Projection Man / Camera Mapping in Octane Tweet

[animas3D]

Hello,

I have been using Octane for a fair amount of time and I wanted to do a camera mapping, Projection Man project.

Previously, with C4D's native renderer, the image that was used to be projected from the camera was stored in the Luminance channel of the material. This made it not be affected by the lights in the scene, since it was, naturally, pre-lit when the image was photographed. Nor did it emit light.

However, I don't seem to be able to find a Luminance channel in an Octane shader. I see that there is a way to project a material from the camera, but it seems to be affected by the lights/environment in the scene (unless I am doing something wrong).

Therefore, I have a few questions:

1. What is the proper way to do projection mapping inside of Octane so that the projected materials are unaffected by the lights or the environment in the scene?

2. Will there be updates to this process in Octane 4 when the plugin is available (by the way, when is the plugin going to be available)? Will there be a Luminance channel like in C4D?

3. How are others handling doing projection mapping in Octane? Are there any example scenes or tutorials out there that you can point to?

Thank you!

Joe.

[aoktar]

See this
viewtopic.php?f=30&t=66632#p336171

[animas3D]

Thank you for pointing out the example scenes.

It does seem, however, that the projection is still being lit by a white environment. However, I need the projected texture to look precisely like the projected photograph. That is why the Luminance channel works so well in this case. Would I be right in assuming that this cannot be done in version 3? Can the texture be self illuminated without having to use lights? This is important for compositing.

Importantly: Will there be an option in version 4 to have a self illuminated texture without having to light it in Version 4?

Thanks again.

Joe.

[aoktar]

It's exactly possible. Disable cast illumination in emission and use black diffuse.

[mesut]

It's exactly possible. Disable cast illumination in emission and use black diffuse.

how does one "disable cast illumination", is there a checkbox, i don't see any? (rc4)

[bepeg4d]

Hi mesut,
we were used to disable the Cast illumination parameter in the past, but from 3.07 has been splitted in Visible on Diffuse, and Visible on Specular parameters.
ciao Beppe

[mesut]

Hi mesut,
we were used to disable the Cast illumination parameter in the past, but from 3.07 has been splitted in Visible on Diffuse, and Visible on Specular parameters.
ciao Beppe

ok, thx.

[animas3D]

It's exactly possible. Disable cast illumination in emission and use black diffuse.

Hi mesut,
we were used to disable the Cast illumination parameter in the past, but from 3.07 has been splitted in Visible on Diffuse, and Visible on Specular parameters.
ciao Beppe

Thank you very much! This is very helpful. However I just want to clarify a couple things and have a couple of questions regarding setting up the shader properly.

1. In the emission channel of the shader, do I set it to BlackBody emission or Texture emission? So far I am testing using BlackBody.

2. Ahmet's post said "Disable cast illumination in emission" but that option is not there. However bepeg4d said that in 3.07 the two check boxes "Visible on Diffuse" and "Visible on Specular" are the equivalent. So basically what you are saying is that I need to uncheck those. Correct? (I also unchecked "Transparent Emission" and "Cast Shadows" since they don't seem needed).

3. the texture was too bright so I lowered it the Power to 1. Does that mean it matches the original? It looks right.

4. The "Surface Brightness" checkbox should be on...

3. Normalize should be on...

4. Finally, I noticed that the image in the shader when it was applied to an object looked too blue so I slide the temperature to the left. This is okay I guess. I can slide the temperature to what I think looks good so that it matches the original approximately. However, is there a way or a number to have it so that it does not contribute any color temperature to the texture?

Thanks again for your help!

Joe.

[bepeg4d]

Hi,
use the Texture emitter node, instead of the blackbody node, that is used to mimic real lights.
If you disable the Visible on diffuse option. the emitter does not contribute anymore to lighting the scene, so roughly the other options are not important.
ciao Beppe

[animas3D]

Hi,
use the Texture emitter node, instead of the blackbody node, that is used to mimic real lights.
If you disable the Visible on diffuse option. the emitter does not contribute anymore to lighting the scene, so roughly the other options are not important.
ciao Beppe

Thank you Beppe, you have been extremely helpful. I have just some clarifications and one more question.

As far as the power of the light is concerned, I suppose setting it to 1 makes it the same brightness as the original? However, what about the temperature? Is it possible to bypass the temperature contribution to the image? This is not that important since I suppose I could slide it around until I think it looks good. However it would be nice to know whether there is a way to bypass it.

Finally, one more question. I would like other objects to cast shadows onto the geometry that uses the projected texture. What is the best way to do this? I haven't done much shadow catching in Octane. Is it done with a shadow catcher? In C4D native renderer, there was a way, I believe, to use a compositing tag to make a material not affected by lights to nevertheless receive shadows.

Thanks,

joe.