Filter Forge - Normal map to height map conversion?

Zoltan Erdokovy

Posts: 204
Filters: 24

Would it be possible to make a filter which converts a
normal map to a height map? Crazy bump does it but I'd
rather have a FF filter. smile:)

EDIT: The NVIDIA PS plugin also has this feature but
its results are crap.

Posted: March 11, 2011 6:03 am

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jitspoe

Posts: 189
Filters: 27

Hm, I'm not sure if this would be possible with the way FF processes things on a per sample basis. You'd have to be able to keep track of the adjacent samples to build up the height map.

Posted: March 11, 2011 10:08 am

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Zoltan Erdokovy

Posts: 204
Filters: 24

Well, one can offset the input image a few times to get the neighbors.
It's not practical for hundreds of samples but for a dozen or so might
be fine.

But I don't know the theory behind the conversion so I have no idea how
many samples would be required.

Posted: March 11, 2011 10:20 am

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jitspoe

Posts: 189
Filters: 27

I would imagine the process is something like this:
- Have some arbitrary starting value
- Examine starting pixel/sample's normal to get the slope.
- Add/subtract to/from the value and set on adjacent pixels.
- Move to the next pixel and repeat.

If FF adds bitmap based map scripting, this, and pretty much anything, will be possible.

Posted: March 11, 2011 12:28 pm

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CorvusCroax

CorvusCroax

Posts: 1227
Filters: 18

Hey Zoltan,
Did you give this a try?

Posted: July 28, 2011 2:53 pm

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Zoltan Erdokovy

Posts: 204
Filters: 24

Nah, it's been a while since I had the time to
mess with FF. :\

Posted: July 28, 2011 3:13 pm

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SpaceRay

SpaceRay

Posts: 12299
Filters: 35

Quote
Zoltan Erdokovy wrote: Would it be possible to make a filter which converts a normal map to a height map?

Sorry for my ignorance about render maps, but what would be this useful for ?

What could you make by converting a normal map into a height map ?

Posted: August 9, 2012 3:26 am

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Zoltan Erdokovy

Posts: 204
Filters: 24

I made a normalmap of wrinkled cloth using this technique:
http://zarria.net/nrmphoto/nrmphoto.html

Looked great but a normalmap can not be used as a sculpting
brush, for that a height data is neccessary. Also, working
with a grayscale texture is much easier when it comes to
photoshop blending modes or retouching.

Posted: August 9, 2012 3:37 am

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Skybase

2D/3D Generalist

Posts: 4025
Filters: 76

Because normal maps give you directionality where as a height map gives you intensity values.

So if you have normal maps, you can't necessary get "height" where using a bump map (or height) won't get you the same level of detail as a normal map. Which is why converting between the two is useful.

In any situation a normal map can be used for relighting purposes. So for example if I render a scene with a normal-map pass, I can use that in programs like Nuke or After Effects (with a plugin) to pass the information and relight accordingly. This just gives you extra flexibility later when changes may become necessary due to alterations in plans or otherwise, where render times become intense.

I'm generalizing here so keep in mind some of the information is mildly simplified for discussion purposes. smile:p

Can get into very deep discussions regarding normal maps so smile:p

Posted: August 9, 2012 3:41 am

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SpaceRay

SpaceRay

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Thanks very much Skybase for explaining it basically, is good to know this coming from an expert like you.

I will have to learn about this

Posted: August 9, 2012 4:16 am

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SpaceRay

SpaceRay

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I have seen this from Inujima in this other thread

Quote
Inujima wrote: Even now integration can be achieved by using the Blur component. As an example, I made the filter that convert a height map to a normal map and returnd it to a height map again.

There is the filter to make this available in this thread > Integral Component

I do not know if this is what is asked here to convert a normal map to a bump map and this could be useful or not

Posted: August 9, 2012 4:28 am

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Skybase

2D/3D Generalist

Posts: 4025
Filters: 76

I did read that back in 2011 and yesh it's helpful to its own end.

I'd just honestly do this in a different, dedicated program however. It's doable, definately, but lua crashes FilterForge on the Mac version so it's basically smile:(