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View Full Version : hard shadows, need advice.


fatblueduck
11-17-2004, 11:08 AM
I'm trying to find ways to manipulate shading. Blender's documentation (http://download.blender.org/documentation/html/) doesn't seem up-to-date with 2.35's user interface.

Here's my problem specifically. I've made a basic scene with blocks in it. Raytracing is on. The shadows that the blocks are casting are too dark (they are nearly black). I want to make the shadows softer. I can't seem to find an option for this in the light's menus. Ive also tried (without success) changing the material composition of the floor. I haven't used a cg program before, so I'm not sure what the problem is exactly or where I should try to fix it. Thanks for any help!

fatblueduck
11-17-2004, 05:54 PM
Okay, I didn't want to edit the post (I'm a new person here) and I didn't want to create a new one.

Let me first address the solution to the first proble, in case it might help someopne else.
Inside of the buf.shado tab, my clip-end and clip-start values were not correct. I had to expand the range between them.
Now I can render things.

Here is my new problem that I have been trying for several hours to solve.
for some reason, no matter what settings I change (including soft) the shadows are not rendering realistically. I wish I could post a picture here, but I don't how cool the moderators would be with that.
I'll try to explain it so that if someone understands this problem, they might help me.

first I should say that rayshadow makes clean shadows of the cubes. (I have a simple scene with cubes, planar floor, planar walls). Buf.Shadow is what I'm having the problem with.

the shadows that each cube gives off from a buf.shado rendering are incorrect.
the shading is very soft, and almost absent, up close beside the front-lower areas of the shapes
I'm going to try and draw this with text -very primitive sketch.


|
|
|
|_______<<<that is the correct shadow from a tall shape (viewed from a profile)
below is the incorrect shadow (the one kind that buf.shado is rendering)
|
|
|
| . _ ____

I hope that that makes some sense...

Apollux
11-17-2004, 11:17 PM
You really need to post a picture. I can't even imagine how your problem looks like.

Anyways, it seems from here that it is not a technical problem with the sadows, but with the lighting setup as a whole.

If you only got one single and strong key-light, of course you will get dark near black shadows. Try adding some indirect lighting here and there, it is more close to what happens in reallity and will produce better looking shadows.

A few hemi-lights with really low energy levels placed on strategic places will do wonders for you. The most logical place to start is putting those behind the shadow casting objects, but a lot of trial and error are needed.

Even better, do a search on GI domes and set up a simply one of those.


Don't feel down with the lights. 3D Lighthing is a hard as hell task. They even are entire books talking only about that. That is one of the reasons why GI Render Engines (like Yafray) are so popular nowadays, because they pretty much resolve the lighting for you.

harkyman
11-18-2004, 03:33 PM
I know what you're talking about with the shadow getting unnaturally lighter towards the base of the object. That's just one of the downsides of buffered shadows. You can try lowering the bias value - that should help.

Additionally, you may want to use the raytraced area light. It can give nicer soft results without the tweaking hassle you will put into getting your buffered shadows looking good. Of course, a properly tweaked buff spotlight will be much faster than a raytraced arealight...

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