A grime shader would bring out the detail in a natural looking way.
Basically the color should get darker on concave areas where there is a 
large normal variance over a sampled area. You could limit this to normals 
within a certain range of "up" if you with to simulate the fallout of 
pollution collecting in surface details. 

Has anyone done this in POV yet?

Simon de Vet wrote:

> I've added some more detail to my bas relief of "INDUSTRY" for the Palace.
> I still want to detail the factory, but that should be fairly simple.
> 
> Three views attached: A neutral light viewing of the new, improved, panel,
> an overview of the Palace as it currently stands (with new plaza and third
> floor), and a detail view of the bas relief using the model lighting (a
> little too subtle for me. I think I'll have to use some textures to
> enhance it a bit.).
> 
> There are a total of 5 panels. I'm going to use stars for the first and
> last, and INDUSTRY accounts for one of the remaining three. For the
> others, I'm considering POLITIK and MILLITARY. I think that one of the
> MegaPov depth post-process may come in handy for generating some of the
> heightfields.
> 
> This is fun!
> 
> 
> -- Simon

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"Daniel Matthews" <lig### [at] bigpondnetau> wrote in message
news:352### [at] 3-enet...
> A grime shader would bring out the detail in a natural looking way.
> Basically the color should get darker on concave areas where there is a
> large normal variance over a sampled area. You could limit this to normals
> within a certain range of "up" if you with to simulate the fallout of
> pollution collecting in surface details.
>
> Has anyone done this in POV yet?

A gradient layered texture would do that, somewhat anyway.

> > This is fun!

And it also looks like fun.  I've been watching along the way.

Bob H.

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It already seems as if it's finished it will look great on a really large
render.  How much memory does it take right now?

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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Bob H. wrote:
>> A grime shader would bring out the detail in a natural looking way.
>> Basically the color should get darker on concave areas where there is a
>> large normal variance over a sampled area. You could limit this to
>> normals within a certain range of "up" if you with to simulate the
>> fallout of pollution collecting in surface details.
>>
>> Has anyone done this in POV yet?
> 
> A gradient layered texture would do that, somewhat anyway.

Have you an example or a URL for such a method?
I am still learning to translate into POV. :o)

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"Daniel Matthews" <lig### [at] bigpondnetau> wrote in message
news:182### [at] 3-enet...
> Bob H. wrote:
> >
> > A gradient layered texture would do that, somewhat anyway.
>
> Have you an example or a URL for such a method?
> I am still learning to translate into POV. :o)

// dirt accumulation texture example

light_source { <0, 100, -50>, 1 }

camera {
   location <0, 1, -10>
   look_at 0
}

#declare CSG=
union{
difference{
                plane {-z,0}
                cone {<0,0,-0.1>,5,<0,0,2>,2.5}
          }
                cone {<0,0,2>,2.51,<0,0,0>,0}
                texture {
                pigment{rgb<1,1,1>}
                finish {ambient 0.5 diffuse 0.5 specular 0.1 roughness 0.1}
                }
                texture {
                pigment{gradient z turbulence 0.1
                        color_map {
                                [0 color rgbf 1]
                                [0.75 color rgbf <0.7,0.67,0.6,1>]
                                [0.9 color rgbf <0.7,0.67,0.6,0.75>]
                                [1 color rgbf <0.7,0.67,0.6,0.5>]
                        } scallop_wave scale 4 translate z/4
                        }
                finish {diffuse 0.3 specular 0.05 roughness 0.15}
                }
          }

object {CSG rotate <0,45,0>}

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Bob H. wrote:

> "Daniel Matthews" <lig### [at] bigpondnetau> wrote in message
> news:182### [at] 3-enet...
>> Bob H. wrote:
>> >
>> > A gradient layered texture would do that, somewhat anyway.
>>
>> Have you an example or a URL for such a method?
>> I am still learning to translate into POV. :o)
> 
> // dirt accumulation texture example
> 
> light_source { <0, 100, -50>, 1 }
> 
> camera {
>    location <0, 1, -10>
>    look_at 0
> }
> 
> #declare CSG=
> union{
> difference{
>                 plane {-z,0}
>                 cone {<0,0,-0.1>,5,<0,0,2>,2.5}
>           }
>                 cone {<0,0,2>,2.51,<0,0,0>,0}
>                 texture {
>                 pigment{rgb<1,1,1>}
>                 finish {ambient 0.5 diffuse 0.5 specular 0.1 roughness
>                 0.1} }
>                 texture {
>                 pigment{gradient z turbulence 0.1
>                         color_map {
>                                 [0 color rgbf 1]
>                                 [0.75 color rgbf <0.7,0.67,0.6,1>]
>                                 [0.9 color rgbf <0.7,0.67,0.6,0.75>]
>                                 [1 color rgbf <0.7,0.67,0.6,0.5>]
>                         } scallop_wave scale 4 translate z/4
>                         }
>                 finish {diffuse 0.3 specular 0.05 roughness 0.15}
>                 }
>           }
> 
> object {CSG rotate <0,45,0>}

