View Full Version : Can't get specular from final gather renders

08-29-2008, 07:47 AM
Hi, I'm using a dome with an HDRI mapped to the diffuse and ambient channels to light a model. The lighting looks solid but I notice specular highlights never show up. Only when I create lights will the specularty begin to show on my model. The issue is that the lights combined with Final Gather lighting is too bright so I have to dim the HDRI resulting in a loss of the richness that HDRIs produce. Does Final Gathering not emit specular highlights? If would I go about getting specularity to show? Using maya 2008 and miss_fast_skin_maya Thanks.

08-29-2008, 10:42 AM
I don't know what your hdri looks like. But FG is mainly supposed to be used as indirect light/secondary light (even though it can be used as primary light too). Highlight mainly come from direct light. You can use a light that only emit specular and not adding any light to the scene. But I would try to find a way to use both hdri and some light (to cast shadows etc)

08-29-2008, 03:03 PM
specular highlights are a fake approximation of the reflection of the light source in the object material, they only work with an actual light in your scene, and the easiest thing to do would be to try and get a balance between fg ibl and regular lights. also where you planning on having shadows? because fg cannot do directional shadows either so you would need a regular light source for that too

however, some work arounds would be to add a geometry with a surface shader and a super white color (value above 1), if your shaders have a little bit of reflectivity then this object will show up kind of like a specular, kind of

also maybe give the mia_material a go

08-29-2008, 05:40 PM
Thanks guys, that answers everything. No wonder it's called secondary lighting. I managed to get the best results mixing the HDRI with some scene lights but didn't know if that was the right thing to do. I can just tweak the brightness and find a good balance. I also couldn't get shadows unless I added a light, now I know why. Thanks a lot.

08-29-2008, 11:40 PM
If you want your HDRI to cast shadows you have to activate 'use light' (not sure if this is what it's called, but it should have something to do with light) on the IBL Sphere. Maybe this solves the specularity problem as well.

08-30-2008, 01:46 PM
'use light' creates a grid of lights based on your hdr so that you can get an hdr lighting effect without using fg
i dont recommend it because a 200x50 (for example) grid of lights casting shadows is slow as all hell, and you really do need alot of lights to even approximate the hdr fg lighting especialy if your hdr has some bright details (interiors)

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