I'm working on an animated film and the director wants a similar effect to the shot about halfway through this clip from Up: https://www.youtube.com/watch?v=H-BRCMCg0N4
The balloons fly past a window and fill the room with color. I'm using a colored gobo and a spotlight to simulate this effect, but it's adding more light to the scene rather than blocking the "sun" (another spotlight) with the colorful balloons like in the clip above.
I've tried increasing the density of the gobo, but then I lose the color along with the light intensity. I've tried keying the intensity of my keylight (another spotlight) but I can't get it exact. Is there an easier way to go about creating this effect?
Do you have any images you can show?
What happens when you increase the Lens Radius of the spotlight and reduce the spot lights indirect visibility ?
Does changing the Filter Mode of the Gobo help?
I can suggest you to make two geometries with balls, one original, another with a refract with uncheck primal visibility, to work from the caustic balls, so you will get a caustic from the glass balls, and in the direct scenes will be original ones. But frame will become heavy.
Maybe this help you https://support.solidangle.com/display/A5AFMUG/Refractive+Caustics+using+an+Emissive+Shader
Or just render all the separate layers with Gobo and composite them.
It's all on the quick hand ...