIF file with "Open DEM", set the grid width UTM to 20m, and then save with "Export & Create: DEM and Ground Textures" with the default settings - note it is 123 baseboards wide and 154 high.)

Speaking of TransDEM, what is the recommended source for overlay (bitmap) files?

 

[Vern]

I think Transdem is correct as try and create a route with bare boards, you will find each one is usually around 200 - 300kb before any placement.

Have you tried using the option in Transdem where you only extract the boards for a set number either side of the route, not the whole area?

Depending on the country, there are various sources for online topographic maps varying from free raster tif downloads to scrollable windowed views which can be "Print-Scrned" and assembled into a coherent whole with a graphics programme. For the US, however, it is worth using the Web Mapping (WMS) feature within Transdem, for which there is a tutorial in the Help files.

 

[geophil]

However, when I try it with TransDEM, I get a 2 GB file. Am I missing a setting or something?

As Vern indicates: Did you apply the route filter? Requires a few polylines to peg-out the course of your route.

BTW, there is no need to re-sample any DEM in TransDEM before exporting to Trainz (unless you want to manually refine the DEM in TransDEM). TransDEM will re-sample the DEM on-the-fly per baseboard created.

Speaking of TransDEM, what is the recommended source for overlay (bitmap) files?

Again, as Vern says: For the US try WMS. There is a tutorial for MS TerraServer in the manual (Durango & Silverton). If the ground textures appear too blurred or fuzzy, you can go for a Map Tile service instead (Google Maps, MS Virtual Earth, now Bing, or Open Street Map). That's the other built-in TransDEM web client. Zoom level for ground textures would be 14.