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Redig
10-27-2006, 01:15 PM
Hello folks-

Here's an odd question that I hope somebody can answer...

I am creating a digital video effect (DVE) to be used in Tricaster, but don't worry, my question has very little to do with that. :)

What I have is a scene where I need to 'cut' a hole through the alpha channel of all objects. Specifically, I have a shape (it is cut out of an object) which I need to be able to 'see through' to the transparent background, like a cookie cutter. There is only a plane in the way.

Man this sounds really confusing.


Camera -----> object with viewing hole -----> plane -----> alpha 0 background

Short version: Can I make a surface which ignores all objects behind it and 'shows' the background (specifically a background of alpha 0)?


Please :help:

If anybody needs a better description, I will certainly try.

donny
10-27-2006, 02:36 PM
Hello can you post the scene or a example of what you are trying to do?

Redig
10-27-2006, 03:01 PM
Thank you for responding... I don't feel alone in the world. :D

Perhaps a screenshot will suffice? If not, I'll upload the scene itself. It is the basic setup from the DVECreation Kit with an added model.


In the picture, you can see the plane with the odd checkerboard (this will be Video Source A). The (transparent) background will be Source B. My goal is to be able to see Source B through the controller on the logo, while the logo comes toward the camera, and Source B becomes the whole shot. Now, once the logo fills the camera, problem is solved as I can just dissolve the checkerboard. But I am unsure of anyway to see the transparent background through the controller.

Also, this will be used with live video, so as far as I know, it has to be checkerboard for A, and transparent for B.

EDIT: I forgot to mention that the controller is completely cut out of the logo, I just have a grey plane behind it to serve as a backing (I was experimenting with trying to solve the problem).

Thanks

Ztreem
10-27-2006, 04:44 PM
I don't know if I got this right or if my suggestion is of any use. I just thought that maybe you can use a front projection with source B on the surface in the logo you want to appear transparent.

Redig
10-27-2006, 08:39 PM
I don't know if I got this right or if my suggestion is of any use. I just thought that maybe you can use a front projection with source B on the surface in the logo you want to appear transparent.


Thank you for responding, and for the suggestion. The problem is that this is for live video and I have nothing to 'project' onto the plane. Plus, as far as I've read, I need that green/black checkerboard for video A, and transparent (or the background as it is) for video B. But when I make the plane transparent, obviously it just makes it so the green/black checkerboard shows through instead of the transparent background. *Technically the checkerboard renders white for me, but that's beyond the point*

It seems like such a silly problem to have, but I can't resolve it.


By the way, I love that character in your avatar...is it yours?

Ztreem
10-28-2006, 02:39 AM
OK, Maybe you can use a front projected clipmap to make a hole in the green/black checkerboard and the logo, then it should be transparent so you can see the background.

Thanks! yes, It's my character, made in LW a year ago I think.

Redig
10-28-2006, 09:07 PM
OK, Maybe you can use a front projected clipmap to make a hole in the green/black checkerboard and the logo, then it should be transparent so you can see the background.

Thanks! yes, It's my character, made in LW a year ago I think.


Sounds promising... I'm really quite new to LightWave... could you perhaps give a simple overview of what you mean? Should the clipmap be applied to the checkerboard (if so, how is the clipmap in the shape of the controller)?

Sorry for my ignorance.

Thanks,
Redig


Heh, I picture the character causing all sorts of mischief.

Ztreem
10-29-2006, 02:09 AM
If you make all surfaces black and the controller surface white with diffusion at 0% and illumination at 100% and render that out to a picture. Then you reset your scene to as it is now and apply the rendered picture as a clipmap to the backgound plane. Now you have a controller shaped transparent hole.
I hope I make sense.

Redig
10-30-2006, 12:19 AM
If you make all surfaces black and the controller surface white with diffusion at 0% and illumination at 100% and render that out to a picture. Then you reset your scene to as it is now and apply the rendered picture as a clipmap to the backgound plane. Now you have a controller shaped transparent hole.
I hope I make sense.

Yea...makes perfect sense. A complication...this needs to be animated... do I just apply a different clipmap image for each frame of animation (since the logo changes size)?

I really appreciate all the help Ztreem.

Redig
10-30-2006, 12:55 AM
Nevermind... load it as a sequence in the image editor. This method should work... a big THANK YOU to Ztreem. :thumbsup:

Ztreem
10-30-2006, 02:40 AM
Yep! you're right just render out a sequence and load it as sequence and apply it as a clipmap. I'm glad I could help, good luck!

Redig
10-30-2006, 10:01 PM
Yep! you're right just render out a sequence and load it as sequence and apply it as a clipmap. I'm glad I could help, good luck!


All went well with it thanks to you. I didn't even need to worry about making the clip map controller shaped. Once I started thinking about your advice, I realized the small plane that was hidden behind the logo that could be seen through the controller could all be part of the clip map. I just rendered the scene with that plane as 100% luminous 0 diffuse, everything else black, and when that clip map was applied to the checkerboard, the logo covered the excess...if you get my meaning.

Again, a big thanks. And the customer was quite pleased.

redig

Ztreem
10-31-2006, 04:56 AM
Perfect, I'm glad I could help.