[Radiance-general] different methods on irradiance calculation

[Ali Fatoorechi]

Thanks guys.

Regards,

Ali Fatoorechi
MBS Survey Software Ltd

*62 High Street*


*SteyningWest SussexBN44 3RD*

*T +44 (0)1903 879323M +44(0)7830751409*
ali at surveymbs.com
www.surveymbs.com

On Wed, Apr 12, 2017 at 12:31 AM, Andy McNeil <mcneil.andrew at gmail.com>
wrote:

> Just a quick note about -aa 0.  I've found that illuminance result without
> the ambient cache is lower than the result with an ambient cache and the
> same simulation settings.  I recommend decreasing -lw substantially when
> -aa 0 is used. Convergence testing with a few points furthest from the
> window is always a good idea, particularly when using -aa 0.
>
>
>
> On Tue, Apr 11, 2017 at 1:04 PM, Greg Ward <gregoryjward at gmail.com> wrote:
>
>> Hi Ali,
>>
>> Multiprocessing is not supported under Windows using rtrace,
>> unfortunately.
>>
>> Mkillum is not advisable if you are just computing illuminance points.
>>
>> Turning interpolation off with rtrace (-aa 0) is a reasonable thing to do
>> for point calculations, especially if you have only a handful of values you
>> are computing.  The payoff for the ambient cache is when you have many
>> bounces and/or many calculation points.
>>
>> Best,
>> -Greg
>>
>> *From: *Ali Fatoorechi <ali at surveymbs.com>
>>
>> *Date: *April 11, 2017 12:24:01 PM PDT
>>
>>
>> Hi Guys,
>>
>> I am writing mainly to understand Radiance more on different methods on
>> irradiance calculation on surface point while maintaining accuracy and
>> speed.
>>
>> - I can use rtrace with irradiance interpolation turned on and rely on
>> high -ad( >1024) for direct light from sky.
>> running Radiance on Windows, it didn't seem to do run it in multi
>> processing(-n). I am not sure if this is supported on Windows?
>> Also breaking the points in chunks and running separate rtrace processes
>> didn't seem to speed it up much.
>> I don't go mad with -a numbers but the time tends to increase, sometimes
>> up to an hour for a room on complex models.
>>
>> - I tried mkillum to increase the speed/accuracy but as the model is all
>> triangles I get the "aiming failure" error messages,
>>  and it was mentioned in another post that triangles are poor choice for
>> light sources(due to the way Radiance samples
>> direct lighting.) I guess mkillum may not be advised in this case? also
>> the calc time increases linearly with with more illums in the model.
>>
>> - rtrace with interpolation switched off, seems to be pretty quick. but
>> as it is blind monte carlo there is a concern on accuracy on
>> direct lighting I guess(unless using high -ad). I have seen the window
>> glazing defined as glow in three phase method(and later to use genbsdf for
>> T).
>> I am not quite familiar but if glow material is part of the direct
>> lighting, would this make it a better approach than pure MC?
>>
>> thanks and apology for this long post,
>> Ali
>>
>>
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>
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