Michael,
As I know when MOI export .obj it export some kind of vertex normals I don't know what is it. This vertex normals shows in Cinema 4D as Normal Tag.
When I remove this normal Tag it looks like this:


When I Import it to 3d coat for sculpting it also look like this:


I know that when I import obj from moi in 3Ds Max it also looks like this.

I want to work in 3D coat but it looks agly, people from 3D coat forum telling that cause is software that made obj I think they are right. And I think those vetex normals is cause.
What do you think?

Hi Andrei - the vertex normals are shading information that's included with the geometry. They are surface normals (surface perpendicular directions) included for each polygon vertex that tells the renderer how to shade the polygon as if it were a smooth surface instead of actually a flat facet.

It's important to have vertex normals go through into your rendering program in order to have the shaded rendered result look the same as the original NURBS surface data. That's because the vertex normals that MoI exports come from the original NURBS surfaces, so they're very accurate and make the polygons get shaded to look the same as the original NURBS model.

If you throw out those vertex normals, then the renderer will calculate new ones for you (you have to have some kind of vertex normals for rendering or else everything would be all flat faceted shaded instead of any smooth shading at all), and the ones that it calculates will come from averaging the polygon face normals that are adjacent to the vertex and it's easy with CAD generated data for there to be large polygons next to small ones and that does not work very well with that sort of averaging process.

So you do not want to throw out the normals like you did in Cinema4D.


For 3D Coat I guess it will depend on which particular process you are using in 3D Coat, if you for example bring in a model into the voxel module there it's not polygon data anymore and new polygons will get created later on. If you are using some other module then maybe there's an option for whether to bring in vertex normals or not.

If you don't get vertex normals to come through then pretty often you will see shading artifacts.



> I know that when I import obj from moi in 3Ds Max it also looks like this.

The Max OBJ importer has a lot of problems especially in slightly older versions of Max, it's best to instead use FBX format for transferring into 3DS Max.

- Michael

Hi Andrei, also if you know that you're going to be taking your model somewhere that does not support vertex normals to get accurate shading it can help somewhat to try and make more regularly sized diced up polygons output using "Divide larger than" rather than having some big polygons right next to small tightly curved areas with lots of little polygons.

That can generally help to avoid shading artifacts.

Polygon shading artifacts are a regular part of many kinds of rendering situations, the whole appearance of a polygon mesh is kind of faked to be smooth when it's actually made up flat facet pieces. There are various situations where the flat facet nature of the actual polygon geometry can end up being revealed.

- Michael

As i can see there is no any option when importing for voxeliszing or surface sculpting. But when import for retopology, UVs or paint thereis option Lock Normals. That do not recalculate normals but use them directly from object. And it works good.

Michael is it any way to convert this vertex normal to normal map? And what is main difference between them?

Hi Andrei,

> Michael is it any way to convert this vertex normal to normal map?

Usually there is not really a direct conversion from these, a normal map is generated through a type of rendering-like process that bakes geometry information into a texture map.


> And what is main difference between them?

They are kind of generally similar in what the final effect is, that they control how shading happens with light sources. The main difference is vertex normals are attached directly to the geometry (with one vertex normal per polygon vertex), while normal maps have the normals in the form of a texture map instead. It's a texture map that contains x,y,z information in it basically instead of only color information.

Normal maps are meant to give higher detailed looking shading results to lower resolution geometry.

- Michael

Thanx)
Michael have this problem, that practically do not allow me to Paint, Retopo and UV in 3D coat..((
http://3d-coat.com/forum/index.php?showtopic=14850

May be you well suggest me something. Cause it's looks very bed for me.

Looks like I solve this problem.
I thought this way - I made High Poly model in MOI then export it with N-gons. High poly model will not be used fro animation or subdividing so it can have N-gons.
Model with N-gons looks more friendly for UV unwrap. One potential problem that can be it is backing normal map on low poly. Low polly I'll made in MOI or manually in retopo without N-gons. I have some test it looks like everything backed good with N-gons.
Tell me what do you think about it.

Hi Andrei,

> Michael have this problem, that practically do not allow me to Paint, Retopo and UV in 3D coat..((
> http://3d-coat.com/forum/index.php?showtopic=14850

Sorry, I don't really know what's going on there, from what is described in that thread it seems to be a problem specific to 3D Coat that it's sensitive to certain kinds of geometry.

Did this happen when you exported using N-gons? If so then try exporting using "Quads & Triangles" instead of n-gons, it's not all that unusual for programs to have some difficulty processing complex n-gons and make bad triangulations when it has to convert them.

- Michael

No with N-gons it works very well. But that problem was when I exported with "Quads & Triangles". Its look like when a lot of small triangles close to overlapping cause this problem.

Hi Andrei, try using "Divide larger than" to break your model up into more regular smaller pieces, that has a tendency to reduce long skinny triangles that go across a larger area of the model.

- Michael

But also a triangle like the one shown here (in your very first post there) is not really particularly skinny at all:




- Michael

I tried use - divide larger than, to make very high poly model, holes become very small but still exists.

Hi Andrei, it seems that 3D Coat is just sensitive to triangles I suppose, maybe it's become more specialized to only work with sub-d quad topology or something like that.

The triangle that I circled in the above image is not particularly skinny, if it can't handle triangles like that it probably isn't going to work directly with MoI's output and I guess you'd need to do some retopology work in that case.

I'm not entirely sure if I understand the thread 100% - did the first problem image that you posted just suddenly stop happening or something like that?

- Michael

For the teeny-tiny slivery black ones, possibly that's just a problem within the 3D Coat real time display. What happens if you export those meshes out to one of your other rendering programs, does the actual render look ok? If so then that's just a display glitch that you should ignore in 3D coat and just go about doing your work.

- Michael

No I still had those problem, I think Iexport model with another cage and thought that problem solved.
The problem is that it do not draw on that holes when paint)
But I use now ngones looks like working good.

After 2 days of experimenting I found best way for worfkflow MOI and 3D coat.
Export from MOI High Poly with Ngons. It's not necessary have to be very High poly just enough polygons to trunsmit smooth geometry, 12 is a good number.
After that imoprt it to 3D coat, and make retopology, 3D coat has good tools for this. Or you can export from MOI Low Poly (has some issues).

Hay Michael, Just record this video to show workflow.

Interesting..
in middle of video you merge first re-topo object with original one from Moi? Is it right?Why?
If you can, tell more about this process,first time for me to see 3D Coat in action..i'm curious :)

M

This process is for making low poly model (for games or animation).
Yes after retopo, I merged it with model from MOI. It necessary for creating normal map. This normal map repeats all details from high poly model and apply it to low poly model to have practically all details from highpoly.
So another words you have detailed low-poly model.

Many thanks,Andrei !