3ds max uv unwrapping and custom lod models? Workflow, huh?

[Benjamin Bigdipper]

Hi there. I'm fumbling with 3ds max and mesh.

How would I start setting up my different LOD models? I can't seem to find a way to make my high LOD model, unwrap the UV and then copy said model to reduce the polycount while keeping my unwrapped uv. Things like pro-optimizer don't really work for LOD models.

Do I really have to make 4 different models from scratch and unwrap their UVs? That tedious?

There's a lot of documentation about how to do things in 3ds max, but combining all these tricks to work out a good workflow in 3ds max seems beyond me.

Any suggestions?

[Maeve Balfour]

I don't work with 3ds, but my general workflow should translate anyway...

I generally create my full detail mesh intended for LOD1, and UV-map it etc as per normal.

For the lower LODs, I simple reduce the triangle counts in the original mesh, trying as much as possible to keep a recognisable shape - the further out you are, where each LOD kicks in, you will see less detail, so you can trim and merge triangles a fair bit. This is still tedious, but not as bad as redoing the mesh from total scratch each time (at least for me, anyway).

Regarding the UVs... What I do is use the existing UV layout of the main LOD1 mesh as a guide (it's easier if it already has a texture made for it for visibility), and just create the UVmap for each LOD mesh by overlaying it. If the lower LODs are reduced in triangle count, it isn't too much a hassle to UVmap them. You won't get a perfect fit over your texture UV, but near enough is often good enough for long distance viewing.

You'd be surprised at how much a good texture will "fill in" the missing geometry details for lower LODs at distance. Personally, I find it definitely worth the hassle of manually creating the LOD meshes and their UVs to retain complete control of how they deform over distance (instead of the totally random auto LODs generated by the uploader).

:matte-motes-smile:

[DanielRavenNest Noe]

Hi Benjamin,

What are you trying to make?

It depends what your model is how you do the LOD's.  For some objects, the auto-LOD within the upload window does a decent job of reducing the triangles, and it will map the UV coordinates reasonably well.  For other things, like the small plants I have been making, I use a "billboard" for the lowest LOD.  That is a couple of flat planes with a rendered alpha texture of the plant.  Since you need the number of material IDs the same at all LOD levels, that means having some hidden triangles at both the high and lowest LOD to hold the alpha texture and main plant texture respectively.  So in that case I have to do each level separately.  So there is no simple answer to your question.  Couple of things I can point out if you are fairly new to 3ds Max:

* You can "bake" the UV coordinates to your geometry by collapsing the "Editable Poly" and "Unwrap UVW" modifiers together in the Command Panel > Modify tab.  There are checkboxes both in the Editable Poly and Pro Optimizer modifiers to preserve UV's.  Those will help keep them in place when you make changes for each LOD.

* In the Edit UVWs window, you can use Tools menu > Render UVW Template from the high LOD model, and export the UV map as a texture.  In the other levels you can set that texture as a background in the Edit UVWs window, to help align your maps at the other levels.  You can also make your finished texture(s) for the highest level, and use them to align the UV mapping for the other levels.

 

[Marielle Caerndow]

Like you say, you can first make the hugh-poly modell, unwrap it  and afterwards reduce it's triangles. (Tip: the ProOptimize-modifer has a checkbox to preserve the UVs. Using it gives good results, however: the poly-reduction is generic, you can't exactly control it.)

You can also manually remove edge-loop from from the high-poly-modell. 

My experience is: when you start with the high-details mesh, it needs good unwrapping (no distortions, only minimum seams) - otherwise it becomes painful fumbling.

 The alternative is: start with the low detailed mesh and unwrap it. Afterwards create the high LODs by adding details to the mesh. Expecially if you use the traditional "box modelling" this way works well, because box-modelling starts with the low details, and then refines up to the high LOD. (other modelling techniques like Poly-by-Poly, Spline-, Patch and Nurbs-Modelling are better suited for the "high LOD first, then reduce workflow".)

[Nalates Urriah]

So far I have found this challenging and tedious. When laying out the high detail model I have to be considering the lower detail models. To make the UV Maps work, I am working with seams now. The seams have to be along a group of vertices that will remain through all the models. So, far I am finding I can do unwraps for each level and just a minor amount of tweaking. I've tried editing UV Map from the initial unwrap and decided that is too much trouble. I use Blender so I am still deciding if I'll have high to low details models within the same file on different layers or use separate files...

[Drongle McMahon]

"The seams have to be along a group of vertices that will remain through all the models."

I am just repeating this for emphasis. I can't begin to count the number of hours I have wasted by forgetting to make sure of this.

[Benjamin Bigdipper]

---

Marielle Caerndow wrote: You can also manually remove edge-loop from from the high-poly-modell. 

---

Hmm, how would I do that in 3ds max? Just selecting loops and clicking "remove" gets rid of the edges, but the face count stays the same.

In Blender you could just delete whole loops, and it would just merge the adjacent faces into one. I looked up "merge" in 3ds max, but that doesn't seem to exist.

Also, thanks to you and all the other people replying, every bit of information that is "sl and mesh" specific is really helpful. Tutorials about the various 3d tools are abundant on youtube, but there is only a handful of things about sl mesh, most of it from the early beta and therefore very outdated.

[Medhue Simoni]

What I tend to do, is create the highest count model, unwrap it, texture it, then make a physics box. I will then bring it all into SL and see how it all looks, and get a general sense of how low I can get the PE or land impact or whatever. I will also save the finished model in an OBJ file.

From there, all other changes are made by importing that OBJ file and editing it from there, with a fresh clean max file to create LODS with, or even just to make edits to the mesh. It is definitely kind of weird in 3ds Max. To reduce the model, you have to apply the Edit Poly modifier to remove edges without affecting the mapping, then you have to apply another Edit Mesh modifier on that to have that reflect in a vert change. I think attaching it to another mesh will work also. or saving it as an OBJ..

[Benjamin Bigdipper]

Hmm, thanks for that tip, but it seems to be working for me by just using an edit poly modifier with "preserve UV" checked.

And this seems to keep the texture pretty much the same, without messing with a new uv-layout again.

[Apple Pumpkins]

Pro-Optimize might be OK for LOD3 and 4 (just look at how sculpties load up). But I would recommend as someone said here to go into Edit Poly mode and manually reduce the poly's for LOD2 from LOD1.

Say you have a tube with 6 sides, and it bends with an interpolation of 3. We can make the tube have 3 sides and a bend of 1 interpolation - Just remove some edges first, vertices afterwards (as deleting vertices first will break the surrounding faces too). Make the tube 3 sides and make the bend very basic by hand removing two of the bends.  Just an example.

You will still retain the UV maps this way and it also just makes LOD2 better for those people who can't view LOD1 until they're close up. As I find Pro-Optimizer is the equivalent to taking a butchers knife to your mesh, usually.

Also like someone else mentioned here, UV map LOD1 and make the material for it first, apply it in Max and make it viewable in viewport. That way during poly reduction you can keep watch on your object and make sure the UV doesn't tear or bork along the way.

[Marielle Caerndow]

Marielle Caerndow wrote: You can also manually remove edge-loop from from the high-poly-modell.

- Hmm, how would I do that in 3ds max? Just selecting loops and clicking "remove" gets rid of the edges, but the face count stays the same.

Sorry, didn't see your question. When you remove a loop, hold the "Ctrl" ("Strg")- key pressed. This will remove the edges and all it's vertices.