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davie563
05-07-2006, 08:08 AM
Hi, im making this wee video for a special effects class at University and im not sure how to do a certain bit. below is a wee render of the basic set up of the scene, im goin to have the car drive round the 2 beer cans then drive under the books. Im trying to get lightwave to render the shadow that is projected on the ground plane but get ride of the rest, Is there a way to tell it to render only the car and the shadow ontop of the video background ?

Cheers in advance,

ohhh also is there a better way to allign the floor, im not sure if i have it sitting right, i might model a cylinder and bring it in to match up with the cans to give me another thing to allign it with, Anybody got any other ideas ? im not really that into SFX so i just want to get it done for the hand-in

Cheers

kruemel_1
05-07-2006, 10:04 AM
To your first problem:
In the surface editor of the gound go to the Advanced tab and set the Alpha Channel to Shadow Density. So you get in the compositing only the shadows of your car opaque.

randomnumbers
05-08-2006, 12:31 AM
Are you trying to do this all in lightwave or are you exporting your lightwave render to a compositing app (ie after effects or similar)?
If you are doing it all in lightwave, then check out front projection mapping.
I did a quick google for tutorials and found one here:
http://www.simplylightwave.com/movie_pages/tutorial.mhtml?tut_id=10
I'm sure you can find more on google.
If you are exporting your render to a compositing or editing program, then do as kruemel_1 suggested. Then you can tell your compositor/editor to use the alpha channel information to overlay your render onto the video.
Hope that helps.

EDIT:
Just saw that the tutorial I mentioned isn't free. Didn't look deep enough.
Try this one from the newtek site instead (it is written for version 6.5, but the theory is the same and should work in your version ok)
http://www.newtek.com/products/lightwave/tutorials/rendering/camera_mapping/camera_mapping.html

SplineGod
05-08-2006, 02:23 PM
Hey Davie,
Heres a scene file you can check out.
The camera was adjusted to match the grid to edges in the background pic.
The rest you can pick arpart. The lighting is the key.