Interpolate BSDFs

Hello Everyone, Happy valentine's day

I am working with shading devices, creating "easy and understandable"
charts in order to allow people to choose one or the other. My idea is to
plot light (or solar) transmission, using the concept of BSDF.

I think Klems basis does not have the resolution I am looking for.
Accordingly, I thought on creating a Klems MF:2, MF:4, etc. basis, but that
might take too long.

Finally, I am evaluating on using genBSDF by analyzing only the center of
the patches (i.e. sending only parallel rays) and interpolating, in order
to get a smoother and better representation.

I know Greg worked with this and that it is a really non-straightforward
problem, so I wanted to know if there is any program that helps with
this... and also I would like to know if I am thinking this correctly.

AS ALWAYS, THANKS IN ADVANCE.

Germán Molina
Hunter Douglas Chile S.A

···

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cambios o sus consecuencias. Usted debe estar informado que la compania
puede hacer un seguimiento de sus mensajes electronicos y su contenido,
gracias.

*Confidentiality Notice:* The information contained in this email message,
including any attachment, is confidential and is intended only for the
person or entity to which it is addressed. If you are neither the intended
recipient nor the employee or agent responsible for delivering this message
to the intended recipient, you are hereby notified that you may not review,
retransmit, convert to hard copy, copy, use or distribute this email
message or any attachments to it. If you have received this email in error,
please contact the sender immediately and delete this message from any
computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do
destinatário. Sua utilização, não autorizada, constitui crime passível de
prisão. Todas as precauções possíveis foram tomadas para garantir que este
e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir
responsabilidade por nenhuma perda ou dano causado por este e-mail ou de
seus anexos, recomendamos que o destinatário utilize seus procedimentos de
antivírus antes de qualquer uso.

By the way, my idea would be to:

1.- genBSDF the BSDF of a product (klems basis, maybe Klems MF:N)
2.- from that matrix, interpolate and generate plots.

I will also have to deal with the loss of energy due to sharp light
sources...? That is something that I do not understand yet.

THANKS AGAIN, any comments welcome.

···

2014-02-14 10:23 GMT-03:00 CHI-German Molina <[email protected]>:

Hello Everyone, Happy valentine's day

I am working with shading devices, creating "easy and understandable"
charts in order to allow people to choose one or the other. My idea is to
plot light (or solar) transmission, using the concept of BSDF.

I think Klems basis does not have the resolution I am looking for.
Accordingly, I thought on creating a Klems MF:2, MF:4, etc. basis, but that
might take too long.

Finally, I am evaluating on using genBSDF by analyzing only the center of
the patches (i.e. sending only parallel rays) and interpolating, in order
to get a smoother and better representation.

I know Greg worked with this and that it is a really non-straightforward
problem, so I wanted to know if there is any program that helps with
this... and also I would like to know if I am thinking this correctly.

AS ALWAYS, THANKS IN ADVANCE.

Germán Molina
Hunter Douglas Chile S.A

--

*Nota de Confidencialidad:* Este mensaje incluído los archivos adjuntos son
confidenciales y pueden contener informacion privilegiada protegida por
ley. Si Ud. no es el destinatario, deberia abstenerse de copiarlo,
distribuirlo, divulgarlo o usar la informacion contenida. Por favor, avise
inmediatamente al emisor y borre este mensaje de su sistema. Los mensajes
electronicos son susceptibles de ser cambiados, infectados o adulterados
sin autorizacion. No asumimos responsabilidad alguna por ninguna clase de
cambios o sus consecuencias. Usted debe estar informado que la compania
puede hacer un seguimiento de sus mensajes electronicos y su contenido,
gracias.

