Triangles showing up on surface between two faces

[blowlamp]

You might need to check your scale settings somewhere as the table top comes into MoI measuring 4 x 3.14 x 0.002 inch and is also quite tiny in comparison to other objects in the file - it might also be far enough away from the origin to be causing a problem in Octane.

You should always model in real-world sizes.

I'll have a play here, but try getting the scene a bit more in proportion and see if it helps.


Martin.

[roeland]

Can you check if the normals are correct? You can do a quick check with the deep_channel_kernel: compare the output of the deep_channel_kernel in Geometric Normals and Shading normals mode. For flat surfaces like the table top this should render a solid color (normally the same color) in both modes.

This example shows a cube without vertex normals, a cube with vertex normals and a sphere. If you render a cube, both modes should render the same image as in the middle row. If you see a gradient as in the top row, then the vertex normals are incorrect, and you need to disable smooth shading in the material node to avoid artifacts in the image.

Is Moi3D exporting vertex normals?

--
Roeland

[Refracty]

I am sure this is about a tolerance problem.
Try to work with a smaller tolerance or scale the model by factor 10 and see if it works.

[blowlamp]

Roeland.

MoI 3d most certainly does export vertex normals.

Martin.

[roeland]

MoI 3d most certainly does export vertex normals.

Does the deep_channel_kernel / Shading normals give a solid color on the table top as expected? If so, can you attach the OBJ file of that table so we can check it here?

--
Roeland

[blowlamp]

I'm not experienced enough with Octane yet, so here's the .obj file for you to check - I made it in MoI3d from the STEP file the O/P uploaded here. The Weld vertices along edges option in MoI3d was not ticked for export.


Martin.

[GeoPappas]

Your model is huge. You need to reduce the size.

I opened it up in Blender and it says that it one of the pieces is 43,918 meters x 46,936 meters.

[FooZe]

Hi whersmy,

This definitely seems to be a scale problem or something blowlamp is doing differently.
With blowlamps obj if i use an import scale of decimeters the table becomes about the right scale.
To render the giant plane without artifacts then i had to increase the ray epsilon to about 0.005.
With these setting it will render fine:

(please excuse the poor material selection but it shows that these settings lead to correct rendering)

Cheers
Chris.

[blowlamp]

Look at the MoI scale setting in the third picture of the fifth post of this topic - perhaps that's the cause?
I think the default setting is 1 rather than 5. My .obj file was made with the default value.

Martin.

[whersmy]

Round 2. So far no luck, I have tried scaling down the scale factor in moi3d, exporting without welding vertices, importing in octane in meters, decimeters, adjusting the ray_epsilon and importing in decimeters. In Solidworks 2012 I modeled the table to 80mm x 100mm or 80cm/100cm, so that seems about right. These triangles show up every time there are two faces mated together, tangent. Which makes it really difficult to render glass for example.

Here is the deep_channel_kernel, the image for geometric normals and shading normals is the same, no difference.