On 21-6-2018 4:45, Ton wrote:
> For my RMS Titanic project I use the brick pattern for the deck planking.
> 
> However there are gaps in the mortar lines.
> 
> Here is a test scene that shows the problem:
> 

[snip]

> My povray version is
> Persistence of Vision(tm) Ray Tracer Version 3.8.0-alpha.9606898.unofficial (g++
> 7.3.0 @ x86_64-pc-linux-gnu)
> 
> I have tried with maximum anit-aliasing (+a0.1 +r9), but I'm still having the
> gaps. Is there any way I can fix this?

There are two ways:

1) increase the mortar size. Crude solution and you will still find 
moire effects too.

2) Use stochastic anti-aliasing provided by UberPOV. This is, to my 
knowledge, the best way although it may slow down your render ultimately.

To use this:
1) download UberPOV at: https://github.com/UberPOV/UberPOV/releases/

2) Change #version 3.7; to #version unofficial patch 3.71;

3) Stochastic ant-aliasing is provided by choosing one of the following 
settings for your render (width and height to your convenience of course:
// +w800 +h600 +am3 +a0.1 +ac0.90 +r3
// +w800 +h600 +am3 +a0.01 +ac0.90 +r4
// +w800 +h600 +am3 +a0.01 +ac0.99 +r4
// +w800 +h600 +am3 +a0.01 +ac0.99 +r6

Explanation, in the words of Clipka:
[start citation]
As for the mode 3 oversampling, this mode is driven by a stochastic 
algorithm, similar to focal blur;
the +a parameter specifies the /variance/, and the +ac parameter 
specifies the /confidence/.

In layman's terms, the mode 3 is all about estimates: While it renders 
pixels over and over again,
it estimates (A) the colour of the pixel, (B) the error in the estimated 
colour,
i.e. how much it still differs from the actual value, and (C) the 
reliability of the error estimate.
The +a parameter specifies the maximum estimated error you are willing 
to accept, while the +ac parameter
specifies the minimum reliability you demand for that error estimate.

In even simpler terms, the +a parameter affects the amount of general 
noise in the resulting image,
while the +ac parameter affects the amount of speckle artefacts.

(Last not least, the +r parameter puts a hard maximum on the number of 
samples per pixel.
The effective limit is 4 to the power of the parameter value, making it 
approximately the same as
for a worst-case scenario in anti-aliasing mode 2.)
[end citation]

-- 
Thomas

Post a reply to this message