Hi there,

I'm using the brick pattern to simulate the texture of ballistic nylon. Here's
the texture definition:

#local BallisticNylon = texture {
   pigment {brick color Black transmit .3, color Black transmit 1}
   scale <.05, .05, 1>
}

The texture is layered over another texture and then applied to a plane {z, 0}.
I noticed that when I render the image at 4000 x 3000 pixels then resize it to
1280 x 960 it looks great, but when I render it at 1280 x 960 it looks horrible.
The attached image shows what I mean. In both cases I'm using +am2 +r3. Am I
doing something wrong?

Regards,
Dave Blandston

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Attachments:
Download 'brick normal.png' (41 KB)

Preview of image 'brick normal.png'

Dave Blandston wrote:
> Hi there,
> 
> I'm using the brick pattern to simulate the texture of ballistic nylon. Here's
> the texture definition:
> 
> #local BallisticNylon = texture {
>    pigment {brick color Black transmit .3, color Black transmit 1}
>    scale <.05, .05, 1>
> }
> 
> The texture is layered over another texture and then applied to a plane {z, 0}.
> I noticed that when I render the image at 4000 x 3000 pixels then resize it to
> 1280 x 960 it looks great, but when I render it at 1280 x 960 it looks horrible.
> The attached image shows what I mean. In both cases I'm using +am2 +r3. Am I
> doing something wrong?
> 
> Regards,
> Dave Blandston
> 
> 
> ------------------------------------------------------------------------
> 

It looks like something akin to a moire pattern to me. Can you post an 
original 1280x960 image showing this problem?

Because the brick pattern is close to the resolution of the render (ie 
the mortar gaps are about 1 pixel across at 1280x960) the AA sampling is 
not good enough to correctly render the pattern. I suggest you look at 
the AA options in the manual section 2.1.2.8.4, especially the 
Antialias_Depth option.

Rarius

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Rarius <rar### [at] rariuscouk> wrote:
> It looks like something akin to a moire pattern to me. Can you post an
> original 1280x960 image showing this problem?
>
> Because the brick pattern is close to the resolution of the render (ie
> the mortar gaps are about 1 pixel across at 1280x960) the AA sampling is
> not good enough to correctly render the pattern. I suggest you look at
> the AA options in the manual section 2.1.2.8.4, especially the
> Antialias_Depth option.
>
> Rarius

That was the problem. Lowering the aa-threshold to +a0.0001 seems to have fixed
everything. Thanks for the suggestion!

Regards,
Dave Blandston

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