Triangles in render, not in SketchUp model

Coen Naninck · Post by **Coen Naninck** » Fri Jun 03, 2011 7:21 pm

This is my first post in these forums, so hello to all of you.

I've discovered Indigo about two weeks ago and have been hooked on it ever since. I'm currently trying out the trial. I think it has the best output I have ever seen, even surpassing V-Ray, whom I've long considered to be the rendering king.

SketchUp I have been using since July 2004, at which time it was at version 4.

About my issue; Attached are two images of a model I created a few years ago of the XBOX (1st version). The first image shows an NPR exported from SketchUp:

: SketchUp NPR output.

The second image is a render made with Indigo:

: Indigo render output.

Notice the triangles on the render? I would like to know what cause these.

Note that on my 2nd attempt I removed the bump mapping from the material, then I restarted the render and the issue was gone. I guess I would like to know if bump mapping is known to cause triangulation in meshes.

My system and software details are in my signature.

snorky · Post by **snorky** » Fri Jun 03, 2011 10:11 pm

I'm sorry but I don't see triangles...

Post by **fused** » Sat Jun 04, 2011 3:51 am

Hi Coen!

The problem you are seeing is due to long or stretched triangles in the mesh. Bump mapping does not work very well with them. Currently there is no fix for that other than to change the mesh to not have any stretched triangles.

Cheers and welcome!

Coen Naninck · Post by **Coen Naninck** » Sat Jun 04, 2011 4:29 am

Hi Fused, nice to meet you!

I offset the outer Edges as well where the problem occurs, which is a trick you can do in SketchUp to remove shade artifacts. I have yet to try if this will work with bump mapping, because I forgot that I changed both the mesh and removed the bump mapping from the material.

Quick side question: Are posts kept in moderation for all members, or do you have to have a certain amount of posts before they no longer need to be moderated?

Post by **fused** » Sat Jun 04, 2011 4:51 am

Coen Naninck wrote:Hi Fused, nice to meet you!

I offset the outer Edges as well where the problem occurs, which is a trick you can do in SketchUp to remove shade artifacts. I have yet to try if this will work with bump mapping, because I forgot that I changed both the mesh and removed the bump mapping from the material.

Quick side question: Are posts kept in moderation for all members, or do you have to have a certain amount of posts before they no longer need to be moderated?

You need to have two approved posts to be able to post without awaiting moderation.
Which you have now.

Coen Naninck · Post by **Coen Naninck** » Sat Jun 04, 2011 4:52 am

Ah cool, so now I can spam the heck out of this forum.

j/k

Pibuz · Post by **Pibuz** » Mon Jun 06, 2011 9:54 am

Hi Coen!
Nice to see you here! I'm a long SU and Indigo user, and I'm very happy you've joined us!

...odd that you do this only now, since it's years I post SU+Indigo renders on the sketchucation forums

BTW, I can't understand your issue: never occured to me!
Tell us if you get to solve it!

Coen Naninck · Post by **Coen Naninck** » Mon Jun 06, 2011 10:38 am

Hi Pibuz,

Thank you for the welcome! I'm glad to be here as well.

As for the issue, I just tried it again turning bump mapping on without modifying the surface of the mesh and now the triangulation is gone. Weird.

Pibuz · Post by **Pibuz** » Mon Jun 06, 2011 7:15 pm

Maybe the value was too strong?
..bump is a very sensitive parameter in SkIndigo (don't know about other exporters..)

Coen Naninck · Post by **Coen Naninck** » Mon Jun 06, 2011 7:27 pm

It was just for trying out anyway. I am getting familiar with all of I's settings.

Frutiger · Post by **Frutiger** » Wed Jun 15, 2011 11:24 am

fused wrote: The problem you are seeing is due to long or stretched triangles in the mesh. Bump mapping does not work very well with them. Currently there is no fix for that other than to change the mesh to not have any stretched triangles.

TIL. Good one to know!

bioman666 · Post by **bioman666** » Sun Nov 04, 2012 8:05 am

Hi to all !

I'm having the exact same issue, and i'm having a hard time getting rid of all the stretched triangles...

I'm using a model from CATIA, so i get a lot of details, and Indigo does not seem to enjoy it when I use a bumped material (rippled plastic, from Indigo library).

Anyone has a workaround ? I've trying cleanup3 (SU plugin), in vain...

CTZn · Post by **CTZn** » Sun Nov 04, 2012 9:19 am

Very thin triangles and bump mapping do no cope well together indeed.

Your best take would be to add curves that would drive the tesselation process in order to avoid the generation of too thin triangles.

Your Indigo is up to date, is it ?

Headroom · Post by **Headroom** » Sun Nov 04, 2012 12:50 pm

When exporting from any CAD program I'd suggest to use .stl format.
I have done this often with Solid Works (at work) and Alibre Design ( at home).

It triangulates better than other formats. In general you can expect to have problems with CAD exports with programs like Sketchup that won't give you full control over geometry on a polygon level ( at least out of the box ).

bioman666 · Post by **bioman666** » Sun Nov 04, 2012 1:26 pm

Your Indigo is up to date, is it ?

Almost. 3.2.13, but I haven't read anything on this bump issue on changelogs to date.

When exporting from any CAD program I'd suggest to use .stl format.

Yeah, I did so. Tried import with "Jim" plugin, or using meshlab (stl to dxf) then SU pro. No difference there...