I would be very keen to find the best way to achieve the following render setup:
I want to have (for example) 2 spheres. One is a simple diffuse sphere but the other is a reflective sphere that will reflect using an HDR image configured as a texture in the in the world settings.
I want the spheres to be sitting on a pure white plain with a pure white background. By pure white I mean that there is no shading other than the shadow from the spheres
Sound simple?
I want the reflective sphere to NOT reflect the white background (so that the HDR image shows even on the very edges, BUT I want the shadow (and AO) of the sphere to affect the white ground plane on which the spheres are sitting.
I don’t want to see a seam between the ground plane and the background.
Finally, I don’t want to have to shine zillions of lights at the ground to hide the shading.
The problem I have hit, is that if I make the ground plane shadow only, the HDR world environment shows through (even if I put a shadeless white plane just underneath the shadow only plane).
I can achieve the look I want by making the world settings pure white…but then I lose the HDR reflections in the chrome sphere. If I have a shadeless floor plane I get no shadows. If I have a normal diffuse floor plane then the whole floor ends up with a gradient of shadow that I have to “white-out” with multiple lights (tricky to do without whitening the sphere shadow also. If I have a shadeless white background plane, it reflects in the sides of the sphere
Perhaps someone can suggest a solution with Nodes/renderlayers that simplifies the task?
I think you should investigate the use of render layers, ans multiple scenes. You could for example, in another scene create a plane that receives shadows, then, using compositing nodes, in use the shadow pass with an alpha over node.
Long story short, use a lighting setup in one scene to get one effect(shadow pass), then another lighting effect in another scene for another effect(reflection pass), then composite.
It may not be necessary to use multiple scenes, but I find it convenient. Also, note that different scenes can have completely different render settings such as image size, OSA, and even image output format.
Tasks such as yours are ver5y simple once you begin to understasnd how the render pipeline works. Also, the way the buttons are laid ou on the render layers tab shows you the compositing order when you follow thyem from left to right and top to bottom.
I took the time to try out the renderlayers option and it proved to be quite easy in the end.
What worked:
Renderlayer 1 had an object (some of which was reflective) and a floor plane set to shadow only, with a sky using an HDRI image.
2 Renderlayer 2 had a white plane set to shadeless that was large enough to cover the camera view.
3 Used the alpha from layer 1 to show layer 2.
Its an example of the sort of thing I was hoping to achieve. I gave the example of the spheres just so that people might easily be able to give it a go themselves (if they wanted to try and help), but the pencil pretty much equates to the same task.
