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kukanani
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« on: 16. August 2007, 09:28:55 pm » |
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Speaking of which, what would be the best way to use a monochrome image as a bump map?
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Marvin Fröhlich
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« Reply #1 on: 16. August 2007, 09:49:50 pm » |
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Speaking of which, what would be the best way to use a monochrome image as a bump map?
You need shaders for Bumpmapping. I suggest to have a look at the PhongLighting demo. Currently I don't have enough time to investigate that topic more deeply. (But I will  ) Marvin |
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'n ddrylliog
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« Reply #2 on: 17. August 2007, 06:56:08 am » |
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Speaking of which, what would be the best way to use a monochrome image as a bump map?
Ohla. I don't see what you want from a monochrome image... it'd mean you have only 2 different height levels, which is somewhat limited... Or am I mistaken ? |
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Marvin Fröhlich
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« Reply #3 on: 17. August 2007, 08:46:53 am » |
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Ohla. I don't see what you want from a monochrome image... it'd mean you have only 2 different height levels, which is somewhat limited... Or am I mistaken ?
Well, I guess, he was speaking of a grayscale image, which is theoretically sufficient. Though a bumpmap image must be blueish (for some reason). It is just a result of the range of values, that is needed on it. Marvin |
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Marvin Fröhlich
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« Reply #4 on: 17. August 2007, 08:56:13 am » |
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Nope. Use normal mapping instead. Much better.
Don't you need a high-resolution geometry to generate the necessary information from? Can blender do that? I guess, you could not create such a wonderful effect like in the PhongLighting demo without having a model of (e.g.) the floor, which contains every slot and slice of wood. So bumpmapping might be easier to realize. Marvin |
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'n ddrylliog
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« Reply #5 on: 17. August 2007, 09:08:36 am » |
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Nope. Use normal mapping instead. Much better.
Don't you need a high-resolution geometry to generate the necessary information from? Can blender do that? Yes of course, Blender can do that easily, e.g. using multires + render baking I guess, you could not create such a wonderful effect like in the PhongLighting demo without having a model of (e.g.) the floor, which contains every slot and slice of wood. So bumpmapping might be easier to realize.
It *is* easier, but normal mapping is just way better. And really easy with Blender, also. |
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'n ddrylliog
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« Reply #6 on: 17. August 2007, 09:09:31 am » |
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Well, I guess, he was speaking of a grayscale image, which is theoretically sufficient.
Ah, but that's not the same thing.. Though a bumpmap image must be blueish (for some reason). It is just a result of the range of values, that is needed on it.
There is no requirement for the image to be of any color, it depends on the implementation of this effect... |
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'n ddrylliog
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« Reply #8 on: 17. August 2007, 10:05:50 am » |
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Very, very interesting.
So in fact "bump maps" and "normal maps" are just two different ways of storing data for "bump mapping".. but "normal maps" require less computation, since the data is ready to be used by the shader, whereas with a "bump map", you have to compute the normals anyway, from the height values..
Am I right ?
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Marvin Fröhlich
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« Reply #9 on: 17. August 2007, 12:07:39 pm » |
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Very, very interesting.
So in fact "bump maps" and "normal maps" are just two different ways of storing data for "bump mapping".. but "normal maps" require less computation, since the data is ready to be used by the shader, whereas with a "bump map", you have to compute the normals anyway, from the height values..
Am I right ?
No. That's not right. Normal mapping is one implementation of the "abstract" idea of bump mapping (as I understand it). So normal maps could be called bump maps (but not vice versa). Normal maps are the way to store normal data for normal mapping. These normal maps could be extracted from several sources. One possibility is to extract it from a bitmap and another way is to extract it from a highly detailed mesh. Marvin |
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kukanani
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« Reply #10 on: 17. August 2007, 03:45:09 pm » |
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OK, let's get it cleared up. Sorry for the confusion, I meant a grayscale image. If I had a grayscale image, would it be better to use the aforementioned GIMP plugin to make a blue-ish picture for normal mapping, or to use a grayscale image for bumpmapping?
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Marvin Fröhlich
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« Reply #11 on: 17. August 2007, 07:31:34 pm » |
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OK, let's get it cleared up. Sorry for the confusion, I meant a grayscale image. If I had a grayscale image, would it be better to use the aforementioned GIMP plugin to make a blue-ish picture for normal mapping, or to use a grayscale image for bumpmapping?
Hmm... I don't know. I've never used bumpmapping on my own. Just try it  . Marvin |
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'n ddrylliog
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« Reply #12 on: 18. August 2007, 07:53:08 am » |
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OK, let's get it cleared up. Sorry for the confusion, I meant a grayscale image. If I had a grayscale image, would it be better to use the aforementioned GIMP plugin to make a blue-ish picture for normal mapping, or to use a grayscale image for bumpmapping?
No need. You write the shader, you know how you should treat the data.. |
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'n ddrylliog
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« Reply #13 on: 18. August 2007, 08:00:58 am » |
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No. That's not right. Normal mapping is one implementation of the "abstract" idea of bump mapping (as I understand it). So normal maps could be called bump maps (but not vice versa). Normal maps are the way to store normal data for normal mapping. These normal maps could be extracted from several sources. One possibility is to extract it from a bitmap and another way is to extract it from a highly detailed mesh.
Well, in the sense that I've always heard it before (and which is wrong), the "bump mapping" means "adding relief to an object with an heightmap"... Now, as the Wikipedia article says : <<On a normal map instead of vectors calculated per-pixel through small coding it's stored as a certain color in the map. Then the same happens on the light's point and X and Y span.>> So in fact it's really the same tech, just working from different data ? But yeah, there are other sorts of normal mapping (e.g. parallax mapping, steep parallax mapping, relief mapping, displacement mapping).. |
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Marvin Fröhlich
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« Reply #14 on: 18. August 2007, 10:16:38 am » |
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So in fact it's really the same tech, just working from different data ?
Well, I understood it this way: It is the same kind of effect with different ways to achieve it. But of course I may be wrong . Marvin btw: with an heightmap
In languages like English you do pronounce the "h"  . |
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