A simple test to simulates a type of corrosion.

The render uses an ambient occlusion image as the pattern that in turn 
chooses between bronze or corrosion (modified by a mild slope pattern, 
and a bit of randomness supplied by bozo).

Looking at some real bronze statue photographs on the interwebs, I 
reckon I'm a long, long way from getting real corroded bronze, but at 
least the general direction looks promising...

The second image is the ambient occlusion pass.

Cheers,
Edouard.

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Attachments:
Download 'ao-test.jpg' (95 KB) Download 'ao-map.jpg' (49 KB)

Preview of image 'ao-test.jpg'

Preview of image 'ao-map.jpg'

Edouard Poor wrote:
> A simple test to simulates a type of corrosion.
> 
> The render uses an ambient occlusion image as the pattern that in turn 
> chooses between bronze or corrosion (modified by a mild slope pattern, 
> and a bit of randomness supplied by bozo).
> 
> Looking at some real bronze statue photographs on the interwebs, I 
> reckon I'm a long, long way from getting real corroded bronze, but at 
> least the general direction looks promising...
> 
> The second image is the ambient occlusion pass.
> 
> Cheers,
> Edouard.

And another one, this time I tried a high-pass filter on the ambient 
occlusion image before using it in the image to localise the placement 
of the corrosion/dirt/mold. I think the effect is a bit better for it.

What do you think?

Cheers,
Edouard.

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Attachments:
Download 'ao-test-3.jpg' (112 KB)

Preview of image 'ao-test-3.jpg'

48c1017b@news.povray.org...
> And another one, this time I tried a high-pass filter on the ambient
> occlusion image before using it in the image to localise the placement
> of the corrosion/dirt/mold. I think the effect is a bit better for it.
>
> What do you think?
>
> Cheers,
> Edouard.
>
I agree it's better (maybe due to textures as well as process on the 
occlusion image.
I see more moss than corrosion though :-)

Marc

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m_a_r_c wrote:

> I agree it's better (maybe due to textures as well as process on the 
> occlusion image.
> I see more moss than corrosion though :-)

Heh - that's why I changed the statue to cheesy marble - it looked more 
like moss or something else organic to me too.

> Marc 

Cheers,
Edouard.

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This one looks good indeed!

The metal in the previous image seems too shiny to me, in combination with 
the corrosion. You could try to tarnish it some more. Maybe the corrosion 
should be a paler greenish tint?

Thomas

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Edouard Poor <pov### [at] edouardinfo> wrote:
> What do you think?

I think you are on the right track! This last image looks good, but not like
bronze, IMO. More like turquoise. This could be due to my monitor's gamma
setting, though. How are you applying the image? Rune's illusion.inc?

Dirt-mapping is something I always go back to. Lately I've found that Blender
can produce good UV maps that you can burn ambient occlusion onto.

Keep up the good work. I look forward to seeing more interesting images from you
:)

Sam

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Samuel Benge wrote:
> Edouard Poor <pov### [at] edouardinfo> wrote:
>> What do you think?
> 
> I think you are on the right track! This last image looks good, but not like
> bronze, IMO. More like turquoise. This could be due to my monitor's gamma
> setting, though. How are you applying the image? Rune's illusion.inc?

Since the first one looked so little like bronze with corrosion, I tried 
  more of a stone with mold look for the second one.

I'm applying the image with Rune's illusion.inc - I only started using 
that a week or so ago, and there's so much that you can do with it! I 
tried to do the mapping myself, but failed badly - luckily there are 
plenty of people out there who are much better with maths than me...

Hmmm, just had a thought - I wonder if you can do this trick in a single 
pass using the camera_view pigment in Megapov? Divide the universe into 
the same scene twice, one with AO and one with final lighting, then 
camera_view + illusion.inc's maths to pull the AO data into a 
pigment_pattern? Sounds both doable, and far trickier than I could 
possibly pull off. :-)

> Dirt-mapping is something I always go back to. Lately I've found that Blender
> can produce good UV maps that you can burn ambient occlusion onto.

I downloaded Blender the other day. I'm frankly a little lost in it - I 
need to find some good tutorials or similar...

> Keep up the good work. I look forward to seeing more interesting images from you
> :)

Thank-you very much!

I'm still trying to get my head around your proximity and related SSS 
macros. Applying the AO image works nicely for some scenes, but your 
proximity macro is a global solution, and not just a camera specific one.

> Sam

Cheers,
Edouard.

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Edouard Poor <pov### [at] edouardinfo> wrote:
> I downloaded Blender the other day. I'm frankly a little lost in it - I
> need to find some good tutorials or similar...

I sympathise. If you just want ambient occlusion baking then maybe it's worth
looking at xnormal (http://www.xnormal.net/2.aspx). Either way, baking the
occlusion effect into texture maps is likely to be the most efficient solution
for all-mesh scenes (if you're lucky enough to have them).

Tom

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Edouard Poor wrote:
> I'm applying the image with Rune's illusion.inc - I only started using 
> that a week or so ago, and there's so much that you can do with it! I 
> tried to do the mapping myself, but failed badly - luckily there are 
> plenty of people out there who are much better with maths than me...

Rune's illusion.inc is *very* useful! I wonder if he knew how it would 
be used when he made it? I too tried to map an image to the viewing 
area, but failed miserably. Thank goodness he figured it out for us ;) 
He should get some sort of award for that file!

> Hmmm, just had a thought - I wonder if you can do this trick in a single 
> pass using the camera_view pigment in Megapov? Divide the universe into 
> the same scene twice, one with AO and one with final lighting, then 
> camera_view + illusion.inc's maths to pull the AO data into a 
> pigment_pattern? Sounds both doable, and far trickier than I could 
> possibly pull off. :-)

The camera pigment takes render options from the whole scene file. I 
suppose you could place a copy of the mesh in an ambient cube with 
radiosity applied, but you would have to use radiosity for the final 
image. But with MegaPOV, can't you turn radiosity off for certain 
objects? If so, you can probably do it without having to use radiosity 
for the final output.

> I downloaded Blender the other day. I'm frankly a little lost in it - I 
> need to find some good tutorials or similar...

I recommend that you don't give up on learning Blender. While looking at 
tutorials, keep your eye on the keyboard shortcuts, as they make the 
program much easier to use.

> I'm still trying to get my head around your proximity and related SSS 
> macros. Applying the AO image works nicely for some scenes, but your 
> proximity macro is a global solution, and not just a camera specific one.

But you can't use the proximity macro for mesh objects :( If POV 
supported calling inside() for mesh objects, it would work. I wish 
somebody would figure out a way to get inside() working with meshes!

Sam

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stbenge wrote:
> But you can't use the proximity macro for mesh objects :( If POV 
> supported calling inside() for mesh objects, it would work. I wish 
> somebody would figure out a way to get inside() working with meshes!

You can make solid meshes now, which *should* work with inside().

Define a mesh using the inside_vector modifier, and see if that works.

-- 
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

"Given a signal with a 2-Hz bandwagon, the Nyquil frequency must be 1-Hz 
to avoid aliening of the furrier transformer."
     -- phdcomics.com

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