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From: Jörg 'Yadgar' Bleimann
Subject: First attempts at blurred reflection...
Date: 27 Nov 2011 20:05:24
Message: <4ed2de54@news.povray.org>
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High!
As I want to have floor tiles with slightly disturbed reflection in my
Port Whatmough villa, I started to play around with the blurred
reflection hack described here:
http://wiki.povray.org/content/Knowledgebase:Language_Questions_and_Tips#Topic_13
Slightly disturbed reflection works quite well (see my test table
below), but I wonder how to achieve that strong, smooth blur I've seen
in so many scenes during the last years - using a large scaling factor
for the normal (e. g. 1000) yields weird results with high turbulence
values, while using small scaling factors like 0.001 gives something
remotely resembling my notion of blurred reflection, albeit still quite
grainy.
Should I try an even smaller scaling factor (0.0001 or so) and/or using
stronger anti-aliasing?
See you in Khyberspace!
Yadgar
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> Slightly disturbed reflection works quite well (see my test table
> below), but I wonder how to achieve that strong, smooth blur I've seen
> in so many scenes during the last years - using a large scaling factor
> for the normal (e. g. 1000) yields weird results with high turbulence
> values, while using small scaling factors like 0.001 gives something
> remotely resembling my notion of blurred reflection, albeit still quite
> grainy.
It looks to me like you're using just one single bumpy texture, rather
than multiple ones - or you've forgot to translate each of them
randomly; you need either multiple layers (e.g. 40 as in the example),
or - my personal preference - some slight but high-quality focal blur
for good oversampling (anti-aliasing doesn't quite cut it), in which
case a single small-scale bumpy texture will suffice.
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From: Jörg 'Yadgar' Bleimann
Subject: Re: First attempts at blurred reflection...
Date: 28 Nov 2011 08:10:54
Message: <4ed3885e$1@news.povray.org>
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Hi(gh)!
On 28.11.2011 04:05, clipka wrote:
> It looks to me like you're using just one single bumpy texture, rather
> than multiple ones - or you've forgot to translate each of them
> randomly; you need either multiple layers (e.g. 40 as in the example),
> or - my personal preference - some slight but high-quality focal blur
> for good oversampling (anti-aliasing doesn't quite cut it), in which
> case a single small-scale bumpy texture will suffice.
In fact I did so... here's the code:
#declare N_Blurred =
normal
{
bumps pow(10, div(clock, 5)-2)
turbulence pow(10, mod(clock, 5))
}
#declare F_Metallic =
finish
{
diffuse 1
brilliance 0.7
specular 1
roughness 0.001
reflection 0.5
metallic
}
#declare T_Blurred_Gold =
texture
{
average
texture_map
{
#while (i<40)
#declare rn=seed(0);
[1 pigment { color rgb <0.8, 0.75, 0> }
finish { F_Metallic }
normal { N_Blurred translate <rand(rn),rand(rn),rand(rn)>*100
scale 0.001 } ]
#declare i=i+1;
#end
}
}
// end of code
See you in Khyberspace!
Yadgar
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> Hi(gh)!
>
> On 28.11.2011 04:05, clipka wrote:
>
>> It looks to me like you're using just one single bumpy texture, rather
>> than multiple ones - or you've forgot to translate each of them
>> randomly; you need either multiple layers (e.g. 40 as in the example),
>> or - my personal preference - some slight but high-quality focal blur
>> for good oversampling (anti-aliasing doesn't quite cut it), in which
>> case a single small-scale bumpy texture will suffice.
>
> In fact I did so... here's the code:
> #declare T_Blurred_Gold =
> texture
> {
> average
> texture_map
> {
> #while (i<40)
> #declare rn=seed(0);
Heh! You're seeding the random number generator inside the loop, giving
you the very same sequence of "random" numbers (and hence the same
translation vector) over and over again. Don't do that :-P
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From: Jörg 'Yadgar' Bleimann
Subject: Re: First attempts at blurred reflection...
Date: 28 Nov 2011 17:23:20
Message: <4ed409d8@news.povray.org>
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Hi(gh)!
On 28.11.2011 16:19, clipka wrote:
> Heh! You're seeding the random number generator inside the loop, giving
> you the very same sequence of "random" numbers (and hence the same
> translation vector) over and over again. Don't do that :-P
Oh yes... it seems to be not a matter of stupidity, but of impatience!
Here's the correct table!
See you in Khyberspace!
Yadgar
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> Here's the correct table!
Yup, looks more like it :-)
As you may notice, turbulence doesn't add anything useful to it; neither
does a bump value of >> 1. The latter is because it causes lots of rays
to get reflected "into" the geometric object, which doesn't make sense,
so POV-Ray's algorithm replaces them with rays reflected according to
the unpertubed normal instead.
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