Dear all,

I created a small video out of Jaime's office scene (obtained from:
http://www.ignorancia.org/en/index.php?page=The_office ). The video is available
here at www.doc.ic.ac.uk/~ahanda/output120fps.avi . As you may notice, the
radiosity is flickering a lot at the back of the room. To let you know how I
rendered this scene, I used the following arguments to the povray commandline
tool

(a) povray +I<input_file> +O<output_file> +W640 +H480 -d +RI<radiosity_file>
+RFO (for first pass)
(b) povray +I<input_file> +O<output_file> +W640 +H480 -d +RI<radiosity_file>
+RFI (for second pass)

I'm a bit clueless as to why this flickering is happening. Could you please
suggest me some ideas to help remove this flickering in the scene? Thanks a lot
for your patience.

Regards,
Ankur

Post a reply to this message

> Dear all,
>
> I created a small video out of Jaime's office scene (obtained from:
> http://www.ignorancia.org/en/index.php?page=The_office ). The video is available
> here at www.doc.ic.ac.uk/~ahanda/output120fps.avi . As you may notice, the
> radiosity is flickering a lot at the back of the room. To let you know how I
> rendered this scene, I used the following arguments to the povray commandline
> tool
>
> (a) povray +I<input_file>  +O<output_file>  +W640 +H480 -d +RI<radiosity_file>
> +RFO (for first pass)
> (b) povray +I<input_file>  +O<output_file>  +W640 +H480 -d +RI<radiosity_file>
> +RFI (for second pass)
>
> I'm a bit clueless as to why this flickering is happening. Could you please
> suggest me some ideas to help remove this flickering in the scene? Thanks a lot
> for your patience.
>
> Regards,
> Ankur
>
>

When using radiosity, the sampling tend to change for each render as 
they are taken, at least partly, at random.

You can increase the number of samples taken, even going over 2000. Use 
importance to get more samples for bright objects or patterned ones.
You controll importance as follow:
In a #default block: #default{radiosity{importance Default_Importance}}
In the objects: radiosity{importance Object_Importance}
If you use a large number of samples, controling the importance becomes 
crucial to get reasonable rendering times.
Bright objects and those used as light sources should have importance 1. 
A broad and uniform surface, like a wall or ceiling, can have importance 
0.01.

More samples will soften out the random noise.

You can use +wt1 to limit yourself to only one working thread, but the 
render time will increase as you can no longer benefit from multiple cores.

You can try a lower pretrace_end value. I often use pretrace_end 0.01, 
0.005 or even 0.0025.
Using a smaller value for low_error_factor may help. Default to 0.5, you 
can use something like 0.3 to 0.2.
You can try increasing nearest_count up to 20.

Post a reply to this message

Thanks Alain,

It does help tweaking various parameters and I got rid of the blotchiness I was
getting before although at the expense of rendering time. Wondering if there's a
way to render it quickly?

Cheers,
Ankur

Alain <aze### [at] qwertyorg> wrote:

> > Dear all,
> >
> > I created a small video out of Jaime's office scene (obtained from:
> > http://www.ignorancia.org/en/index.php?page=The_office ). The video is available
> > here at www.doc.ic.ac.uk/~ahanda/output120fps.avi . As you may notice, the
> > radiosity is flickering a lot at the back of the room. To let you know how I
> > rendered this scene, I used the following arguments to the povray commandline
> > tool
> >
> > (a) povray +I<input_file>  +O<output_file>  +W640 +H480 -d +RI<radiosity_file>
> > +RFO (for first pass)
> > (b) povray +I<input_file>  +O<output_file>  +W640 +H480 -d +RI<radiosity_file>
> > +RFI (for second pass)
> >
> > I'm a bit clueless as to why this flickering is happening. Could you please
> > suggest me some ideas to help remove this flickering in the scene? Thanks a lot
> > for your patience.
> >
> > Regards,
> > Ankur
> >
> >
>
> When using radiosity, the sampling tend to change for each render as
> they are taken, at least partly, at random.
>
> You can increase the number of samples taken, even going over 2000. Use
> importance to get more samples for bright objects or patterned ones.
> You controll importance as follow:
> In a #default block: #default{radiosity{importance Default_Importance}}
> In the objects: radiosity{importance Object_Importance}
> If you use a large number of samples, controling the importance becomes
> crucial to get reasonable rendering times.
> Bright objects and those used as light sources should have importance 1.
> A broad and uniform surface, like a wall or ceiling, can have importance
> 0.01.
>
> More samples will soften out the random noise.
>
> You can use +wt1 to limit yourself to only one working thread, but the
> render time will increase as you can no longer benefit from multiple cores.
>
> You can try a lower pretrace_end value. I often use pretrace_end 0.01,
> 0.005 or even 0.0025.
> Using a smaller value for low_error_factor may help. Default to 0.5, you
> can use something like 0.3 to 0.2.
> You can try increasing nearest_count up to 20.

