(Resolved) [HOU-4371] Gobo Light projection to simulate film projector

[RichardBlank]

Im trying to create the look of a film projector in solaris. So far I have tried a rectangle light with a light filter, but as soon as I turn the direction of the light down the image get super blurry. Is it possible to do this with a point light or is there another solution?

[Gosho.Genchev]

Hey RichardBlank ,

Assuming I'm understanding the goal correctly, you may try increasing the Directional option (under the V-Ray tab of the Light settings) to some value that is very close to 1.0. This should force the illumination from the light to come as parallel rays thus avoiding 'blurring' of the texture used as a ligth blocker. Usually people would also drop a Softbox texture for additional control over the illumination produced by the Rectangle lights, e.g. something along those lines (I've also attached the scene):



I am curious about the fact that the projection you're getting gets blurry as your change the light orientation - if possible, I'd really appreciate a HIP file to find out why that is happening.

Best regards!

[RichardBlank]

No I get the same result as you but I would like the projection to be emitted from a smaller point, like a cone as you get with a film projector. Im also using fog to simulate the rays.

[Gosho.Genchev]

Hey RichardBlank ,

That would be a 'Spot' light then, correct? I've attached a screenshot from 'vanilla' Houdini below - it appears we haven't added light filters support for the spot lights in Solaris - I'll log it as a feature request.

It's doable in Solaris as well - the "Point" light type has to be selected, and "Spotlight" enabled in the Shaping options below. I'll keep you updated on the light filter support with this workflow.



Best regards!

[RichardBlank]

Where do I plug in the texture in solaris?

[Gosho.Genchev]

Hey RichardBlank ,

That is my point - it should work as a light filter but currently it does not. I'll check with our devs what can be done about this, and get back to you.

Best regards!

[RichardBlank]

Ok I misunderstood

[Gosho.Genchev]

Hey RichardBlank ,

There is now support for light filters when using the Spotlight option under the "Shaping" tab of the lights in Solaris. I've attached a simple example scene below.

HOU-4371.lgtFilter_emissionColorSupport.hip.zip

Hope that helps!

[RichardBlank]

Ok great! Did you use the latest nightly?