Easiest way to create LOD Models?

[Gian-Reto]

I am pondering this question since some time, but with my first game ready model nearing completion, the answer to this question is becoming more important to me:

What is the easiest way to reduce polygons and texture resolution on an existing 3D Coat Model? Do I really have to create a new retopo (I guess I can copy an existing Retopo group to a new UV-Set and start from there)? Is there a way to bake the existing texture layers to a new UV Layout, or keep the UV Layout with a reduced polycount in a way that the texture layers will fit with minimal changes?

I've seen a video about applying a texture to a different topology somwhere in another thread, but I can't seem to find it anymore... anyone having the link?

Thanks in advance for the help

Gian-Reto

[Eric Cosky]

I'm no expert at 3dc but since nobody else responded, I'll try.. but take all this with a big rock of salt because I'll probably be a bit off somewhere.

I think what might work best for LOD is to export your mesh (don't bother with texture/uvs) to another program that has poly reduction features (which is probably most of them). I use Softimage, and I would use the Poly Reduce command to let me dial down the poly count while keeping the general form. Then export that model to OBJ. In 3DC, with your high-res model already painted and loaded in the Paint room, go to the retopo room and import the OBJ as a reference mesh. Unwrap the new topology (== create a new, different uv set), taking the time to manually place seams if you want, then use the "Merge with NM (per pixel)" command to bake the texture found in the object in the paint room to the new UV set. Obviously you'll want a suitably smaller texture for this lower res uv set so the lower LOD model will provide better performance (smaller textures = better perf = why you do low lod in the first place).

Check my thread history for a few links on related topics, this is something I've had some trouble figuring out myself and people were kind enough to help out with.

[Gian-Reto]

Thanks for the answer, I'll definitely check your thread history...

Okay.... I might try the poly reduction tools in Blender, I faintly remember there being tools to do just that. Just to see if that works.

My bigger issue is though: If I have my reduced mesh, all nicely unwrapped with seams placed in 3D Coat.... how do I bake the Texture layers of a different object to that new UV Set? Is there a command for just that in 3D Coat?

[Eric Cosky]

Just have the original high res painted mesh visible in the paint room and use Merge with NM (per pixel) with your reduced mesh in the retopo room. This will cause the object in the retopo room to be copied into the paint room as an object, baking the texture sampled from the objects currently visible in the paint room in the process. The docs do a poor job of explaining this, but that seems to be how it works. I am pretty sure there other ways to bake textures in 3DC but I've never looked into it much, it was hard enough to figure out how to do just this much.. It's really hard to tell from the docs what is and isn't possible with respect to baking textures, it seems to be mentioned only in passing as if people only needed to be reminded of something they already knew how to do as opposed to it being a significant feature that warrants a detailed explanation of what is possible and what specifically to do to use it.

[Gian-Reto]

hmmm.... sound almost too easy to be true. Does this really work with changed topology? Easy enough to try, I guess, but still.... 3D Coat does all the magic of figuring out what part of the original painted model goes where in the new UV Set, without even "bragging about it" with some special function/tool/whatever?

But I'll check it out as soon as I have a reduced mesh.

[Gian-Reto]

Well, that didn't work out.

I had a painted object with a mesh created by autopo. I created an additional mesh with its own UV-Set and Retopo-group. I unwrapped the UVs, and tried to merge it into the paint room (both Pixel base). I got an enlarged dialog, asking me now about the size of two UV texture (I assume the original one to take the Texture from, and the target, but thats not written anywhere, its just my guess)...

After the merge though, I get 2 Objects in the Paint room, but no new Texture channels. Also, if I enable the new Object, I only see part of the Objects, parts are invisible. And also, while there clearly is a normal map and baked occlusion on the object, the diffuse texture has not been copied over in any way.

Is the problem here, that I didn't even tried to match the UV layout of the original? Is the problem, that the original object was created with autopo instead of manually remeshing it?

[Carlosan]

Hi

- Highres painted mesh visible in the paint room.

Is an object sculpted at Voxel Room using Surface mode.

Done

- Go to the retopo room and import the OBJ as a reference mesh

Done

- Unwrap the new topology.

Not done, i need to use the UV set done in another app.

- use Merge with NM (per pixel) with your reduced mesh in the retopo room

Done

- At Paint Room file export model. Set the pop up window

Done

AND ITS WORKS PERFECTLY !!

TY SO MUCH ERIC !!

[AbnRanger]

Another approach would be:

1) Reduce the poly count by deleting edge loops in the Retopo Room (use the DELETE EDGES tool and select EDGE LOOPS at the top of the UI). Can be done very quickly.

On a side note, I have requested a DOT LOOP/RING feature, for a long time now. What that does in 3ds Max is select every other Edge loop or ring, and that way a model can be reduced in half in just a few clicks. If you want to see that in 3D Coat, help me bug Andrew about it

2) Modify UV's if needed (in Retopo Room)

3) Export the low-poly version, from within the Retopo room (lower portion of the Tool Panel or Retopo Menu).

4) With your High Poly version loaded in the Paint Room with all the texture maps you created, use the TEXTURE BAKING TOOL to bake those textures onto your low poly version.