Q: when using a 2-pass radiosity render and in the case normals need to be 
calculated, where should normal be set to on? In the first pass (saved)? or 
the second? or both?

Thanks!!

Thomas

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"Thomas de Groot" <t.d### [at] internlDOTnet> wrote in message 
news:487221a5$1@news.povray.org...
> Q: when using a 2-pass radiosity render and in the case normals need to be 
> calculated, where should normal be set to on? In the first pass (saved)? 
> or the second? or both?

it seems to make more sense having normal on during the 1st pass when your 
collecting rad data ..... sometime ago I remember a post that offered if you 
don't care about normals just turn it off as it slows things down. I did a 
small test and it does indeed.

just my 0.02 worth

Jim

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Jim Holsenback <jho### [at] hotmailcom> wrote:
> sometime ago I remember a post that offered if you 
> don't care about normals just turn it off as it slows things down. I did a 
> small test and it does indeed.

  Normals do indeed slow down radiosity, but they also make a difference
if normal perturbations are relevant and visible on the surfaces. Without
'normal on' (and without any actual light source) the surface is rendered
smooth, as if it didn't have any normal perturbation at all.

-- 
                                                          - Warp

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"Warp" <war### [at] tagpovrayorg> schreef in bericht 
news:48725533@news.povray.org...
> Jim Holsenback <jho### [at] hotmailcom> wrote:
>> sometime ago I remember a post that offered if you
>> don't care about normals just turn it off as it slows things down. I did 
>> a
>> small test and it does indeed.
>
>  Normals do indeed slow down radiosity, but they also make a difference
> if normal perturbations are relevant and visible on the surfaces. Without
> 'normal on' (and without any actual light source) the surface is rendered
> smooth, as if it didn't have any normal perturbation at all.
>

Exactly. In general, I never turn normals on in radiosity for that reason, 
and in many scenes it is not a big issue if normals are nor really shown.

However, now that I have a scene where normals would possibly play a part, I 
was wondering where to do that. As Jim writes, the 1st pass seems to make 
more sense, but it is also collected on a (much) smaller render so, in the 
final pass where normals are turned off, are we not going to miss something? 
I suppose everything depends on the size difference between 1st pass render 
and final render...

Thomas

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Thomas de Groot nous illumina en ce 2008-07-08 03:43 -->
> "Warp" <war### [at] tagpovrayorg> schreef in bericht 
> news:48725533@news.povray.org...
>> Jim Holsenback <jho### [at] hotmailcom> wrote:
>>> sometime ago I remember a post that offered if you
>>> don't care about normals just turn it off as it slows things down. I did 
>>> a
>>> small test and it does indeed.
>>  Normals do indeed slow down radiosity, but they also make a difference
>> if normal perturbations are relevant and visible on the surfaces. Without
>> 'normal on' (and without any actual light source) the surface is rendered
>> smooth, as if it didn't have any normal perturbation at all.
>>
> 
> Exactly. In general, I never turn normals on in radiosity for that reason, 
> and in many scenes it is not a big issue if normals are nor really shown.
> 
> However, now that I have a scene where normals would possibly play a part, I 
> was wondering where to do that. As Jim writes, the 1st pass seems to make 
> more sense, but it is also collected on a (much) smaller render so, in the 
> final pass where normals are turned off, are we not going to miss something? 
> I suppose everything depends on the size difference between 1st pass render 
> and final render...
> 
> Thomas
> 
> 
If the two passes are at much different scales, then, I think that you must turn 
normals on on the second pass, and maybe not on the first. The first pass will 
collect low frequencies from the normals, and the higher frequencies will be 
collected during the final pass.

-- 
Alain
-------------------------------------------------
Health is merely the slowest possible rate at which one can die.

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"Alain" <ele### [at] netscapenet> schreef in bericht 
news:48768b27@news.povray.org...
>>
> If the two passes are at much different scales, then, I think that you 
> must turn normals on on the second pass, and maybe not on the first. The 
> first pass will collect low frequencies from the normals, and the higher 
> frequencies will be collected during the final pass.
>
Hm, yes. That is what I suspected. I have tried the first case and normals 
are not really visible. I shall try this out. Thanks for the tip.

Thomas

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