Post a reply to this message

> Thanks Alain,
>
> It does help tweaking various parameters and I got rid of the blotchiness I was
> getting before although at the expense of rendering time. Wondering if there's a
> way to render it quickly?
>
> Cheers,
> Ankur
>
> Alain<aze### [at] qwertyorg>  wrote:

>>> Dear all,
>>>
>>> I created a small video out of Jaime's office scene (obtained from:
>>> http://www.ignorancia.org/en/index.php?page=The_office ). The video is available
>>> here at www.doc.ic.ac.uk/~ahanda/output120fps.avi . As you may notice, the
>>> radiosity is flickering a lot at the back of the room. To let you know how I
>>> rendered this scene, I used the following arguments to the povray commandline
>>> tool
>>>
>>> (a) povray +I<input_file>   +O<output_file>   +W640 +H480 -d +RI<radiosity_file>
>>> +RFO (for first pass)
>>> (b) povray +I<input_file>   +O<output_file>   +W640 +H480 -d +RI<radiosity_file>
>>> +RFI (for second pass)
>>>
>>> I'm a bit clueless as to why this flickering is happening. Could you please
>>> suggest me some ideas to help remove this flickering in the scene? Thanks a lot
>>> for your patience.
>>>
>>> Regards,
>>> Ankur
>>>
>>>
>>
>> When using radiosity, the sampling tend to change for each render as
>> they are taken, at least partly, at random.
>>
>> You can increase the number of samples taken, even going over 2000. Use
>> importance to get more samples for bright objects or patterned ones.
>> You controll importance as follow:
>> In a #default block: #default{radiosity{importance Default_Importance}}
>> In the objects: radiosity{importance Object_Importance}
>> If you use a large number of samples, controling the importance becomes
>> crucial to get reasonable rendering times.
>> Bright objects and those used as light sources should have importance 1.
>> A broad and uniform surface, like a wall or ceiling, can have importance
>> 0.01.
>>
>> More samples will soften out the random noise.
>>
>> You can use +wt1 to limit yourself to only one working thread, but the
>> render time will increase as you can no longer benefit from multiple cores.
>>
>> You can try a lower pretrace_end value. I often use pretrace_end 0.01,
>> 0.005 or even 0.0025.
>> Using a smaller value for low_error_factor may help. Default to 0.5, you
>> can use something like 0.3 to 0.2.
>> You can try increasing nearest_count up to 20.
>
>
>
>

You can get some spedup by carefully tweaking your importance for the 
various objects or parts.

Using a lower pretrace_end value can allow you to use slightly lower 
quality settings lesewhere, some times.

If you have some objects that don't realy contribute to the radiosity, 
using no_radiosity may help. Same as no_image, no_shadow and 
no_reflection but make the object invisible to radiosity computations.
Best reserved to some rather small but complex objects. May also be 
worth using on large, flat and colourless glass panes.

Using a two pass aproach, you can use a lower resolution with NO aa for 
the first pass.
You may try using some broad and low quality focal blur on the first pass.


Alain

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