*Confidentiality Notice:* The information contained in this email message,
including any attachment, is confidential and is intended only for the
person or entity to which it is addressed. If you are neither the intended
recipient nor the employee or agent responsible for delivering this message
to the intended recipient, you are hereby notified that you may not review,
retransmit, convert to hard copy, copy, use or distribute this email
message or any attachments to it. If you have received this email in error,
please contact the sender immediately and delete this message from any
computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do
destinatário. Sua utilização, não autorizada, constitui crime passível de
prisão. Todas as precauções possíveis foram tomadas para garantir que este
e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir
responsabilidade por nenhuma perda ou dano causado por este e-mail ou de
seus anexos, recomendamos que o destinatário utilize seus procedimentos de
antivírus antes de qualquer uso.

Hi German,

there will be no light loss. However interpolation does not increase resolution. Think of it as if you were taking a picture with a smartphone from the 90's - the overall average luminance may be correct, but you will never be able to add information on detail in between the pixels by interpolation. So if you want / need high resolution, run genBSDF accordingly.

Cheers, Lars.

···

By the way, my idea would be to:

1.- genBSDF the BSDF of a product (klems basis, maybe Klems MF:N)
2.- from that matrix, interpolate and generate plots.

I will also have to deal with the loss of energy due to sharp light sources...? That is something that I do not understand yet.

THANKS AGAIN, any comments welcome.

Hi Lars, Thanks a lot for the quick answer, but I think my question was not
really clear.

What I want to achieve is to get the directional transmitance from" any"
angle. Interpolating would allow me getting a continuous (although not
really exact) value. This is mainly for visualization purposes, not really
for getting exact values. By increasing the number of patches I would have
a better resolution, but still I would have "bins" and not a continuous
value.

I hope is clear. If it is too hard (i.e. there is not any program that does
it for me), I can just increase the number of bins, and just smooth the
final image.

Thanks a lot!

Germán

···

2014-02-14 12:01 GMT-03:00 Lars O. Grobe <[email protected]>:

Hi German,

there will be no light loss. However interpolation does not increase
resolution. Think of it as if you were taking a picture with a smartphone
from the 90's - the overall average luminance may be correct, but you will
never be able to add information on detail in between the pixels by
interpolation. So if you want / need high resolution, run genBSDF
accordingly.

Cheers, Lars.

> By the way, my idea would be to:
>
> 1.- genBSDF the BSDF of a product (klems basis, maybe Klems MF:N)
> 2.- from that matrix, interpolate and generate plots.
>
> I will also have to deal with the loss of energy due to sharp light
sources...? That is something that I do not understand yet.
>
> THANKS AGAIN, any comments welcome.
>

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

--

*Nota de Confidencialidad:* Este mensaje incluído los archivos adjuntos son
confidenciales y pueden contener informacion privilegiada protegida por
ley. Si Ud. no es el destinatario, deberia abstenerse de copiarlo,
distribuirlo, divulgarlo o usar la informacion contenida. Por favor, avise
inmediatamente al emisor y borre este mensaje de su sistema. Los mensajes
electronicos son susceptibles de ser cambiados, infectados o adulterados
sin autorizacion. No asumimos responsabilidad alguna por ninguna clase de
cambios o sus consecuencias. Usted debe estar informado que la compania
puede hacer un seguimiento de sus mensajes electronicos y su contenido,
gracias.

*Confidentiality Notice:* The information contained in this email message,
including any attachment, is confidential and is intended only for the
person or entity to which it is addressed. If you are neither the intended
recipient nor the employee or agent responsible for delivering this message
to the intended recipient, you are hereby notified that you may not review,
retransmit, convert to hard copy, copy, use or distribute this email
message or any attachments to it. If you have received this email in error,
please contact the sender immediately and delete this message from any
computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do
destinatário. Sua utilização, não autorizada, constitui crime passível de
prisão. Todas as precauções possíveis foram tomadas para garantir que este
e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir
responsabilidade por nenhuma perda ou dano causado por este e-mail ou de
seus anexos, recomendamos que o destinatário utilize seus procedimentos de
antivírus antes de qualquer uso.

Hi Germán,

Why not use a tensor tree output of genBSDF in this case? High resolution on incoming and outgoing angles where it matters is why it was developed. You can use the C routines to query the TT directly, or use bsdf2rad to generate a Radiance model for visualization.

