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Lightmap + base texture problem

Started by head_hunter Sep 3, 2005 at 7:22 AM 3 replies 1k views

Original Post

Sep 3, 2005 at 7:22 AM

Hi everyone. I have implemented a lightmapper and I face the following problem : The dark areas of the lightmaps (the ones which receive no light and are set to the ambient light intensity), when combined with the base texture, produce a final result which is too dark to see. I have tried setting the ambient light intensity to a very high value (140, 140, 140) which appears as bright grey on the bare lightmaps but the result is still too dark. Do you have any suggestions as to what I am doing wrong? I am using the OpenGL API. Thanks.

Tom

Sep 3, 2005 at 10:49 AM

Sounds like your shadowmap is too dark. Brighten it up a bit.

skillfreak

Sep 5, 2005 at 12:05 AM

um... this kind of reminds me of texture splatting. When your blending factors dont add up to one, you get very dark terrain (where this is a common application where texture splatting is performed). There is a texture splatting article on gamedev, and this is briefly mentioned.

hplus0603

Sep 5, 2005 at 12:11 AM

Are you sure that the light map and the base color map are the only things affecting the output data? You have turned off GL_LIGHTING? The first texture env mode is REPLACE and the second is MODULATE?

When used with light mapping, the color maps should typically be full-bright, which (inside Photoshop) will look WAY too bright. Make sure you brighten your color maps as much as possible.

Another thing you can try is something like a MODULATE2X blend mode; there's some extensions that let you do that.

head_hunter

Sep 5, 2005 at 6:50 PM

Quote:
Original post by hplus0603
Are you sure that the light map and the base color map are the only things affecting the output data? You have turned off GL_LIGHTING? The first texture env mode is REPLACE and the second is MODULATE?

When used with light mapping, the color maps should typically be full-bright, which (inside Photoshop) will look WAY too bright. Make sure you brighten your color maps as much as possible.

Another thing you can try is something like a MODULATE2X blend mode; there's some extensions that let you do that.

What do you mean by "first" and "second" texture? Are you referring to the textures in the GL_TEXTURE0_ARB and GL_TEXTURE1_ARB channels?

Secondly, what do you mean by color maps?

Thanks for your input so far!

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