Method for largescale (chunk-based?), seamless terrain

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  10 October 2012
Method for largescale (chunk-based?), seamless terrain

Hi forums,

I have done a fair amount of CG in the past, but all characters and architecture/ objects- never any terrain larger than a single model.

My goal is to make a terrain which is several square kilometers large. I am using Mudbox, Maya, Blender, and World Machine.

Now I would like to model in a large amount of detail to make normal and displacement/heightmaps from to project onto lower poly models of the same terrain. In order to do this, I need a very large number of subdivisions. Since I can't afford (processing wise) to subdivide the entire world like this at once, I guess I need to divide the whole world into smaller chunks.

I started out in maya, and made a plane with a grid on it, divided into 64 spaces, each grid square I gave its own uv map space, so I ended up with 64 uvs. Then I imported this plane grid into mudbox, where I will model each unit, and then import each unit's UVs into world machine, then world machine's outputs back to mudbox. So the terrain is made up of 64 smaller objects with their own individual uvs.

I have two major issues:

1) [what seems to be the much harder question] since mudbox can only sclupt one object per stroke, when I sculpt over the edges between object squares, they never quite line up again. What is the secret for having sculpted terrain chunk objects that have edges which line up? Do I need to rethink my method entirely to achieve this? Am I perhaps doing it backward? Do I model a fair level of detail, then divide the master terrain model into my 64 chunks from there? Even so, once I cross a chunk edge between two models with a sculpting tool, the seam is broken I would think...

2) Since I am working with 64 sets of uvs from the start, the process is incredibly cumbersome. Is there a way to make a master height map to first take into world machine, and then export WM's outputs, and then take all this into say Maya, and subdividie the whole model into the smaller chunks at that point, with the heightmap UV's being divided as well into their corresponding grid parts?

If all of this doesn't make sense, my question is basically what process do I use to create a massive seamless world (that may have smaller model parts or chunks) if I want to model in high details for displacement maps to project, with Mudbox, Maya, Blender, and World Machine at my disposal?
  10 October 2012
You can try the ANt landscape genrator.
  10 October 2012
The problem with using the ANT that comes with blender is that you are limited to making a world of size and resolution that your computer can handle in one single model, and furthmore since it generates the landscape for you, you can't begin from a sculpting.

What I am looking for is a method to make a landscape as large and detailed as I want, with sculpting at begining, heightmaps at the midpoint in world machine, and then more sculpting later to make the finished maps. It also seems that I need to have multiple models, and my question is is how do set up these multiple models or objects or landscape chunks so they seam well.

Here is a an image to illustrate my issues with my current method:

The edges don't line up, or else they need to clip and leave a visible seam. You can hide seams well in mountains, but not so well in plains.

the edges of each tile are also lower, because of the falloff function of mudbox sculpting, which tends to give a balloonish appearance to edges too; also, the edges don't stay vertically poised above where they start from, they also move horizontally based on sculpting angle, which is very undesireable.

Last edited by joeraynor : 10 October 2012 at 09:05 PM.
  10 October 2012
One option is to have your terrain in 1 piece, with the 64 uvs, and Mudbox will sculpt without seaming problems. Later on, you can divide the geometry and assign same displacement but diffent shader if you want.
The other thing I recommend you to try is something similar that I did for a large landscape. What I did was to build a 2 huge generic terrain maps, 1 with big details 1 with small details, that can be tiled, rotated, scaled or projected multiple times with a different blending mask so it looks different every time althoug is the same texture. They were placed camera wise, so that there were no visible repetitions near the camera's path, and it worked like a charm. If you need some areas that need mountains that are going to be identified, just sculpt those ones separatedly, even in a different geometry.

Hope this helps.
  10 October 2012
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