Cheers,
-Greg

···

From: CHI-German Molina <[email protected]>
Date: February 14, 2014 8:17:12 AM PST

Hi Lars, Thanks a lot for the quick answer, but I think my question was not really clear.

What I want to achieve is to get the directional transmitance from" any" angle. Interpolating would allow me getting a continuous (although not really exact) value. This is mainly for visualization purposes, not really for getting exact values. By increasing the number of patches I would have a better resolution, but still I would have "bins" and not a continuous value.

I hope is clear. If it is too hard (i.e. there is not any program that does it for me), I can just increase the number of bins, and just smooth the final image.

Thanks a lot!

Germán

2014-02-14 12:01 GMT-03:00 Lars O. Grobe <[email protected]>:
Hi German,

there will be no light loss. However interpolation does not increase resolution. Think of it as if you were taking a picture with a smartphone from the 90's - the overall average luminance may be correct, but you will never be able to add information on detail in between the pixels by interpolation. So if you want / need high resolution, run genBSDF accordingly.

Cheers, Lars.

> By the way, my idea would be to:
>
> 1.- genBSDF the BSDF of a product (klems basis, maybe Klems MF:N)
> 2.- from that matrix, interpolate and generate plots.
>
> I will also have to deal with the loss of energy due to sharp light sources...? That is something that I do not understand yet.
>
> THANKS AGAIN, any comments welcome.
>

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

Nota de Confidencialidad: Este mensaje incluído los archivos adjuntos son confidenciales y pueden contener informacion privilegiada protegida por ley. Si Ud. no es el destinatario, deberia abstenerse de copiarlo, distribuirlo, divulgarlo o usar la informacion contenida. Por favor, avise inmediatamente al emisor y borre este mensaje de su sistema. Los mensajes electronicos son susceptibles de ser cambiados, infectados o adulterados sin autorizacion. No asumimos responsabilidad alguna por ninguna clase de cambios o sus consecuencias. Usted debe estar informado que la compania puede hacer un seguimiento de sus mensajes electronicos y su contenido, gracias.

Confidentiality Notice: The information contained in this email message, including any attachment, is confidential and is intended only for the person or entity to which it is addressed. If you are neither the intended recipient nor the employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that you may not review, retransmit, convert to hard copy, copy, use or distribute this email message or any attachments to it. If you have received this email in error, please contact the sender immediately and delete this message from any computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do destinatário. Sua utilização, não autorizada, constitui crime passível de prisão. Todas as precauções possíveis foram tomadas para garantir que este e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir responsabilidade por nenhuma perda ou dano causado por este e-mail ou de seus anexos, recomendamos que o destinatário utilize seus procedimentos de antivírus antes de qualquer uso.

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

Hello Greg, and thanks for your answer.

I did not know of the existence of bsdf2rad, I will try it soon... also, I
think I will forget about interpolating, haha.

Is it possible to integrate the outgoing radiation with TT??? My idea is
to just plot DIRECTIONAL transmittance, so people can choose one or another
shading device for their designs. I want to explore the posibility of
overlaying these plots with a solar plot of a certain location, and choose
a device that blocks the Solar Heat Gains when needed.

THANKS A LOT

···

2014-02-14 14:50 GMT-03:00 Greg Ward <[email protected]>:

Hi Germán,

Why not use a tensor tree output of genBSDF in this case? High resolution
on incoming and outgoing angles where it matters is why it was developed.
You can use the C routines to query the TT directly, or use bsdf2rad to
generate a Radiance model for visualization.

Cheers,
-Greg

*From: *CHI-German Molina <[email protected]>

*Date: *February 14, 2014 8:17:12 AM PST

Hi Lars, Thanks a lot for the quick answer, but I think my question was
not really clear.

What I want to achieve is to get the directional transmitance from" any"
angle. Interpolating would allow me getting a continuous (although not
really exact) value. This is mainly for visualization purposes, not really
for getting exact values. By increasing the number of patches I would have
a better resolution, but still I would have "bins" and not a continuous
value.

