Hi,
   I've been making some renders and I realized that whenever I add a 
bump_map to a height field, the smoothing of the heightfield disapears 
and I get a very rough polygonized(?) surface...

Anyone know how I can have a bump_map plus a smooth heightfield?

Thanks,
   Xilo

-- 
Dedicated to audio/visual and interactive artwork.
http://www.geocities.com/simonlemieux/

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In article <3ED### [at] hotpopcom> , Xilo Musimene <xil### [at] hotpopcom>
wrote:

> Anyone know how I can have a bump_map plus a smooth heightfield?

You can't.  Both effects depends on modifications of the surface normal.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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> You can't.  Both effects depends on modifications of the surface normal.


Couldn't/Shouldn't the bump map just modify the smoothed normal instead of
the original surface normal?

 - Slime
[ http://www.slimeland.com/ ]

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In article <3ede0f01$1@news.povray.org> , "Slime" <slm### [at] slimelandcom> wrote:

>> You can't.  Both effects depends on modifications of the surface normal.
>
> Couldn't/Shouldn't the bump map just modify the smoothed normal instead of
> the original surface normal?

Actually, I have been wondering if this would work, too.  However, I am
skeptical if this would have the desired effect because the "smooth" effect
depends on the surface normal and averaging it would most likely undo the
"smooth" effect.  It might be worth trying with different contributions,
though...

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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In article <3ede0f01$1@news.povray.org>, "Slime" <slm### [at] slimelandcom> 
wrote:

> Couldn't/Shouldn't the bump map just modify the smoothed normal instead of
> the original surface normal?

That's what I'm wondering...the height field normal code handles the 
smoothing, and shouldn't interact with bump mapping, which is just a 
normal pattern. Do other normals do this? I can't find anything in the 
source that would explain it.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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In article <3ede195b$1@news.povray.org>,
 "Thorsten Froehlich" <tho### [at] trfde> wrote:

> Actually, I have been wondering if this would work, too.  However, I am
> skeptical if this would have the desired effect because the "smooth" effect
> depends on the surface normal and averaging it would most likely undo the
> "smooth" effect.  It might be worth trying with different contributions,
> though...

Just use the smoothed normal as input the the bump_map() function. It 
should be perturbed just like any other normal. If the normals line up 
seamlessly before being perturbed, they should remain seamless 
afterwards. Of course, the perturbing pattern itself will be evaluated 
over the flat surface of the triangle, which can probably give visible 
effects in some odd cases, but my feeling is that this will be rare.
I'm not sure what averaging you're speaking of, or how it could undo 
smoothing. It should "just work".
BTW, where is the code that does this?

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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> Just use the smoothed normal as input the the bump_map() function. It 
> should be perturbed just like any other normal. If the normals line up 
> seamlessly before being perturbed, they should remain seamless 
> afterwards. Of course, the perturbing pattern itself will be evaluated 
> over the flat surface of the triangle, which can probably give visible 
> effects in some odd cases, but my feeling is that this will be rare.
> I'm not sure what averaging you're speaking of, or how it could undo 
> smoothing. It should "just work".
> BTW, where is the code that does this?

I found something strange when rendering the image again, povray tells me:
Warning: Converting PNG image map to 8 bits/sample from higher bit depth.

I've rendered my height field with povray, specifying I wanted a PNG 
with 16 bit per color.  But even if my image is grayscale, povray 
outputs a RGB image of 48bpp;  is there a way to force the resulting 
image to grayscale instead of RGB and is there a way to read such a 
48bpp image for my heightfield...

I think this is The problem I have, I don't think bump_map has to do 
with it... now I render the image without bump_map and the same uglyness 
appears...

Thanks for any input, btw, I'll post images and code shortly, possibly 
within the next 12 hours... ;)

Thanks,
   Xilo

-- 
Dedicated to audio/visual and interactive artwork.
http://www.geocities.com/simonlemieux/

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In article <3ED### [at] hotpopcom>,
 Xilo Musimene <xil### [at] hotpopcom> wrote:

> I've rendered my height field with povray, specifying I wanted a PNG 
> with 16 bit per color.  But even if my image is grayscale, povray 
> outputs a RGB image of 48bpp;  is there a way to force the resulting 
> image to grayscale instead of RGB and is there a way to read such a 
> 48bpp image for my heightfield...

Specify hf_gray_16 in global_settings and POV will generate a 16-bit 
grayscale image.


> I think this is The problem I have, I don't think bump_map has to do 
> with it... now I render the image without bump_map and the same uglyness 
> appears...

So I've been running around the source code looking for a way to fix a 
problem that doesn't exist?

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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