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jazzman121
10-28-2002, 10:40 PM
hey! does anyone do camera mapping here? i dont really understand how to do it in combustion.. can anyone help?

moovieboy
10-29-2002, 06:44 AM
Hey Jazz...

Hmmmm, interesting. Usually, camera mapping is pulled off within a "true" 3D application like Lightwave, Electric Image, etc, as opposed to a compositing program...

And, I don't think C* can expressly do this with a click... But there may be a way to manually work around it. It'll just take a lot of guesswork and eyeballing...

Similar principles apply as in 3D programs. I assume you want to take a 2D photo, apply it to simple geometry in 3D space and have some camera movement make it all seem real, yes?

First, here's a couple Web sites that explain camera mapping from a 3D program's POV...

There's DV Garage's tut on camera mapping:

http://www.dvgarage.com/garage/a2d/tut/tut.php

They even sell a camera mapping lab, but it's mainly for EI...

Then, here's Lightwave's:

http://lightwave3d.com/tutorials/rendering/camera_mapping/camera_mapping.html

I'm guessing you already know much of this, but I'm sure they'll also help others new to this...

Okay, now bringing that knowledge INTO combustion:

Unfortunately, my Combustion is crashing here at work, so this is more a theory. I hope I'm catching most of the problems in advance... if not, we'll all sweat out the problems together! :D

Say you've got a photo of a wall and blocks/crates like these tutorials did...

1) Duplicate your photo layer and call it "Crate A."

2) Make the crate layer semi-transparent so you can make out both layers...

Now, here's where the guesswork comes in.

3) Move the crate layer towards the camera along the Z axis... You're only moving it to where you THINK the real crate would be between you and the wall in the background layer. Don't pay attention to how the crate image changes, you're only going for position right now.

4) When you think you've got it, the crate photo is now bigger than the background layer, yes? You need to scale down the crate image until it matches the background layer (This is why it's semi-transparent.) When it looks good, make the crate layer opaque again. You should be able to click on and off the crate layer and the image looks unchanged...

5) Mask off the crate on the crate layer...

6) You'll eventually have to replace the background layer with one where you Photoshop-ed the crate out, depending on how strong the camera move is...


Now, this gets more and more... well, icky for things like floors and walls that are at an angle to the camera.

My guess would be that you physically orient a "wall" layer into 3D space first. Then besides scaling, you'd have to stretch, slant and distort the image on that wall to match the background's... Big pain, depending on how tough your shot is...

Or! Maybe you first put the 2D image in one comp, then bring that in as your "physical" wall in 3D space in a second comp. You stretch/distort the image in the first comp, until it looks good on your wall in the second comp! Did any of that make sense???

Hope this helps a little! Something tells me there's no easy way here... yet!

Now watch as someone says "Just click this filter here!" :D

-Tom

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