Sports Car studio light render

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  03 March 2012
Sports Car studio light render

Hello everybody,

I am having some problems with lighting and reflexions setup. I have uploaded a render image of the car and a screen shot of my light and reflexion cards setup.

My main problem is that the portal light above the car does't blend in some parts (see the blue arrows on the image), it's all grainy.

I like how the portal light illuminates and creates shadows but I dont know if there is any way that it doesn't turne the glass white?

Why do my light cards reflect so strange over the car shader? I have used a layerd shader with a blinn and a lamberd for the card shader.

It would be grate if you could give me some advise on what to do

Than you!
  03 March 2012
No time to really critique but don't forget to use some specular only lights sometimes, that can help 'ping' certain areas.
  03 March 2012
Thank you for the advice RagingBull! I'll experiment with it and see what I come up with
  03 March 2012
Hi becken,

Since the wax is near mirror reflection, any softness to the reflection will either have to be from fresnel reflectance or falloff to the object being reflected. You may be better off disabling the portal light visibility from reflection and instead using a plane with a self-illuminating material. Then in the texture apply some falloff to the edges of the texture. Also, I'm not sure if you're using fresnel reflection, it doesn't look very apparent. Standard blinn shaders don't have fresnel reflection built into them so you'd have to use a ramp driven by facing ratio attached to your specular color. It looks like mental ray in your viewport image so I'd say for the wax layer you're better off using an mia material which has built in fresnel parameters.

Hope this all make sense and that I'm not rambling too much.

  03 March 2012
Thank you Dan for your help, I have been traying out all your suggestions but I haven't had good results because of different issues:

- I tried disabling the portal light visibility from reflection but I wasn't able to do so.
- I tried to combine the color ramp with a mia_material_x using a layerd shader through a color blend node and the result wasn't good at all. The problem is that the leyerd shader can only take a mia_material through the color, transparency or glow using the connection editor so I couldn't conect the mia_material as a refelctive overcoat. I've been searching the web for info with no results. What I did was to assign a mia_car_paint material to the car.

In stead of that I have used a normal area light as a mental ray light and it seems to make the trick. I have duplucated the area light, one with specular for all the parts of the car and one with out it for the glass.

I tried to do the same thing with the light that comes from the left but even though the car is unlinked from the specular light, the reflection still appears.

I still have to work on the textures and the lights but do you have any suggestions for my lighting?

Sorry for the long speach!
  03 March 2012
Hi Becken,

I should have mentioned that a portal light isn't necessary for this setup. And instead you're better off using an area light. If you apply a ramp set to box in the color of your light you should be able to get a nice falloff on the edges of the light source. Looks like there's a trace depth issue, if you look at the back tire of the car, it's really bright. I'm not sure if this is because a lights shadow trace depth is incorrect. Definitely getting better!

  03 March 2012
Hi Dan,

The are light seemed to work in Ed Whetstones DT-Commercial Design Concept tutorial but you can't see how he gets rid of that cloudy reflections.

As my back tire was so dark I though of linking it to my side area light but it seems that it doesn't work that well. Placing a light beside the tire creates unwanted reflections so I gues I'll have to render the tire separately. It is a pity that we can't link reflections as we do with lights.

Using a ramp in the light color slot is a great idea I hadn't thought about. I did that in the IBL I have created for the general reflections.

Thank you very much for your help, it has been very usefull!!
  03 March 2012
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