View Full Version : Trying to create photomontage in LW using 2D Photoshop "cutouts"

Bill K
09-24-2006, 03:33 PM
Does anyone know how I can place a "cutout" (of a person for ex.) from an image (done in Photoshop) onto a polygon as a planar projection, place that newly created LW object into a scene, and key out or use an alpha channel to get rid of the background so only the "cut-out" is visible? I have tried images with chromagreen backgrounds without success - I can not figure out how to "key out" the chromagreen - tried using the transparency channel and creating a clone of the image to get an alpha channel - when I click on "alpha only" in the Image Editor for the clone in the transparency channel, the clone turns all white.

Same result with trying to use an alpha channel to get rid of the "background": I've tried cloning the image and using the clone as a reference for using an alpha channel to get get rid of the background; when I click on "alpha only" for the clone, the entire image (clone) appears white.

This is similar to flying a camera through 3D layers in After Effects, viewing 2D image cut-outs; without the limitations of AE. Attached is render of the "cut-out" on a chromagreen background composited over one the Worley Labs Sasquatch demo scenes.

Thanks for any input, suggestions, solutions.

Bill K

09-24-2006, 04:18 PM
object/properties/render tab/clip map :)

(technically, you should be able to use what you have with your alpha channel, although without anymore info on your work flow, I can only recommend the above)

09-24-2006, 04:37 PM
T-Light is right, Clip maps are the way to go... unless you have semi-transparent areas in your images (then you have to use transparency, which renders a lot slower - you can combine both, it is a bit tricky to do though).
Load your RGBA (including a matching alpha channel) into the image editor in LW.
Clone twice.
Set one clone to be colour only, the other alpha only.
Use the alpha only as your clipmap, the colour only as your surface colour.
Make sure to use obe surface per object, since clip-maps are applied on a per surface basis.

Plug: I've used this technique ages ago on Ring of Fire to place hand drawn, animated cutouts in 3D scenes: http://www.flay.com/getarticle.cfm?articleid=2 - yeah, ages ago... those were the times ;)


Bill K
09-24-2006, 10:15 PM
Thanks for the replies. I did a planar projection of a 32 bit Targa image on a polygon and used the clip map with the image's alpha, obtaining the result I wanted. Even though I am starting with a 32 bit Targa or PNG image, if I clone that image in LW's Image Editor and select "Alpha only", the (clone) image turns all white. The only way I can get an alpha of the image is to create one in Photoshop, and bring everything into LW.

Thanks again for your replies, T-Light & Lightwolf.

Bill K

09-25-2006, 01:54 AM
Be careful with Photoshop here, depending on the version it doesn't save the transparency as alpha, but rather a separate channel, whcih you'll have to create manuall out of your transparency.


09-25-2006, 02:26 AM
The easiest way is to make a 24Bit image for the surface and a seperate 8Bit image for the cutout. LW doesn't work well with 32Bit images, thats why its more predictable when you seperate the image and the clip map.

Bill K
09-25-2006, 09:13 AM
Thanks for the additional follow-ups Lightwolf & ingo. I kept creating 32-bit Targa or PNG files in Photoshop CS2 and tried separating out the alpha in LW by first cloning the image, then selecting "alpha only" for the clone - only to see the ENTIRE image turn white. I have a Patrik Beck tutorial disc on compositing where that worked in LW in the tutorial; it didn't work for me with a 32-bit Targa. Attached is quick composite over a Worley Labs Sasquatch demo scene where I created a separate "alpha" image in Photoshop, and used that for the clip map.

Seems like the better the "cut-out", the better the overall result; including a nice feathering on the alpha for the image being used. The attached image doesn't have that; evidenced by the white residual on the edges; but I like the shadow.

I watched a Photoshop tutorial on lynda.com where the instructor did a cut-out using the pen tool, followed by some pretty intense masking techniques using the extract filter, and managed to mask out single hairs.

Anyway, I am getting closer to what I'm looking for -- thanks to all for your replies.

Bill K