I hope is clear. If it is too hard (i.e. there is not any program that
does it for me), I can just increase the number of bins, and just smooth
the final image.

Thanks a lot!

Germán

2014-02-14 12:01 GMT-03:00 Lars O. Grobe <[email protected]>:

Hi German,

there will be no light loss. However interpolation does not increase
resolution. Think of it as if you were taking a picture with a smartphone
from the 90's - the overall average luminance may be correct, but you will
never be able to add information on detail in between the pixels by
interpolation. So if you want / need high resolution, run genBSDF
accordingly.

Cheers, Lars.

> By the way, my idea would be to:
>
> 1.- genBSDF the BSDF of a product (klems basis, maybe Klems MF:N)
> 2.- from that matrix, interpolate and generate plots.
>
> I will also have to deal with the loss of energy due to sharp light
sources...? That is something that I do not understand yet.
>
> THANKS AGAIN, any comments welcome.
>

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

*Nota de Confidencialidad:* Este mensaje incluído los archivos adjuntos
son confidenciales y pueden contener informacion privilegiada protegida por
ley. Si Ud. no es el destinatario, deberia abstenerse de copiarlo,
distribuirlo, divulgarlo o usar la informacion contenida. Por favor, avise
inmediatamente al emisor y borre este mensaje de su sistema. Los mensajes
electronicos son susceptibles de ser cambiados, infectados o adulterados
sin autorizacion. No asumimos responsabilidad alguna por ninguna clase de
cambios o sus consecuencias. Usted debe estar informado que la compania
puede hacer un seguimiento de sus mensajes electronicos y su contenido,
gracias.

*Confidentiality Notice:* The information contained in this email
message, including any attachment, is confidential and is intended only for
the person or entity to which it is addressed. If you are neither the
intended recipient nor the employee or agent responsible for delivering
this message to the intended recipient, you are hereby notified that you
may not review, retransmit, convert to hard copy, copy, use or distribute
this email message or any attachments to it. If you have received this
email in error, please contact the sender immediately and delete this
message from any computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do
destinatário. Sua utilização, não autorizada, constitui crime passível de
prisão. Todas as precauções possíveis foram tomadas para garantir que este
e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir
responsabilidade por nenhuma perda ou dano causado por este e-mail ou de
seus anexos, recomendamos que o destinatário utilize seus procedimentos de
antivírus antes de qualquer uso.
_______________________________________________
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

--

*Nota de Confidencialidad:* Este mensaje incluído los archivos adjuntos son
confidenciales y pueden contener informacion privilegiada protegida por
ley. Si Ud. no es el destinatario, deberia abstenerse de copiarlo,
distribuirlo, divulgarlo o usar la informacion contenida. Por favor, avise
inmediatamente al emisor y borre este mensaje de su sistema. Los mensajes
electronicos son susceptibles de ser cambiados, infectados o adulterados
sin autorizacion. No asumimos responsabilidad alguna por ninguna clase de
cambios o sus consecuencias. Usted debe estar informado que la compania
puede hacer un seguimiento de sus mensajes electronicos y su contenido,
gracias.

*Confidentiality Notice:* The information contained in this email message,
including any attachment, is confidential and is intended only for the
person or entity to which it is addressed. If you are neither the intended
recipient nor the employee or agent responsible for delivering this message
to the intended recipient, you are hereby notified that you may not review,
retransmit, convert to hard copy, copy, use or distribute this email
message or any attachments to it. If you have received this email in error,
please contact the sender immediately and delete this message from any
computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do
destinatário. Sua utilização, não autorizada, constitui crime passível de
prisão. Todas as precauções possíveis foram tomadas para garantir que este
e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir
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antivírus antes de qualquer uso.

Hi Germán,

You can compute the total hemispherical transmittance for a particular incident angle using the bsdf library, which is also reported to the standard error by bsdf2rad when you run it.

