OTOY Forums

Hi again.

I have a question. In the attached image which is a screen grab of my Octane session, you can see a simple setup where a pure white diffuse surface is applied to a mesh. The mesh is lit by an hdr image. The question I have is, since the diffuse mesh color is pure white and the bright area in the hdr image is grey cement, why is the mesh darker than the cement, especially since the flat surface of the mesh is in basically the same orientation to the sun as the cement? Do not meshes respond accurately to the hdr environment?

In troubleshooting this problem I noticed a couple of other things that do not make sense in Octane:
1. Why are there two Power settings in the Texture Environment settings?
2. What is the purpose of a meshes default material? It does not seem to have any effect at all.

Thanks as always!

The disc seams to have two materials where the second is not visible in the render.

Two powervales where the first is for the image itself and the second is the lightpower of the environment.
Changing the first to zero will give you the materialcolor.

face via andriod

The disc seams to have two materials where the second is not visible in the render.

That's just it...The "Default" material always comes with a mesh (corresponding to the pin on the far left) but it never seems to do anything. I can move the sliders to any wacky settings and nothing ever happens.

Two powervales where the first is for the image itself and the second is the lightpower of the environment.
Changing the first to zero will give you the materialcolor.

Do you mean then that the first Power value is essentially the brightness of the image? Rather like a brightness adjustment in Photoshop? And then the second setting is how much that first setting affects the environment?

Correct.
The first can used as a mix between the material and the texture.
The second one is the intensity of the first one.
To understand it better, the power, gamma, scale and invert is in a seperated secton. It only affect this section.
Whereby the image, power and rotate affect the environment.

face

Hi,

Is it possible that the HDR environment includes a skydome but not the sun?

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Roeland

Thanks, face.

Roeland: No. The Sun, sky and clouds are there when I rotate the scene around to search for them. There ARE fairly small black holes at the top and bottom of the hdr, so it is not a complete sphere when projected. But the Sun does not get clipped by the top hole.

Roeland > Actually, maybe you are talking about something I am not familiar with. Are you saying that even though an hdri can have a sky, clouds, etc, that it can also have a skydome included that is invisible in the image but embedded in the file? Or would the sky have to be gone, and REPLACED by a sky dome?

No, it will have the sky, sun, and all other illumination from the environment included. I am asking because the disc not only has a low brightness, but also seems quite blue. It's like it is in the shadow of something.

Can you attach the environment map?

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Roeland

Hm, good point. I never would have thought of that. But I don't THINK that's the case since I can pick up a reflection of the sun in the disk surface when it is reflective. And in looking at the image, there are not any long shadows...it's in the middle of the day and the picture was taken out in the middle of the street away from any cover.
At any rate, here is my ocs file and the hdr in a zip. I had to res-down the hdri to get it to upload.

Beyond that...What IS that default color area for, in a mesh's settings? It just seems to sit there and do nothing.

The environment map shows the sun, but its brightness is clipped, so illumination from the HDR is missing the direct light from the sun. You can see this if you decrease the brightness of the environment map, the sun should be much brighter than the sky around it. You can't fix this directly inside Octane yet. One workaround is to simulate the sun by create an emitter some distance away.

And the material pins are created from the materials present in the exported OBJ and MTL files. Perhaps the exporter is creating an extra material pin called "default material" for objects without a material assigned.

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Roeland