A few questions about subdivision and uv mapping in blender...

[Dardissounet]

hi guys, I have figured out what my problems are with importing into second life but I still do not know how to fix them. I have a few questions to ask if y'all don't mind :)

1. How does subdivision affect the UV map, and if it does, how do I subdivide in a way that won't screw the uv map up and stop the baker from saying that I don't have a sculpty selected and thus prevent the baker from baking the sculpt map?

2. If I were to extrude or, how would I compensate, or could I even compensate in the first place?

3. What kind of workflow/methods do people use to make very intricate prims while retaining a uniform uv map and keeping it as a sculpted prim?

4. Does proportional editing prevent these calamities from happening?

I'm not bad at modelling in blender, but these conventions/constraints of sculpted prims confuse the hell outta me, let alone how to go about working around them! Any help in layman's terms would be duly and greatly appreciated :)

[Drongle McMahon]

If you are familiar with Blender, why don't you make proper meshes instead of sculpties? You can't add or remove vertices from sculpties at all (well, you can if you are very clever, but...). You can't do extrusions or subdivisions. You can't have any shading other than smooth.To get effects where you might use these in normal mesh you usually have to use various ways of collapsing sets of vertices to the same positions, but leaving them unmerged. This leaves degenerate triangles with no area which get culled from the rendering queue. All this takes a lot of learning and the results are not very satisfactory, especially for texturing. You have to contort the texture as you cannot edit the fixed UV map.

[ROMSEY Homewood]

Hi Dardissounet

In reply to Q.3 you can make intricate sculpted prims quite easily. Just remember that your UV map size should equal 1024, (Domino Marama's scripts) anything above this the LL viewer ignores so your lovely curvy shape will not be displayed but more of a blockier version...So as you may know you can create a cylinder in Blender (8 x 8 plus subdivision level 2+use subsurf+clean LODs) and it will rez pretty much as you see it, But you can also create very intricate scuplted prims by 8 x 128 (Subdiv 0 no subsurf) and even 4 x 256 (Subdiv 0 no subsurf) which then you can break into bits by zeroing 2 adjacent vertices. You can actually have a 32 piece sculpted prim which rezzes perfectly (remember 1024 pixels!). If u use the latter 4 x 256 (cylinder) dont forget to go into top view and rotate it 45 degrees and then (in object mode) press ctrl + A and select "scale and rotation to object" this will stop your sculpty map being "askew" by 45 degrees when rezzed which makes scaling a nightmare.

 

Edit: Sizes that work best : 16 x 32, 8 x 128, 4 x 256 pixels per UV map. (no subdiv And no subsurf).

 

Hope everyone finds this helpful. :cathappy:

[Nalates Urriah]

Drongle has the best answer. You need to change over to mesh and give up on sculpties. The limits on sculpties are complex. See Domino Marama's site: Primstar

Sculpties were intended for organic shapes. We learned how to build hard-edged shapes but it is a tricky and I think tedious process. I can model man-made looking things much easier and faster as mesh. I can also use more if the tools available in Blender.

Sculpties have their use. But, I have no use for them.

[Nacy Nightfire]

"Sculpties have their use. But, I have no use for them."

I second that . 

[Masami Kuramoto]

Why people still bother making sculpties is beyond me. And frankly, considering the lag they cause, LL should disable new sculpt map assignments altogether.

[Fizz Savira]

On the plus side for sculpties is that you don't have to produce multiple versions at different LOD's, you just have to take LOD into consideration during your design.

And if you'd like help making sculpties, I would highly recommend the JASS/primstar software (there is a free version you can find inworld on the JASS sim) and a *very* helpful user group.

 

[Nacy Nightfire]

If one were to totally depend on the mesh uploader for lod creation rather then making them by hand, one would STILL get a better result then with sculpties in my humble opinion.

[Masami Kuramoto]

---

Fizz Savira wrote:

On the plus side for sculpties is that you don't have to produce multiple versions at different LOD's, you just have to take LOD into consideration during your design.

---

Sculptie LODs are the same thing as multiresolution meshes in Blender. You can enjoy all the benefits of mesh (free-form topology and UV layout, 16-bit coordinates, accurate collision detection, improved DRM etc.) without substantial workflow changes.

Sculpties just don't make sense any more.

[Fizz Savira]

Interesting. I had stopped using Multires after some update long ago to JASS which switched over to Subsurface.

One of the things I dread in mesh work is making the other LOD's...

I guess I'll have to take a look again - any advice to share while using it? Does it handle UV maps well?

Thanks!

 

[Masami Kuramoto]

The problem with Subsurface is that you can't edit the high LOD until you apply the modifier. And once you apply it, you lose the low LOD. With Multires all the lower LODs remain accessible, and while you sculpt one of them, all the others change accordingly. Since Multires has been implemented as a modifier in Blender 2.50 and later, you can even change the topology of the base mesh without losing all the work done at high LODs. And of course the higher LODs will automatically share the UV layout of the base mesh, so you need to unwrap only once, bake only once etc.

[Drongle McMahon]

However, as far as I can see, now that it's a modifier, you can't use edit-mode tools on the higher resolution vertices (until you apply and lose the lower res). In fact you can'teven see them in edit mode. So it's the sculpt mode tools only. No numerical vertex placement etc. For me this greatly reduces its usefulness, although that's probably because I don't know/use sculpt mode. Is that right, or am I missing something?

[Masami Kuramoto]

That's right, Edit mode can only see the vertices of the base mesh. However, you can import vertex positions from another mesh using the Reshape function.