Using DEMs as Heightfields to Create Realistic Terrain

#1 It's actually Digital Elevation Model ;)

The easiest way to get DEM data into TGE is to import it into a converter of some kind, and export a heightmap.

If you can get the terrain engine to import DEM's natively, that would be pretty cool. ASCII DEM's are just comma or space delimited X Y Z coordinates, there is a binary format, I think it's documented on one of the USGS sites, so you'd need a converter for that as well.

Normalizing DEM's as 256x256x256 heightmaps usually produces really good results, though. Basically, it's taking the XYZ data and normalizing it on the to 256 X, 256 Y (dimensions of the bitmap) and 256 Z (shades of grey in the bitmap), pretty standard in topographic mapping. If your data set isn;t set on a square, then it will stretch or compress (or both) the data a bit in one or both directions. Still useful, and so long as you are not doing topographic analysis, sufficiently accurate :)

I THOUGHT Terragen exported heightmaps as bitmaps, but I haven't do3wnloaded it in a while, and the conversation in the chat room yesterday yielded confusing results from whoever was trying to do it :)

Useful links:
http://www.usna.edu/Users/oceano/pguth/website/microdem.htm

http://tahoe.usgs.gov/viewers.html

This guy has some source code:
http://www.arq.net/~kasten/demtools/

#2 I think terragen generates RAW heightmaps. Paint shop pro can open them :) you need to know the exact dimesions of the file as there isn't a header to tell the software that.

I tried it for a while on my old (shall remain nameless cos I don't like it...) engine, haven't tried any thing in Torque though..

Nick

#3 You will probably find this thread useful: www.garagegames.com/index.php?sec=mg&mod=forums&page=result.thread&qt=6444

And heres a place to get free DEMs from all over the country. www.gisdatadepot.com/dem/demdownload.html

#4 Reading DEMs directly would be a nifty feature though ;)

#5 Can anyone suggest some other websites where I can download FREE DEM data? I've check the links above. Just need more choices, if possible.

Thanks!!!

#6 I was doing a search for importing DEM files and I found that it is very difficult to get the "old" format of DEM files online anywhere. They are all SDTS format now. But I did find a cool tool to convert the new complex SDTS format back to the native DEM (ASCII) format. If you download a DEM from:

http://www.cs.arizona.edu/topovista/sdts2dem/

You may want this tool. It's at:

http://www.cs.arizona.edu/topovista/sdts2dem/

#7 Good to know, thanks.
What should that first link be tho ?

#8 Yeah looks like a copy and paste error ;-)

#9 Sorry about that, it should be:
http://data.geocomm.com/dem/demdownload.html

It's just the link from above.

#10 Good Lord do we all have the same ideas? :)
I was just reading up on these, I was gonna use them for some concept renders I'm making for a potential dev partner.

#11 Cool. There is also a pretty sweet utility called blackart. Can be found at:

Blackart

This utility can read DEMS and render them to bitmaps nicely. It does a lot of stuff that I have not yet had a chance to explore. But I have taken those bitmaps, set them to grayscale in photoshop, and imported them as terrains. It works quite nicely. My problem now is that I'm not a geographer, and I need to retain real-world scale when I import the heighmap...

#12 There is a program out there called Daylon Leveller i believe, it is about 100 bucks but can import all the mentioned file formats above(DEM, USGS STDS, USGS DEM, and many more). It can export to a lot of formats as well. I have used it quite a bit for real world terrain. I just need to get some scale info because the scale is all wrong. Can someone post some info on the size and depth of the bmps that TGE and TSE use to create their terrain so i can try and get the scale correct.