Best,
-Greg

···

From: CHI-German Molina <[email protected]>
Date: February 17, 2014 12:38:49 PM GMT+01:00

Hello Greg, and thanks for your answer.

I did not know of the existence of bsdf2rad, I will try it soon... also, I think I will forget about interpolating, haha.

Is it possible to integrate the outgoing radiation with TT??? My idea is to just plot DIRECTIONAL transmittance, so people can choose one or another shading device for their designs. I want to explore the posibility of overlaying these plots with a solar plot of a certain location, and choose a device that blocks the Solar Heat Gains when needed.

THANKS A LOT

2014-02-14 14:50 GMT-03:00 Greg Ward <[email protected]>:
Hi Germán,

Why not use a tensor tree output of genBSDF in this case? High resolution on incoming and outgoing angles where it matters is why it was developed. You can use the C routines to query the TT directly, or use bsdf2rad to generate a Radiance model for visualization.

Cheers,
-Greg

From: CHI-German Molina <[email protected]>
Date: February 14, 2014 8:17:12 AM PST

Hi Lars, Thanks a lot for the quick answer, but I think my question was not really clear.

What I want to achieve is to get the directional transmitance from" any" angle. Interpolating would allow me getting a continuous (although not really exact) value. This is mainly for visualization purposes, not really for getting exact values. By increasing the number of patches I would have a better resolution, but still I would have "bins" and not a continuous value.

I hope is clear. If it is too hard (i.e. there is not any program that does it for me), I can just increase the number of bins, and just smooth the final image.

Thanks a lot!

Germán

Wow, that is exactly what I was looking for. I will modify bsdf2rad in
order to get the Hemispherical transmittance (or reflectance) as the stdout.

So I should do, for every pixel´s incident Theta and Phi I want, the
following:

*bsdf2rad -t TT_bsdf.xml in_Theta in_Phi 2>
hemispherical_transmission.txt*

Thanks, Greg, as usual.

Germán

···

2014-02-17 18:55 GMT-03:00 Greg Ward <[email protected]>:

Hi Germán,

You can compute the total hemispherical transmittance for a particular
incident angle using the bsdf library, which is also reported to the
standard error by bsdf2rad when you run it.

Best,
-Greg

*From: *CHI-German Molina <[email protected]>

*Date: *February 17, 2014 12:38:49 PM GMT+01:00

Hello Greg, and thanks for your answer.

I did not know of the existence of bsdf2rad, I will try it soon... also,
I think I will forget about interpolating, haha.

Is it possible to integrate the outgoing radiation with TT??? My idea is
to just plot DIRECTIONAL transmittance, so people can choose one or another
shading device for their designs. I want to explore the posibility of
overlaying these plots with a solar plot of a certain location, and choose
a device that blocks the Solar Heat Gains when needed.

THANKS A LOT

2014-02-14 14:50 GMT-03:00 Greg Ward <[email protected]>:

Hi Germán,

Why not use a tensor tree output of genBSDF in this case? High
resolution on incoming and outgoing angles where it matters is why it was
developed. You can use the C routines to query the TT directly, or use
bsdf2rad to generate a Radiance model for visualization.

Cheers,
-Greg

*From: *CHI-German Molina <[email protected]>

*Date: *February 14, 2014 8:17:12 AM PST

Hi Lars, Thanks a lot for the quick answer, but I think my question was
not really clear.

What I want to achieve is to get the directional transmitance from" any"
angle. Interpolating would allow me getting a continuous (although not
really exact) value. This is mainly for visualization purposes, not really
for getting exact values. By increasing the number of patches I would have
a better resolution, but still I would have "bins" and not a continuous
value.

I hope is clear. If it is too hard (i.e. there is not any program that
does it for me), I can just increase the number of bins, and just smooth
the final image.

Thanks a lot!

