shading problem

#1

Hi could someone take a look at the image and maybe give me some tips on how to solve it?
Some information that might be useful:

-Im using depth map shadow
-I got 3 spotlights aimed at specific areas in the scene to create the shadows
-The shadows are made by shadow only lights
-And i light the scene with lights without shadows

I have tried to experiment but i cant find anything that really makes any difference.
And the one in the picture is not the only place this happen, the shadow only lights
seem to leave out certain areas.
Does anyone have any clue about this, that can help me, it would be
very appreciated.

Image here

#2

To be honest it’s nigh-on impossible to tell what exactly that image is supposed to be, but I’m going to assume that your problem is the fact that the shadow that runs about 10 degrees to the right of the vertical doesn’t quite meet the corner of the black cube. If that’s the case then it looks like your bias is too high. Reducing it should pull the shadow back toward the object again. Increasing your shadow map resolution wouldn’t hurt either.

#3

sorry, sometimes its easy to take for granted that everyone wont know as much as me about the issue :slight_smile:

You are right about my problem, thank you for the answer it helped me, but with a bias at 0
its still not completely accurate.
If i can ask another question, can the problem also be that i need to add more spotlights, and just focuse each of them to smaller areas??

#4

Potentially a silly question but needs to be asked…

Is the object that is casting the shadow resting on the object that is receiving the shadow?

A gap between the two would produce the result you are seeing.

#5

Not a bad question. Cause i light linked the buildings and it worked propperly
only for a couple of buildings where it looks good. On some other buildings the
the shadow still seem to overlap some places, and i think maybe they have a gap. I will try it out, thank you

#6

Sorry about my last reply here, i mixed up some posts…

Unfortunately i still have some problems, so ill try to explain little more closely.

Im lighting an outdoor scene, and im using spotlight with depthmap shadow
to try and simulate sunlight. I use several shadow only spot light to make det shadowmap on different objects,
and one other spotlight to make the main light.

I feel like i have tried everything: Bias, filter etc, adjusted the distance of the light
from the objects, and adjusted cone angle. It has improved abit,
but an uneven shadow that dont hit directly at the corner of the building (like in the image above) wont go away no matter what i try, it seems.

Well in this case, its not very noticable when i render it from a distance. But what if
i needed to see it up close? I really want to know how to make it perfect…
Does anyone have any more tips for me? Is it possible to make it perfect the way im doing it??

Any more answers would be very helpfull, thank you…

#7

Have you tried increasing the resolution of your maps? A couple of things, if you’re simulating the sun, you really need to use a directional light, not a spotlight. Also, have you tried raytraced shadows? They would be much better for this effect than depth-map shadows.

#8

ok i see, thanks. Yes i have tried around in resolution as well.
Reason i used spotlight is cause i read that with a narrow cone, and the
spotlight placed far away it could simulate sunlight, but it didnt really goo deep
into it, just that i would have more controll over it with spotlight. I guess it dont really
work perfectly, but maybe can work if its not up close.
I think i move over to directional then and see how that goes.
Im using depthmap cause i want to learn it better, but ill try raytrace later :slight_smile:

Thanks…

#9

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