Exclude individual objects from lightsource?

[Andrew March]

Hi Guys, I have a scene where I want want of my objects to ignore light from one lightsource but instead be lit by a different lightsource.

Can anyone tell me how to acheive this?

Thanks in advance

[Matt]

This isn't currently possible. You would need to render two images and composite them together. Perhaps the second image could just be this one object that's different. If other objects partially block the object of interest then it becomes slightly more complex. You can render the object with the overlapping objects if you give them a Constant Shader with its colour set to 0 and its alpha set to 0. This will cause the overlapping objects to appear black in both the RGB image and in the Alpha image, allowing you to composite the object over the first image.

To save an alpha, press the 'A' key in the Render View to view the alpha image, then click on the Save button. Alphas can also be saved when you render an image sequence, using "Extra output images".

Matt

[Andrew March]

Wow Matt, really thought this would have been an existing feature, not being rude or anything but having to render out multiple images really increases production time and when you are a freelancer that can be the difference between making a deadline and finding yourself out of work.

Perhaps this could be added to the feature wish list please.

[Matt]

That's true. I can't help but think of Maxwell Render. That doesn't allow you to do *anything* that isn't physically correct. Definitely not the example I'm copying. Light linking is something we might add in future.

Render times for separate passes where most objects are matte objects are usually pretty low because the matte objects don't have to calculate any lighting or shading. The biggest hassle is manually setting up and managing the passes. We are developing Render Layer capabilities for Terragen 2.5 that will allow you to automate the setup of these different render passes.

Matt

[Andrew March]

Thanks Matt