Thanks I will have a play with that. I gather that any detail that is cut 
to a certain depth exposes a darker part of the pigment, thus emulating 
dirt accumulation in all grooves of sufficient depth.

The problem is that grime deposits are normal variance dependent.
How can I have a texture in POV that is dependent on a calculation 
involving it's normal in relation to surrounding normal values?

Must I use POVMan and a renderman style shader?

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"Daniel Matthews" <lig### [at] bigpondnetau> wrote in message
news:128### [at] 3-enet...
>
> Thanks I will have a play with that. I gather that any detail that is cut
> to a certain depth exposes a darker part of the pigment, thus emulating
> dirt accumulation in all grooves of sufficient depth.

Yep, it's just a simple layered texture trick.

> The problem is that grime deposits are normal variance dependent.
> How can I have a texture in POV that is dependent on a calculation
> involving it's normal in relation to surrounding normal values?
>
> Must I use POVMan and a renderman style shader?

Since I'm almost positive official POV-Ray 3.1 has no ability to follow only
normals with patterns in any way that's probably a safe bet.  I just never
have used POVMan.  Although... MegaPOV does have a surface slope pigment
pattern, and also a post_process which can follow surface contours.  Has
trace() too.
BTW, I kind of lost track whether that bas relief remained as normals only
or were turned to CSG.  If only normals I'm uncertain if MegaPOV alone could
do anything then.
Anyone might know better than I do anyhow.

Bob H.

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This image illustrates a 'dust' texture I developed for my image in the
Worship round (tgq1984) of the IRTC.  Obviously the image on the left has
the dust applied while the one on the right does not.  The dust texture was
made using the MegaPOV slope pattern.

-tgq

""Bob H." <omn### [at] msncom> wrote in message
news:3b8ae83d@news.povray.org...
> "Daniel Matthews" <lig### [at] bigpondnetau> wrote in message
> news:128### [at] 3-enet...
> >
> > Thanks I will have a play with that. I gather that any detail that is
cut
> > to a certain depth exposes a darker part of the pigment, thus emulating
> > dirt accumulation in all grooves of sufficient depth.
>
> Yep, it's just a simple layered texture trick.
>
> > The problem is that grime deposits are normal variance dependent.
> > How can I have a texture in POV that is dependent on a calculation
> > involving it's normal in relation to surrounding normal values?
> >
> > Must I use POVMan and a renderman style shader?
>
> Since I'm almost positive official POV-Ray 3.1 has no ability to follow
only
> normals with patterns in any way that's probably a safe bet.  I just never
> have used POVMan.  Although... MegaPOV does have a surface slope pigment
> pattern, and also a post_process which can follow surface contours.  Has
> trace() too.
> BTW, I kind of lost track whether that bas relief remained as normals only
> or were turned to CSG.  If only normals I'm uncertain if MegaPOV alone
could
> do anything then.
> Anyone might know better than I do anyhow.
>
> Bob H.
>
>

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Attachments:
Download 'Dust.jpg' (35 KB)

Preview of image 'Dust.jpg'

Those gears look like they mesh a little too well to be Soviet-made.  ;)
Nice detail.

-- 
David Fontaine  <dav### [at] faricynet>  ICQ 55354965
My raytracing gallery:  http://davidf.faricy.net/

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On Thu, 30 Aug 2001 14:12:52 -0500, David Fontaine <dav### [at] faricynet>
wrote:

>Those gears look like they mesh a little too well to be Soviet-made.  ;)
>Nice detail.

Hehehe... allow me to know Soviet machine elements better :) After
all, until ten years ago there weren't any others around.

Early Soviet fighters had an auto-tracking gun which took into account
plane velocity, bullet speed & enemy relative velocity. It was very
effective and was purely mechanical - gears, eccentrics etc. How they
did that is a mystery to me, but it sure does tell a story.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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