Germán

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

--

*Nota de Confidencialidad:* Este mensaje incluído los archivos adjuntos son
confidenciales y pueden contener informacion privilegiada protegida por
ley. Si Ud. no es el destinatario, deberia abstenerse de copiarlo,
distribuirlo, divulgarlo o usar la informacion contenida. Por favor, avise
inmediatamente al emisor y borre este mensaje de su sistema. Los mensajes
electronicos son susceptibles de ser cambiados, infectados o adulterados
sin autorizacion. No asumimos responsabilidad alguna por ninguna clase de
cambios o sus consecuencias. Usted debe estar informado que la compania
puede hacer un seguimiento de sus mensajes electronicos y su contenido,
gracias.

*Confidentiality Notice:* The information contained in this email message,
including any attachment, is confidential and is intended only for the
person or entity to which it is addressed. If you are neither the intended
recipient nor the employee or agent responsible for delivering this message
to the intended recipient, you are hereby notified that you may not review,
retransmit, convert to hard copy, copy, use or distribute this email
message or any attachments to it. If you have received this email in error,
please contact the sender immediately and delete this message from any
computer or other data bank, Thank you.

A informação transmitida é confidencial e para conhecimento exclusivo do
destinatário. Sua utilização, não autorizada, constitui crime passível de
prisão. Todas as precauções possíveis foram tomadas para garantir que este
e-mail não contenha vírus. Uma vez que nossa empresa não pode assumir
responsabilidade por nenhuma perda ou dano causado por este e-mail ou de
seus anexos, recomendamos que o destinatário utilize seus procedimentos de
antivírus antes de qualquer uso.

Greg

I am sure there must be something simple I am missing but do you know why I would get significantly lower hemispherical transmittance figures from bsdf2rad than from BSDFviewer (e.g. for phi 0 theta 0 in bsdf2rad as compared to incident patch 1 in BSDFviewer)?

Kind regards

David Griffiths
M +44 (0) 7785 700160
W solaveil.co.uk

Hi Germán,

You can compute the total hemispherical transmittance for a particular incident angle using the bsdf library, which is also reported to the standard error by bsdf2rad when you run it.

Best,
-Greg

···

On 17 Feb 2014, at 21:55, Greg Ward <[email protected]> wrote:

From: CHI-German Molina <[email protected]>
Date: February 17, 2014 12:38:49 PM GMT+01:00

Hello Greg, and thanks for your answer.

I did not know of the existence of bsdf2rad, I will try it soon... also, I think I will forget about interpolating, haha.

Is it possible to integrate the outgoing radiation with TT??? My idea is to just plot DIRECTIONAL transmittance, so people can choose one or another shading device for their designs. I want to explore the posibility of overlaying these plots with a solar plot of a certain location, and choose a device that blocks the Solar Heat Gains when needed.

THANKS A LOT

2014-02-14 14:50 GMT-03:00 Greg Ward <[email protected]>:
Hi Germán,

Why not use a tensor tree output of genBSDF in this case? High resolution on incoming and outgoing angles where it matters is why it was developed. You can use the C routines to query the TT directly, or use bsdf2rad to generate a Radiance model for visualization.

Cheers,
-Greg

From: CHI-German Molina <[email protected]>
Date: February 14, 2014 8:17:12 AM PST

Hi Lars, Thanks a lot for the quick answer, but I think my question was not really clear.

What I want to achieve is to get the directional transmitance from" any" angle. Interpolating would allow me getting a continuous (although not really exact) value. This is mainly for visualization purposes, not really for getting exact values. By increasing the number of patches I would have a better resolution, but still I would have "bins" and not a continuous value.

I hope is clear. If it is too hard (i.e. there is not any program that does it for me), I can just increase the number of bins, and just smooth the final image.

Thanks a lot!

Germán

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

No, I have no idea why they should disagree. Maybe Andy has time to compare his code to the hemispherical scattering report I'm making in bsdf2rad:

      fprintf(stderr, "Hemispherical %s: %.3f\n",
        (output_orient > 0 ? "reflection" : "transmission"),
        SDdirectHemi(idir, SDsampSp|SDsampDf |
            (output_orient > 0 ?
             SDsampR : SDsampT), &myBSDF));

It's possible that Andy isn't using the same set of flags, and is missing some of the energy or counting both sides rather than just hemispherical transmission.

