Tutorial: Converting a DEM to a heightmap

[tetsuoswrath]

http://forums.nexusmods.com/index.php?/topic/194119-will-somebody-help-me-make-a-map/

 

I'm still trying to get this section of San Diego into game, but I can't get it in the right scale, or with the right amount of detail like my DEM has. Here's a link to the DEM I'm using:

 

http://www.ngdc.noaa.gov/dem/squareCellGrid/download/3542

 

I need this one because it has the roads and foundations for houses. It also has all the minor land elevations I need for the military housing area I mainly need. I'd like to get all of this pic into the game at it's real scale:

 

If anyone can help me get this into FONV I'd appreciate it.

[TrickyVein]

Certainly. I can help you - but you may want to rethink applying 'real' scale to the DEM data. There are a couple of limitations here, resolution being chief among them. Heightmap data in the GECK is limited to a maximum resolution of 1024x1024 pixels per quad, or 16x16 cell area. As each of these cells contains 4096x4096 in game units, the total number of in-game units for each quad of terrain is 65536 units. 65536/1024 = 64 game units. The conversion between Gamebryo's game units and real world metrics is something like 1 unit = 1.3 cm. So 64x1.3 = 83.2cm. Each cell of the DEM data you've linked to is ~ 10m². So each cell of the DEM data would cover 10/0.83m = 12 landscape 'squares' or corresponding pixels within a 1024² heightmap.

 

In other words, you would have to apply a scaling factor of 12 to the DEM data before cropping it into 1024² quads and importing it into the GECK. This makes the in-game resolution of your heighmap effectively 12*64 = 768² units, about the size of a house (like the 'otbldg' models) or a 3x3 sidewalk area. At that point, your landscape would have to extend beyond an area the size of the Mojave Wasteland to include the detail in that image and far, far beyond to make for a convincing landscape (that doesn't just fall off into nothing). This is technically unfeasible as well as undesirable from a creative standpoint.

 

There is no 'quick-fix' scaling factor when dealing with importing DEM data. I've asked the question of Sawyer himself who shared that it was very difficult to decide on the right size for the Mojave Wasteland during development. I am curious to help you however, and can play around with getting some values just right and then you can see if you agree :smile:

Edited December 11, 2012 by TrickyVein

[tetsuoswrath]

I understand it will take a lot. On another forum, a guy did the whole continent of Tamriel for Skyrim. It's detached from the province of Skyrim, but it's still a huge worldspace. I think it's larger than my selected area.

 

I would settle for a smaller part of what I showed you, and use this chunk instead, since it's what I really need for the mod:

If you know how to get at least that section in as close to real scale as possible, I'd gladly accept the aid. Here's a google maps shot with street names if you want to look at the actual area: And here it is in the DEM I got from that Link I posted: You can see the roads, foundations, and the land bridge between Farb and the Youth Center(I used to live there). A problem I keep having with the DEM is that the hills are shaded and when you grayscale it doesn't work right. Also the scale, like you said. I separated the pic from my previous post into 16 quads and it's about right, the hills are too smooth and short though, and no land bridge or small elevation changes like the newer DEM.

 

Thanks for your quick response. This is a personal thing for me. I made a WIP mod of part of the area I want to make for FO3 and it made me want to have the real world height map.

 

Here's a link, the picture isn't what all was done, and the mod is in the tLandscape part of the game(probably wasn't a good idea): http://fallout3.nexusmods.com/mods/12168

 

Now I've been trying to get this into FONV. I'm also modeling the old versions of the houses and buildings in the area. I really really want to get this mod made. Your help is greatly appreciated.

Edited December 11, 2012 by tetsuoswrath

[tetsuoswrath]

Here's the tLandscape heightmap from my mod and a pic of the view from a hill behind my old house. The heightmap's extent is 31, 31. Is that the same as Capital wasteland or Mojave? The third pic is a real scale version of the phase two type one house model(minus textures).

 

 

 

[TrickyVein]

Yeah, that's a DEM with a hillshade effect applied. It's basically garbage. Have you tried following the link I've provided in the tutorial on the first page? There you can find usable elevation data.

 

If you select the Mojave Wasteland worldspace in the heightmap editor you can see for yourself how large it is.

[tetsuoswrath]

I already said the DEM you suggested is the pic from post #41. That grayscale is just to show how much more detailed that DEM is compared to the one you linked. I guess I worded it weird. It can still be grayscaled, it's just the definition gets a little blurry. And is there a way to remove the hillshade effect? I saw that the Mojave Wasteland is 31, 31 as well, but that still shouldn't matter. I've made a mod that extends out past the map and it works. Check this guy Morcroft out: http://www.darkcreations.org/forums/topic/806-common-worldspace-heightmap/ That's well over the 31, 31 norm, so I know it can be done piece by piece.

 

Here's the grayscale from that same DEM:

 

See how it has the Stadium's footprint(That's what I'm calling it), roads, and the land bridge I mentioned?

Edited December 12, 2012 by tetsuoswrath

[tetsuoswrath]

Well I got it into the game, and it retained all the details I wanted it to, only thing is that it's not 1:1 scale. So I separated the heightmap into 16 quads and that made it pretty close to 1:1 scale, but only the center 4 quads load. As I said in another post, BSTamriel is well over 4 quads, so it's possible to get this into the game, but I'm having to get help on the process from the guy who did the Tamriel map. It's going to be great having this in the game.

 

Thanks for posting this thread TV, it's helped me out a bunch. I think you should take a look at the site I linked for DEMs. The one I used was a lot more detailed. Thanks again, and if you know anyway to get 16 quads working in game, I'd appreciate it.

[JarlBrogruf]

Im probably being stupid here, but I'm stuck on the USGS NED downloader. Its asking me for 4 sets of numerical data when latitude and longitude are only 2 sets of data. What do I put in the left and bottom inputs?

[TrickyVein]

It's a range of values. It helps to overextend this range so that you get the coverage you're looking for.

 

For instance, if you were interested in an area contained in the swath at -35,120

 

you'd input -37 to -33 for the latitude

 

and 118 to 123 for the longitude

 

(in decimal degrees, oc)

Edited December 14, 2012 by TrickyVein

[JarlBrogruf]

It's a range of values. It helps to overextend this range so that you get the coverage you're looking for.

 

For instance, if you were interested in an area contained in the swath at -35,120

 

you'd input -37 to -33 for the latitude

 

and 118 to 123 for the longitude

 

Oh ok thank you