Render in Environment Using a Photo

[brandonlynne]

Hello Everyone. Does Anyone have an effective work flow for rendering your products into a background image using Rhino and VRay? Products like Hypershot and even AliasStudio Hardware Shading do a great job of letting you composite in real-time.

The biggest issue is the ability of these programs to create a rendering in which the ground shadows are on a transparent floor. This way when you hit render, it does a quick composite.

So far my work flow in VRay is:
1. Create Object Model
2. Insert VRay floor, and apply white material with Alpa Contribute = 0
3. Place BG image in Viewport (using Viewport Properties > Wallpaper)
4. Line up object roughly in Rhino viewport
5. Load a GI and reflection Map HDRI that closely approximates lighting in the photo
6. Set Horizontal rotation values of GI and Reflection HDRI over and over and over until the light looks like it's coming from the right direction (is there a way to set both at once with Rhinoscript?)
7. Render Image with White floor (NO BG image applied in VRay options)
Save a JPG, a PNG, and a JPG of the alpha (product only)
8. In photoshop,
Composite background image and PNG rendering
Paste JPG (with floor data) into a new Channel, Adjust levels to make floor 100% white, and shadows gray, create selection, make new layer, fill with black, then use selection as a layer mask. This allows the shadows to be transparent, and works even better when layer is set to multiply.

Needless to say, this requires a lot of extra time, files, and programs. Is there a way to render out the floor shadows using channels or some other method so I could a composite directly using a background image in VRay alone?

[Micha_cg]

Re: Render in Environment Using a Photo

2. Insert VRay floor, and apply white material with Alpa Contribute = 0

Be careful, a bug cause that alpha contribute=0 cause, that the object is invisible for GI rays and the GI environment will be sampled instead.

[brandonlynne]

Re: Render in Environment Using a Photo

Thanks Micha, I've just been rendering on a white floor for simplicity, so I'll keep track of this once I am using more complicated environments.

Any idea how to get just the shadows captured on a surface without the surface itself? That's the real goal in this process. If I could just export the shadows applied to a surface instead of the rendered surface itself that would be perfect.