RPC - halo-effect and transparency

[Maciej]

Gentlemen,

I have several problems with my RPC-details...

1. tree (left) just PNG file, transparent Alpha. How to get rid of white pixels, it means how to make them semi-transparent? Now, using sensivity parameter, one see either transparent or not, no steps between...

2. tree (middle) - JPG file, color (white) transparent, but no "holes" in the tree-shape. Just white outskirts. How to make them transparent?

3. tree (right B&W) - RPC mask, (grayscale, background black) How to apply the tree-coloures to the white figure, keeping the nice transparency scale?

4. Shadow - should I use Monte-Carlo reflections?

Any help appreciated...

[akinlolu olugboji]

Are these archvision RPC's?

[Maciej]

Nope, I havn't used ArchiVision... Yet.

[Roy Hirshkowitz]

So what are these, decals? materials?   RPCs are specific products, trademarks of Archvision.  The answers to your problems are very different if these are RPCs.

[Maciej]

ok, my mistake. These are just nXt decals. I called them "RPC", didn't realize that's the specific product name. 

However, is it possible to solve this issue using just nXt and AutoCAD tools?

[Roy Hirshkowitz]

Alpha masking is almost always the right approach.  The decal will need to be tagged as double-sided for the shadows to work properly.  You'll need to do some editing of the decal in photoshop or eq. to get a better result in terms of the halo.  The color of the alpha masked area, at least in the vicinity of the tree boundary, should probably be changed to a green which is similar to the tree itself.  A blending tool may need to be used between the masked pixel and the tree edge to create more pixels with intermediate alpha.

If you can't figure it out, zip up the drawing and decals and either attach them to a forum message or upload them via the Support menu above.  I'll take a look.

[Maciej]

Roy,

I tried to figure it out, it seems to work more or less... The only point to clarify is how to achieve intermediate alpha channel?

[Roy Hirshkowitz]

The alpha mask is just a gray scale image like the other (color) channels.  It can be edited in your bitmap editor just like the other channels.  You may need to search a little bit toil figure out how to do it. It probably contains intermediate values already at the edges, but may require further blurring to look better.