mesh wishes for 1.X and beyond 1-7  8-23

 From: Michael Gibson 13 Aug 2007  (8 of 23)
 836.8 In reply to 836.7 Hi Jonah, in general using a coarse mesh can produce artifacts that are hard to avoid. But I'm not sure if I completely understand this particular issue from your description alone - can you please post an example that shows it off? - Michael

 From: jbshorty 13 Aug 2007  (9 of 23)
 836.9 In reply to 836.8 Hi Michael. Here is a simple case which produce at least 3 wayward vertices if you set the threshold angle to 34.41. I've also seen where the vertex would actually fold the face backward on itself (I don't remember how i created that particular situation). It's easily fixable by increasing the tesselation. but these stray verts are not so easy to catch unless you really look for them... jonah Attachments:

 From: Michael Gibson 13 Aug 2007  (10 of 23)
 836.10 In reply to 836.9 Hi Jonah, I see what you mean now. But those vertices are not exactly out of place - they are positioned on the surface and on the edge curve as expected. This is generally one of the kinds of artifacts that can happen when generating a very rough low poly mesh. I guess what you would prefer in this situation would be for another subdivision to happen on those longer n-gons so that they match up better with the outer boundary. I may be able to add some kind of analysis to try and tune up situations like this, I guess it would involve some kind of measurement to detect significantly non-planar n-gons and divide them some more. But the tricky part is to find some measurement that is not dependent on a hard-coded distance so that it works on objects of any scale. This artifact will happen only for certain angles, because you'll see it when the angle is right at some kind of boundary condition, like one piece of the surface is just barely within that angle next to another spot that is just outside of that angle, that leads to different levels of subdivision which causes this. You can also use some of the other controls to try and produce some additional subdivisions to solve it - for example Divide larger than 2 units, or Aspect ratio limit 20 in this case, but that will produce some additional details elsewhere as well. - Michael

 From: jbshorty 13 Aug 2007  (11 of 23)
 836.11 In reply to 836.10 yeah, it sort of relates to that discussion we had about "magnifying" the tesselation near extreme curvature changes... Are you planning to put in a control for max distance to surface, like Rhino's? I use that a lot to get nice results... jonah

 From: Michael Gibson 13 Aug 2007  (12 of 23)
 836.12 In reply to 836.11 > Are you planning to put in a control for max distance to surface, like Rhino's? I don't know... I've kind of been trying to not have too huge of a set of options but maybe I'll have to add this one in as well. - Michael

 From: Schbeurd 14 Aug 2007  (13 of 23)
 Always very interesting to see some topics about meshing... ;-) Can you please explain what UV nesting is ? It's not a familiar concept for me Thx Schbeurd

 From: Michael Gibson 14 Aug 2007  (14 of 23)
 836.14 In reply to 836.13 UV nesting would be a different way to handle the UV coordinates that are exported by MoI. Right now it uses just a simple system where every separate surface in a solid gets texture coordinates that span from 0,0 to 1,1 - that's across the entire texture image. So for example say you have a cube and you put a texture on it using the UV coordinates generated by MoI - each face of the cube would have an identical full image displayed on it. If you were to paint on a face to modify the texture map, you would see the same paint applied to all the other faces as well. UV nesting would change this so that each different face of the cube would be situated in its own smaller piece of UV space. With each face having its own separate chunk of mapping space it means that each one is independent so for example if you were to paint on one face to modify the texture map, it would only affect that one face and the other faces would remain unchanged. - Michael

 From: jbshorty 14 Aug 2007  (15 of 23)
 Here is an example of UV nesting, exported from Rhino as OBJ into Modo. You can see that all 26 faces in the polysurface are sharing the UV space with no overlapping. this makes it much easier to deal with texture mapping. And yes, i know this is a heavily tesselated mesh but that wasn't the point!!! :) jonah Attachments:

 From: Schbeurd 15 Aug 2007  (16 of 23)
 Thanks, It's perfectly clear now ! It's really a cool way to do the UV mapping for you ! ;-) Definitely something I'd like to see in MoI as soon as possible. So useful with texturing software that use projection painting, where you don't really need UV "continuity" (like Modo or ZBrush). You virtually don't need to edit your UV map by hand anymore with that option ! Maybe just scale or move some of the parts in the UV space... Is there any way you can control it in Rhino (for example to force some parts to "stay together" ?) Would such control be possible in MoI ? Can't wait for it ! ;-) EDITED: 15 Aug 2007 by SCHBEURD

 From: Michael Gibson 15 Aug 2007  (17 of 23)
 836.17 In reply to 836.16 > Would such control be possible in MoI ? I don't know - it is pretty hard to imagine how to control that without a pretty elaborate UI... Some programs can automatically calculate this kind of separation for you in their UV editors, for example I'm pretty sure someone has mentioned Blender can do it. But I'm not familiar enough with its UV editor to be able to give you the details. - Michael

 From: Schbeurd 15 Aug 2007  (18 of 23)
 836.18 In reply to 836.17 >> Some programs can automatically calculate this kind of separation for you in their UV editors, for example I'm pretty sure someone has mentioned Blender can do it. But I'm not familiar enough with its UV editor to be able to give you the details. Yes, you can usually do that in UV editors, by selecting the parts you want to UV and where the seams will be. I was more thinking at some sort of "pre-process" during the creation of UV map with UV nesting. It's some sort of "lazy" solution... ;-)

 From: jbshorty 15 Aug 2007  (19 of 23)

 From: Michael Gibson 15 Aug 2007  (20 of 23)
 836.20 In reply to 836.18 I think you should already have a natural seam in the UV coordinates for all the polygons that make up each face in a solid. Like for instance when you have a cylinder, UV coordinates are not shared along the seam of the cylinder, only 3D points are shared there. I wouldn't think you should have to manually specify seams. Anyway, it would definitely be more convenient to have this done automatically instead of needing to do an extra editing step. That's kind of one of the additional nice things of using a NURBS modeler, since every NURBS surface has its own UV space you get a UV mapping for everything automatically. - Michael