PDA

View Full Version : Shadow Big Pain with the shadows



pixelking
07-01-2006, 06:12 AM
Can someone please tell me if there is a way to render a shadow from an object that shows up on the ground and blends with a photograph in the B/G that does not need to be composited in post.
In other words...
I have a photo as a back drop.
I have an object and a ground plane.
I want to render the object and the shadow it casts but not see the plane in the final render.
Any help would be great thanks.

PK

Skinner3D
07-01-2006, 06:16 AM
I think this is a job for 'Super Alpha Channel Man':dance: This is exactly what alpha channels are for. Putting shadows into backdrop scenes. The only problem is, I have not used alphas yet.:o I know the Inside Lightwave books have good tutorials on this subject and I am sure you can look them up on the lightwave site or other sites. Sorry I couldn't help you more.

kruemel_1
07-01-2006, 06:43 AM
You can map the background also to your plane (with projection front). So you get your image as texture for your plane.

To cast a shadow tweak the luminosity and diffuse value of your plane so it matches the color of the background image and the shadow color from the other objects in the photo.
Or you Set the diffuse value of your plane to 100%, clone the shadow casting light and set it's intensity value to the negativ value. ( 80% -> -80%). In the ojects tab exclude all objects other than the plane. So the light influence on the plane is eliminated by the negative light. By changing the shadow color of the negativ light you can tweak your shadow color.

pixelking
07-01-2006, 11:53 AM
Thanks for the the tip. Never thought about the Frontal plane projection. The negative light thing is also new. I will give it a try.