I just started to play with 3d modeling in strata 3d (I know I said that I was going to wait till after my plug was done, but I changed my mind) and it is easier than I remember...but I have a question about bump maps. How does the bump map tell the program where bumps are, is it darker=bump and lighter=dent or vis versa, or what?
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-Hail Pougan!
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Originally posted by Pougan:
**I just started to play with 3d modeling in strata 3d (I know I said that I was going to wait till after my plug was done, but I changed my mind) and it is easier than I remember...but I have a question about bump maps. How does the bump map tell the program where bumps are, is it darker=bump and lighter=dent or vis versa, or what?
**
Odd. I thought I just wrote this reply! :frown:
Bump maps are usually light=high, dark=low. In Bryce, Photoshop, probably plenty of other applications, you can use negative values so light=low and so forth. A bump map is applied like any other texture; mapped, tiled, oriented, etc.
Note please that bump maps fool the render engine by altering the surface normals (no, I'm not going to get into surface normals here!) They do not alter the underlying geometry -- generally, you can recognize a bump map through the smooth (un-bumped) edges on objects and the way shadows fall in straight lines across the bumps.
In those rare cases where this matters, a program like Amorphium can change the actual geometry. For most projects, though, the bump map is a huge saver of time and RAM .
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everywhere else, it's --
"Nomuse"
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Bump maps are usually light=high, dark=low. In Bryce, Photoshop, probably plenty of other applications, you can use negative values so light=low and so forth. A bump map is applied like any other texture; mapped, tiled, oriented, etc.
Cool, thanks.
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Note please that bump maps fool the render engine by altering the surface normals (no, I'm not going to get into surface normals here!)...
One thing though, were can I find out about surface normals?
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-Hail Pougan!
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Originally posted by Commander Arashi:
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Note please that bump maps fool the render engine by altering the surface normals (no, I'm not going to get into surface normals here!)
**
Thank you!
But, (url="http://"http://www.stratacafe.com/models/downloads/alien_tree/alien_tree.sit")here(/url) is a bump map model. Have fun. I downloaded it off of (url="http://"http://www.stratacafe.com")Strata Café(/url).
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Visit my (url="http://"http://www.madman80513.vze.com")Website(/url) -Newly redone
THE PENGUINS! THE PENGUINS!
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Originally posted by Pougan:
**One thing though, were can I find out about surface normals?
**
I've seen explanations before. Me, I didn't get it until I saw some of the math, in "Realistic Ray Tracing." Wait a few years, and my big tutorial on The Physics of Bryce might be fininshed. Or maybe it won't be! ^_^;;
Okay...in short, a surface normal is an imaginary line drawn perpendicular to the surface of a polygon. (In my tutorial, I intended to show penquins standing upright in the centers of all the polygons!) The render engine calculates the angle between the light source and this normal; more angle, less light -- just as less light falls on the ground above the Arctic Circle, for instance.
Now, a bump map changes this imaginary line until it is no longer perpendicular. In essentials, it tells the render engine to render part of the bright part of a shaded sphere as if it were on the more shady side of the sphere.
This is oversimplification, tho. For one thing, most programs interpolate surface normals across adjoining polygons to simulate a smooth surface. For another thing, the bump maps work best in the transition area; if you have a black and white bitmap it really won't show any bumps. Try anti-aliasing, or applying a little gaussian blur, before using it in your 3d application.
Are you less confused now? Or more? 
(I was just reading the massive picture-book "The Making of Riven." Lots of bump maps used there.)
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everywhere else, it's --
"Nomuse"
That does help. At least I now know how bump maps work, although, I think I need to play around with them in order to fully understand how all this works. One more thing, in Strata 3d, there appears to be a pre-exiting light source, how do I change or get rid of that?
Thanks.
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-Hail Pougan!
