#bitmap shadows?
14 messages in this thread
Phil, Ya gotta help me. I'm doing something I thought would be a snap and it's
turning out to be an impossibility. On the first page of "Colorplate Samples"
in the r3 Reference Manual (right after page 8-152), image 8 shows opacity
mapping.
What I see there is a bitmap image (concen.tga) projected onto the solid
geometry of an umbrella, with a shadow-casting spotlight shining on the
geometry. The way the bitmap image drapes over the geometry determines the
appearance of the shadow, not the geometry itself.
I'm trying to do something that I think is very similar if not identical. I'm
trying to show trees on a site plan by mapping .TGA images of trees onto
rectangles and using ray-tracing spotlights to cast shadows of the trees, not
the rectangles. It's not working. I can remove the shadow of the rectangle OK,
and the image of the tree shows up OK, but I can't get the image of the tree to
cast a shadow. The only shadow I can get is of the rectangle. Yes, my light is
ray-traced. I've tried about a hundred possible combinations, but not the
right one.
I'm e-mailing you the very small .PRJ file I used for testing. When I started
trying to do this, I was using a 24-bit .TGA scanned tree and a 1-bit .TIF
conversion of the same tree as an opacity map. I replaced the tree .TGA and
.TIF w/ CONCEN.TGA off the WCT CD-ROM, so I'm not sending that.
I'll buy your R4 book if you can solve this <bg>. I've got the R3 edition, but
can't find the answer there.
Thanks very much for all your recent help. Joe Miller
Joe,
PMJI. You need another projector spotlight to project a shadow
image of the trees on the wall with all other objects excluded from it
to simulate shadows.
ME
Thanks Max, So it's all done w/ smoke & mirrors, eh? <g> I guess in a way it
may work better this way. Am I correct in thinking that the rendering time for
20-30 trees on a site would be less this way than if 3DS were actually able to
project the shadows through the bitmaps while rendering the rest of the scene?
Thanks for the help. Joe
PMJI Joe, but I think in order for your trees to cast "tree" shadows, you
may need to use a 1 bit opacity map along with the tree texture map. The
opacity map will cast the shadow, not the "tree" or the rectangle. I beleive
Phil's book for ver 3 mentions this on pages 326-327-328?. Hope this helps
til Phil gets back to you.
Marty Feldhaus
Thanks Marty
>> to cast "tree" shadows, you may need to use a 1 bit opacity map
I already had the opacity map. You know what the problem was? I wasn't
looking through a camera viewport!! I didn't know that the shadows
only appear when looking through a camera viewport.
I set up a camera viewport the next morning to check something else
and thought I was having some sort of seizure: There were the
shadows I had been busting my butt trying to get the night before.
Then I went back to the TOP viewport to look at them and they weren't
there. Even though I would have eventually rendered my scenes through
a camera viewport, it was very disturbing not to see the shadows in
the non-camera viewport.
I don't know where the camera limitation on bit-mapped shadows appears
in any documentation, but it sure doesn't appear where it is needed!!
This is disturbing! Jonaaaaaaas!!!! I wish for Shadows in
non-camera viewports!
The reason is, I've been contemplating rendering some TOP views of
sites w/ shadows for presentations. Generally, when an
architect/landscape architect colors up a site plan for presentation,
he/she draws cast shadows on it — and I was hoping to replicate
this.
I imagine I COULD put a camera very far away and do a Render/Blowup to
try to approximate an axonometric image (as opposed to the intense
three-point perspective that a normal aerial camera would produce,
but….
Dave, You realize that I'm only talking about bit-mapped shadows like
shadows through a bit-mapped tree, not *all* shadows. But if you're
doing landscape architecture, then maybe you're in trouble. Joe
Hmm, I guess I jumped to conclusions a bit, as obviously, you WERE only talking
about the lack of opacity-mapped shadows, and this, as you say, would generally
not be a problem. I was probably overdue for my hourly Coca-Cola fix! <G>
Sorry for freaking out!
Dave
<<.. wish?..>>
got it.
Dave:
It seems that doing straight overhead siteplan views which animate to
fly arounds are what I can expect as a standard request from my
office. I usually use camera viewports so the no shadows in the top
viewport problem is one I haven't heard of or experienced.
However, the quaternion forced role is another animal in need of
taming. I wish I could lock the roll on a camera even when near the
quaternion black hole. The suggestions to rotate the whole scene
have never worked for me as the fly around then gets the troubling
roll. Sure, you could move the world around and leave the camera
still but this just isn't intuitive for me. And while I'm at it, I
got one principal in our firm who seriously wants me to dump 3DS as
it can't do 2 point perspectives and he laughed at the render blow-up
fudge. Seems like a common complaint as when I worked for Philip
Johnson he hated the 3 point perspective views of the Times Square
project which would show the buildings leaning in if you happen to
raise your eye point above your target point. The render blowup is
not an option in tall interior spaces either even if you hide walls.
OK, I feel better now. <G>
<< I wish I could lock the roll on a camera even when near the quaternion
black hole. >>
got it.
You should'a just told "Phil" that it was his big-ol' glasses that
were causing the distortion!<G>
While you tend to have the same problems (of trying to capture
high/wide spaces) with normal (non-perspective-correcting) cameras,
it _would_ be nice to have more (easy to use)
architecturally-oriented image tools.
Back to Phil, it amazes me that so many architects (my own firm
included) are ready to dismiss something as useful as
3d-modeling/rendering/anim'ing based on one single item that doesn't
meet their expectation(s). "Oh, well, if it won't do THAT, then
what's the point?"
Dave:
/_______________________From your message________________________\\
"Oh, well, if it won't do THAT, then what's the point?"
__________________________________________________________________
Yeah, that's the sentiment I run into and it takes a bit of the wind out of
one's sails when encountered.
Bob
Joe –
Your welcome, and glad you were able to get it to work.
Now that you mention it the camera viewport does ring a bell. Also, correct
me if I'm wrong, a spotlight VPort will also render shadows? I'm not able to
check now, but try it.
Marty