Jpg-compression was not very friendly to the roughness of the mortar, but I
think, this one is big enough for a technical-study.
I wonder if it's worth to follow this path further (and which way to go),
cause this simple scene with aa 0.3 needed 22 m 19 s on my PII 450 MHz (with
some other stuff running as well). It's one isosurface, using the
brick-pattern as a function and Jeff Lee's technique to give the bricks
individual colours. The textures still needs a lot of work.

What do you think?

Marc-Hendrik

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Attachments:
Download 'bricktest.jpg' (52 KB)

Preview of image 'bricktest.jpg'

Marc-Hendrik Bremer wrote:
> 
> Jpg-compression was not very friendly to the roughness of the mortar, but I
> think, this one is big enough for a technical-study.
> I wonder if it's worth to follow this path further (and which way to go),
> cause this simple scene with aa 0.3 needed 22 m 19 s on my PII 450 MHz (with
> some other stuff running as well). It's one isosurface, using the
> brick-pattern as a function and Jeff Lee's technique to give the bricks
> individual colours. The textures still needs a lot of work.
> 
> What do you think?
> 

It looks nice, but the brick pattern, like other color list patterns, is
not well suited for isosurfaces because of the infinite gradient problem. 
I think one could make a special continuous isosurface function similar to
the brick pattern to avoid this.  

The mortar looks a bit too 'glowing' maybe reduce the ambient component.  

BTW, what exactly is Jeff Lee's technique?

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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Christoph Hormann wrote:

> BTW, what exactly is Jeff Lee's technique?

http://www.gate.net/~shipbrk/raytrace/bricks.html

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Christoph Hormann schrieb in Nachricht <3A82FCC0.811759F2@gmx.de>...
>It looks nice, but the brick pattern, like other color list patterns, is
>not well suited for isosurfaces because of the infinite gradient problem.

Yes, that's what I wanted to try and tried to avoid - by adding a granite
pigment, I reduced the gradient to something like 22.

>I think one could make a special continuous isosurface function similar to
>the brick pattern to avoid this.
>
Perhaps I'll try that anyways, since I don't like that the brickpattern does
not alter in the z direction. I mean, those bricks are straight behind each
other, which is not, what I expect (but I don't know if they do it this way
in RL). OTOH I could achieve that with a repeat-warp with an offset, I
think.

>The mortar looks a bit too 'glowing' maybe reduce the ambient component.
>

Oops, thank you! I thought I had set the global ambient-value to 0 as usual,
but it wasn't. Hm, doesn't help that much, I'll have to lower the brightness
of the color a bit.

>BTW, what exactly is Jeff Lee's technique?
>

He takes a bozo-pattern and repeats and "offset"s to fit on the bricks. But
I just saw, that Ken allready posted the link to the tutorial ...

Marc-Hendrik

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Marc-Hendrik Bremer wrote:

> What do you think?

Superb,  except that I get the sense that a bump or distortion on one brick
continues in its next door neighboor, which is unrealistic.

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Marc-Hendrik Bremer wrote:
> 
> Yes, that's what I wanted to try and tried to avoid - by adding a granite
> pigment, I reduced the gradient to something like 22.
> 

That's the maximum gradient detected, but that does not mean much.  If you
decrease the accuracy value or increase the step between brick and mortar,
it will increase again.  

> [...]
> >
> 
> He takes a bozo-pattern and repeats and "offset"s to fit on the bricks. But
> I just saw, that Ken allready posted the link to the tutorial ...
> 

Thanks, also to Ken.

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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Greg M. Johnson schrieb in Nachricht <3A83113B.1DCCE9D2@my-dejanews.com>...
>Marc-Hendrik Bremer wrote:
>
>> What do you think?
>
>Superb,  except that I get the sense that a bump or distortion on one brick
>continues in its next door neighboor, which is unrealistic.
>

Thank you! Yes, the granite pigment I applied to the bricks was the same
over the whole wall. I think I solved that problem by treating the
granite-pigment-function like the colours of the bricks - I chopped it apart
by repeat warps. It's better now, but it takes even longer to render (some
80% for the non-antialiased version) .

Marc-Hendrik

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On Thu, 08 Feb 2001 21:08:32 +0100, Christoph Hormann
<chr### [at] gmxde> wrote:

>It looks nice, but the brick pattern, like other color list patterns, is
>not well suited for isosurfaces because of the infinite gradient problem. 

One can use the boxed pattern with three repeat warps to make
isosurface friendly bricks.


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

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Very impressive.The texture looks just fine to me. Only questions would be :
1) It looks like a depth of four bricks (on the top) - if so, they wouldn't
be laid in line like that and each brick should be deeper (in proportion to
the length).
2) The tops look too bumpy compared to real bricks, perhaps they just need
an indentation like you get in some bricks.
3) How about a proper bricklaying pattern e.g. Flemish Bond.
4) Mortar looks a bit grey and shiny to me (like chewing gum).

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Richard Morton schrieb in Nachricht <3a87b021$1@news.povray.org>...
>Very impressive.The texture looks just fine to me.

Thanks. I tend to think that bricks have no solid colour over the whole
side. OTOH it seems to greatly depend on the age of the bricks. Older ones
get more colourfull? Perhaps it's just that they had not that pure material
some decades ago.

>Only questions would be :
>1) It looks like a depth of four bricks (on the top) - if so, they wouldn't
>be laid in line like that and each brick should be deeper (in proportion to
>the length).

Yes, 4 rows. I agree, that they shold not be in lines. But since I'm still
using the brick pattern, that's what it gives me. I tried to warp the
pattern half a brick, but that did not work as expected, so I didn't follow
that path any further. Probably I had just to translate the pattern first
... perhaps I'll try again.
You think the proportions are not right? It's the default size 8 to 3  to
4.5 units (with mortar 0.5 units). I noticed, that there are differend sizes
out there (at least in older buildings. Which is the most commonly used
ratio?

>2) The tops look too bumpy compared to real bricks, perhaps they just need
>an indentation like you get in some bricks.

What would that indentation look like? I allready reduced the influence of
the granite-pattern a lot. The posted image was made with an orthographic
camera and a shadowless light source. This way it is hard to see, that the
bricks are that bumpy at all sides.

>3) How about a proper bricklaying pattern e.g. Flemish Bond.

I must admit, I don't know any. But since it could be worth to build another
brick-pattern for isosurfaces, it may be possible to realise differend
patterns. I don't like the idea to position some hundreds of
isosurface-bricks in a box of iso-mortar ( I just can't get these things
right), so I would need a proper pattern to do so.

>4) Mortar looks a bit grey and shiny to me (like chewing gum).


I changed it already, if it's better now, I don't know. At least it's
different now :-)

Thanks for the suggestions,

Marc-Hendrik

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