OTOY Forums

Hi all,

Can anyone give me a step through for bringing a photo background into the rendering. Im sure it cant be too hard because I see them everywhere but I cant seem to get it to match up with the rendering output.

I have an image in the background of my rhino perspective viewport so thats Ok and I can rotate, pan zoom etc to get the model into the corect postion.

I have then right clicked on the octane environment and loaded and environment from rhino??

I have also got my kernel set to path tracing and then set my alpha channel to enabled with a bool node type.

The image show in the octane render window but the scale is all out of proportion with the rhino window. is there a way to sync these. Surely I dont have to play with the octane render resolution to try to get them to look the same.

Can anyone give me some guidance as to how they achieve lining a model up with a background image in a realtively easy manner.

Cheers

Tim

Hi Tim,

I'm assuming you are using the Wallpaper command in Rhino? If so, that command will take the image you chose and stretch it to fit your viewport while keeping the aspect ratio, proportion intact. This is a great way to get the perspective and seating correct between your image and model. In Octane, You are working correctly, in choosing "alpha channel" and loading a background image, but the background image will be scaled depending on the size of the image. This is why its not working the way you expect. There are two easy ways to do what you are trying to do.

1) Keep the alpha channel on and then take your rendered image and background image into a photo editing program like Photoshop and composite the two. You can control everything this way and get the images to match very well in color and brightness.
2) Or . . . you can create a surface the same size as your image (same proportions) and assign your background image to a material and that material to the surface. Place the surface behind your model and you've got your image there. However, there's a catch to this -- the lighting in your scene will affect the surface your material is applied to with your background. Sometimes this is desirable, sometimes not. I do interior shots using this method often, when showing images outside of windows. You can play with gamma and power to help control the how the background image material looks. Sometimes opacity is even good to give the "overexposed" look to the outside image if shooting an interior shot.

Unless you absolutely MUST have an exact specific background in your images, you could also try using an HDRI image. Everything syncs up perfectly this way. I'm sure you are aware of that, but I'm not sure what you are trying to achieve, so I thought I'd mention it . . .