Cheers,
-Greg

···

From: David Griffiths <[email protected]>
Date: February 19, 2014 12:12:31 AM GMT+01:00

Greg

I am sure there must be something simple I am missing but do you know why I would get significantly lower hemispherical transmittance figures from bsdf2rad than from BSDFviewer (e.g. for phi 0 theta 0 in bsdf2rad as compared to incident patch 1 in BSDFviewer)?

Kind regards

David Griffiths
M +44 (0) 7785 700160
W solaveil.co.uk

On 17 Feb 2014, at 21:55, Greg Ward <[email protected]> wrote:

Hi Germán,

You can compute the total hemispherical transmittance for a particular incident angle using the bsdf library, which is also reported to the standard error by bsdf2rad when you run it.

Best,
-Greg

Hi David,

I'm getting near perfect agreement between the two programs.
Make sure you understand the front/back conventions for bsdf2rad:

This gives *back transmission* for the normal patch:
bsdf2rad -t mybsdf.xml 0 0 > myrad.rad

This gives *back reflection* for the normal patch:
bsdf2rad -p mybsdf.xml 0 0 > myrad.rad

This gives *front transmission* for the normal patch:
bsdf2rad -p mybsdf.xml 180 0 > myrad.rad

This gives *front reflection* for the normal patch:
bsdf2rad -t mybsdf.xml 180 0 > myrad.rad

And yes, when your theta is greater than 90 (to get front values) the
current behavior is that -t gives reflection and -p gives transmission
(not sure if this is expected!)

If you're still not getting agreement, send me your xml file in a separate
email.

Andy

···

On Tue, Feb 18, 2014 at 9:54 PM, Greg Ward <[email protected]> wrote:

No, I have no idea why they should disagree. Maybe Andy has time to
compare his code to the hemispherical scattering report I'm making in
bsdf2rad:

fprintf(stderr, "Hemispherical %s: %.3f\n",
(output_orient > 0 ? "reflection" : "transmission"),
SDdirectHemi(idir, SDsampSp|SDsampDf |
(output_orient > 0 ?
SDsampR : SDsampT), &myBSDF));

It's possible that Andy isn't using the same set of flags, and is missing
some of the energy or counting both sides rather than just hemispherical
transmission.

Cheers,
-Greg

*From: *David Griffiths <[email protected]>

*Date: *February 19, 2014 12:12:31 AM GMT+01:00

Greg

I am sure there must be something simple I am missing but do you know why
I would get significantly lower hemispherical transmittance figures from
bsdf2rad than from BSDFviewer (e.g. for phi 0 theta 0 in bsdf2rad as
compared to incident patch 1 in BSDFviewer)?

Kind regards

*David Griffiths*

*M* +44 (0) 7785 700160
W solaveil.co.uk

On 17 Feb 2014, at 21:55, Greg Ward <[email protected]> wrote:

Hi Germán,

You can compute the total hemispherical transmittance for a particular
incident angle using the bsdf library, which is also reported to the
standard error by bsdf2rad when you run it.

Best,
-Greg

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

Hi David,

I'm getting near perfect agreement between the two programs.
Make sure you understand the front/back conventions for bsdf2rad:

This gives *back transmission* for the normal patch:
bsdf2rad -t mybsdf.xml 0 0 > myrad.rad

This gives *back reflection* for the normal patch:
bsdf2rad -p mybsdf.xml 0 0 > myrad.rad

This gives *front transmission* for the normal patch:
bsdf2rad -p mybsdf.xml 180 0 > myrad.rad

This gives *front reflection* for the normal patch:
bsdf2rad -t mybsdf.xml 180 0 > myrad.rad

And yes, when your theta is greater than 90 (to get front values) the
current behavior is that -t gives reflection and -p gives transmission
(not sure if this is expected!)

If you're still not getting agreement, send me your xml file in a separate
email.

