Tutorial: Converting a DEM to a heightmap

[PossiblyErich]

I've been using Photoshop, and I'm assuming I am doing something wrong here, as the GECK crashes immediately when I try to import it. I've already checked that it is 16bit format, that it is greyscale, it's the right filetype, I've clicked the option for IBM bit order, and I'm fairly certain it isn't interlaced. Not sure what I'm doing wrong.

[TrickyVein]

Are your quads named correctly?

 

http://geck.bethsoft.com/images/8/80/Overviewgrid.jpg

 

If each isn't 2mb than it's formatted incorrectly.

[PossiblyErich]

Okay, I completely missed that. Works now, although I really need to apply some blur to it and work with it, but that shouldn't be host to many technical issues. Though, before I really put time behind this, I should ask: I don't think I'll be editing more than 1 quad of playable area, but how many cells should I have to buffer so it doesn't look like the landscape ends abruptly in the distance?

[TrickyVein]

Not to call you out or anything, but I mention this explicitly, twice in the tutorial. :laugh:

 

You're asking how large a playable area you can get away with editing without having to generate terrain meshes for it? I guess a safe upper limit would be like a 5x5 area. You may as well not import anything if you're working across a space that small.

 

Generating terrain meshes for only 1 quad doesn't take a long time. You can just do it overnight and view your results in the morning. Whether it's convincing or not really depends on what it looks like, seriously - if you have a lot of flat ground, that's going to end, noticeably, no matter how expansive - if you have ridges or mountains, it becomes much easier to enclose an area and make it look like it's part of a larger world.

 

I always try and grab at least some feature or landmark on the edge of my heightmap so that there's some variation in the skyline.

 

My advice, if you really think that you can put in the time to work across all 32x32 cells in a quad, would be to import at least a 2x2 quad heightmap and have your playable area somewhere around the origin. When you go to generate terrain meshes, bear in mind that the dimension of your heightmap has to be rectilinear. You can't have a few errant cells popping out here and there, but it doesn't have to be perfectly square, either.

Edited August 7, 2013 by TrickyVein

[PossiblyErich]

Sorry about being dumb there. What I was getting after was more from observations of the main NV worldspace, there are at least a dozen cells of landscape beyond, and I wasn't sure how much of that is actually necessary. More of a newbie question to making a larger area, that I didn't really thought warranted a thread to itself. If I do use more than one quad, it'll likely be because it'll be a narrow width playable area, but rather tall in length.

 

I have a slightly more specific question after toying around with various terrain features of the last few days: how would I go about keeping certain features pronounced? It often seems certain interesting features, like a canyon or an iconic mountain, always seem to be quite dull after importing. The terrain around it is acceptable though, and when I use a gradient map with more colors in its range, it usually flips around, the terrain around the feature is much too extreme, but the feature is acceptable. I suppose I'm aiming to make somewhat of a caricature of an area. I have a feeling the answer is going to be manual editing either in the heightmap screen on the GECK, but I figure I'll ask anyways.

 

And thanks as always, this is a fantastic guide that's actually spurred me to learn a significant more about the GECK than I had known before, on top of you being really helpful.

[TrickyVein]

I'm glad you're finding it useful.

 

The terrain beyond the playable area which is the Mojave Wasteland isn't 'necessary.' It does looks good, though, and it makes the place feel larger than it really is. In this sense it is quite essential.

 

I think I know just what you mean about wanting to exaggerate some features in the landscape. The most effective way to do this is to modify the histogram of your image. In photoshop you can adjust levels to bring out lower values in your image, or higher values and modify the median, etc.

 

I've also used the magic wand tool to select a range of values and then adjusted the levels of these. If you adjust the brightness or contrast though you modify the endmembers which will break the transition from areas you've left unselected into areas that you've modified.

 

If you want to modify your heightmap in the GECK after importing while preserving the height of some areas, I think it's much easier to use the 'smooth' brush and flatten out areas that you want rather than trying to 'paint' onto the landscape. Know what I mean? It's easier to import a heightmap with a large range of values and flatten it out in select areas than it is to import terrain with a small range of values and try and modify areas using the paint tool.

 

It's a bit of a touch-and-go process until you find a heightmap that you're really happy with. It's not all technical, you see - there's a bit of creativity called for in deciding what it should really look like.

Edited August 12, 2013 by TrickyVein

[PossiblyErich]

I have a slight idea on what I wanted to do to solve this; this is a 10% - 40% gradient (give or take a few % at the minimum), and the canyon the Rio Grande (on the right) is about the height I want it. To actually make the place for the river, in photoshop I used a 3-4 point brush of 7-8% black to trace the riverbed, before the gaussian blur, and that came out nice. But the mountain range up near Los Alamos itself is way, way too high still. I aimed to lasso an area in the heightmap editor and then try to blanket lower that area by a low intensity, then lasso a slightly smaller area, lower it by a low intensity, rinse, wash, repeat, and then a blanket blur of that area. I'd do something much less convoluted in photoshop, but where the boundary of the lasso selection and the unselected section always has an abrupt end that I can never get to blur to be a nice transition. I'm aware the heightmap editor has the erosion function, but trying to toy around with it, every time I ran it it'd crash the GECK, so I assume it either doesn't work or I'm making it do things it doesn't want to.

 

Feel like a needy child at this point, but I'm not positive I'll figure this out on my own.

 

 

 

The blue area is the outermost lasso I figured would work.

 

The red areas I drew are the absolute boundary I intend to have for a playable area, and the magenta-ish color is where the borders are going to depend on how I actually manage to block it off. I think i'll be using this 2 quad area, because that same area was butting against the borders of a 1 quad area, where it'd look very abrupt. The topmost border of the image here is flush against the entire section I got from the USGS, and the rightmost border is close to being on the section.

 

 

[TrickyVein]

OK, just from looking at your heightmap I can tell you that it's going to be very noticeable where it ends or is cut off. There are no borders to the North, East or South.

 

You can preview your terrain in the GECK using the landscape editing tool, after importing. This is useful in case you want to make any adjustments before generating terrain meshes which takes an unseemly amount of time.

 

I don't know what else I can help you with, barring taking the image and modifying it myself. You may find it helpful to read a little about viewsheds to understand why it's a good idea to include or create natural borders around the edges of your landscape.

[PossiblyErich]

A'ight. I've got two worldspaces ready (one's a miniature one), and now I just need to (learn to) use the region editor. Thanks for everything!

[TrickyVein]

One more tip - if the GECK crashes during terrain mesh generation, it's probably because there are a few cells that have been modified outside of the quad. You can delete these from your .esp using fnvedit - and they're easy to spot because they're contained in an entirely new quad outside of the one you imported.