OTOY Forums

I'm having a difficult time figuring out Projection Mapping in Octane v3 for Cinema 4D. I'm very familiar with the process using C4D's built-in renderers. I've done it many, many times. But Octane is throwing a wrench into my plans.

I have a Projection node with Perspective mode. And I have a Camera chosen that's used as the texture projector. And that's linked into an ImageTexture node which is piped into the Emission channel of an Octane Diffuse shader. (Emission is power 1, with Surface Brightness turned on).

The main problem is that the image projected onto the geometry is upside down and slightly stretched tall.

Secondly, if I pipe the ImageTexture into the Diffuse channel, the C4D viewport of the projected texture does not match what's in Octane's Live Viewer. So it's really hard lining up geometry to the image in the C4D viewport.

I'd post a scene, but the project is on an isolated machine without network access. And the machine I'm writing this on doesn't have an Nvidia card to run Octane. But I would appreciate any help (or sample file) figuring this out.

Distribution of emissions will not use uvmapping but a spherical projection. This is first mistake here. You need to connect your image it to texture slot not distribution. Second you'll need to use a transform node to rotate and scale for matching output. I think example scenes package have a sample for that.

There is another way rather than this. You can simply use camera mapping option in projection type from texture tags. And use it on a mesh which has some extra subdivision to avoid streching effect on uvmap.

You have to use Camera Mapping material projection and select the camera you want to project from, for example:
Make sure you have your film aspect set as per your source. Are you projecting a still or video? I'm personally having issues with projecting video with this method. I can project it fine but as soon as I hit play the projection starts to drift unlike when using Cinema's renderer.

Also, you don't have to use an Octane material to do this, you can always use a Cinema 4D material with your source in the colour channel. Personally I think doing it with Octane materials is massively counterintuative which I do hope gets a better solution in future. It would be another reason to not have to keep turning back to Arnold all the time.