Andy

···

On Tue, Feb 18, 2014 at 9:54 PM, Greg Ward <[email protected]> wrote:

No, I have no idea why they should disagree. Maybe Andy has time to
compare his code to the hemispherical scattering report I'm making in
bsdf2rad:

fprintf(stderr, "Hemispherical %s: %.3f\n",
(output_orient > 0 ? "reflection" : "transmission"),
SDdirectHemi(idir, SDsampSp|SDsampDf |
(output_orient > 0 ?
SDsampR : SDsampT), &myBSDF));

It's possible that Andy isn't using the same set of flags, and is missing
some of the energy or counting both sides rather than just hemispherical
transmission.

Cheers,
-Greg

*From: *David Griffiths <[email protected]>

*Date: *February 19, 2014 12:12:31 AM GMT+01:00

Greg

I am sure there must be something simple I am missing but do you know why
I would get significantly lower hemispherical transmittance figures from
bsdf2rad than from BSDFviewer (e.g. for phi 0 theta 0 in bsdf2rad as
compared to incident patch 1 in BSDFviewer)?

Kind regards

*David Griffiths*

*M* +44 (0) 7785 700160
W solaveil.co.uk

On 17 Feb 2014, at 21:55, Greg Ward <[email protected]> wrote:

Hi Germán,

You can compute the total hemispherical transmittance for a particular
incident angle using the bsdf library, which is also reported to the
standard error by bsdf2rad when you run it.

Best,
-Greg

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

Andy

Thank you for this. I had the -t and -p options back to front (literally)! When I use your settings for front transmission I now get perfect agreement.

Kind regards

David Griffiths

Hi David,

I'm getting near perfect agreement between the two programs.
Make sure you understand the front/back conventions for bsdf2rad:

This gives back transmission for the normal patch:
bsdf2rad -t mybsdf.xml 0 0 > myrad.rad

This gives back reflection for the normal patch:
bsdf2rad -p mybsdf.xml 0 0 > myrad.rad

This gives front transmission for the normal patch:
bsdf2rad -p mybsdf.xml 180 0 > myrad.rad

This gives front reflection for the normal patch:
bsdf2rad -t mybsdf.xml 180 0 > myrad.rad

And yes, when your theta is greater than 90 (to get front values) the current behavior is that -t gives reflection and -p gives transmission (not sure if this is expected!)

If you're still not getting agreement, send me your xml file in a separate email.

Andy

No, I have no idea why they should disagree. Maybe Andy has time to compare his code to the hemispherical scattering report I'm making in bsdf2rad:

      fprintf(stderr, "Hemispherical %s: %.3f\n",
        (output_orient > 0 ? "reflection" : "transmission"),
        SDdirectHemi(idir, SDsampSp|SDsampDf |
            (output_orient > 0 ?
             SDsampR : SDsampT), &myBSDF));

It's possible that Andy isn't using the same set of flags, and is missing some of the energy or counting both sides rather than just hemispherical transmission.

Cheers,
-Greg

···

On 19 Feb 2014, at 18:59, Andrew McNeil <[email protected]> wrote:
On Tue, Feb 18, 2014 at 9:54 PM, Greg Ward <[email protected]> wrote:

From: David Griffiths <[email protected]>
Date: February 19, 2014 12:12:31 AM GMT+01:00

Greg

I am sure there must be something simple I am missing but do you know why I would get significantly lower hemispherical transmittance figures from bsdf2rad than from BSDFviewer (e.g. for phi 0 theta 0 in bsdf2rad as compared to incident patch 1 in BSDFviewer)?

Kind regards

David Griffiths
M +44 (0) 7785 700160
W solaveil.co.uk

On 17 Feb 2014, at 21:55, Greg Ward <[email protected]> wrote:

Hi Germán,

You can compute the total hemispherical transmittance for a particular incident angle using the bsdf library, which is also reported to the standard error by bsdf2rad when you run it.

Best,
-Greg

_______________________________________________
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