different methods on irradiance calculation

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

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 <[email protected]>
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

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 <[email protected]> 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 <[email protected]>

*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

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

Thanks guys.

Regards,

Ali Fatoorechi
MBS Survey Software Ltd

*62 High Street*

*SteyningWest SussexBN44 3RD*

*T +44 (0)1903 879323M +44(0)7830751409*
[email protected]

···

On Wed, Apr 12, 2017 at 12:31 AM, Andy McNeil <[email protected]> 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 <[email protected]> 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 <[email protected]>

*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

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

And a quick trick that used to work is to run several iterations and average them, if you are only testing a single point.
It is more precise than a single shot.
G

···

On 12 Apr 2017, at 09:15, Ali Fatoorechi <[email protected]> wrote:

Thanks guys.

Regards,

Ali Fatoorechi
MBS Survey Software Ltd

62 High Street
Steyning
West Sussex
BN44 3RD
T +44 (0)1903 879323 <>
M +44(0)7830751409
[email protected] <mailto:[email protected]>
www.surveymbs.com <http://www.surveymbs.com/>
On Wed, Apr 12, 2017 at 12:31 AM, Andy McNeil <[email protected] <mailto:[email protected]>> 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 <[email protected] <mailto:[email protected]>> 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 <[email protected] <mailto:[email protected]>>
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

_______________________________________________
Radiance-general mailing list
[email protected] <mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general

_______________________________________________
Radiance-general mailing list
[email protected] <mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general