Measuring Illuminance

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

Thanks & Regards,
Raghu

There are two basic methods for calculating illuminance with Radiance. You
can pass one or more points to rtrace, which will return a value(s) for
that specific point(s); the other way is to pass in a view to rpict, which
will return values for each pixel in the view. By default, both tools
return radiance. If you want illuminance, you need to request irradiance
instead of radiance, and then convert that output to illuminance using the
standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from
the specific image you attached to your question here. In this case, you'd
need to re-render the image as an irradiance image instead of a radiance
image, using the -i option to rpict. With that image, you could pass it
through falsecolor, producing a falsecolor illuminance map or flood plot of
the illuminance on all the (non-glazed) surfaces in the image. A second
option pipeline to falsecolor can plot isocontours on the original image
above. See the falsecolor manpage (
http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

···

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam < [email protected]> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at
certain view points in the room (radiance generated picture) below. Let me
also know which tools gives what kinds of results.

Thanks & Regards,
Raghu

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

Also, if you have an irradiance image and just want to know the illumination at a few points, you can (on Macs and other Unix-like systems) display the image with ximage and use the ‘l’ command to find values.

···

--
Randolph M. Fritz, Lighting Design and Simulation
+1 206 659-8617 || [email protected] <mailto:[email protected]>

On Feb 14, 2016, at 5:04 PM, Rob Guglielmetti <[email protected]> wrote:

There are two basic methods for calculating illuminance with Radiance. You can pass one or more points to rtrace, which will return a value(s) for that specific point(s); the other way is to pass in a view to rpict, which will return values for each pixel in the view. By default, both tools return radiance. If you want illuminance, you need to request irradiance instead of radiance, and then convert that output to illuminance using the standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from the specific image you attached to your question here. In this case, you'd need to re-render the image as an irradiance image instead of a radiance image, using the -i option to rpict. With that image, you could pass it through falsecolor, producing a falsecolor illuminance map or flood plot of the illuminance on all the (non-glazed) surfaces in the image. A second option pipeline to falsecolor can plot isocontours on the original image above. See the falsecolor manpage (http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam <[email protected] <mailto:[email protected]>> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

_______________________________________________
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

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image and convert that to illuminance using standard luminous efficacy. I have tried using rpict as you said, but it turned out a radiance(luminance) image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I guess rad calls rpict internally. But how could we pass -i argument to rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for corresponding to the pixels. Could you help me how to approach, or may be with an example.

Best Regards,
Raghu

···

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected]> wrote:

There are two basic methods for calculating illuminance with Radiance. You can pass one or more points to rtrace, which will return a value(s) for that specific point(s); the other way is to pass in a view to rpict, which will return values for each pixel in the view. By default, both tools return radiance. If you want illuminance, you need to request irradiance instead of radiance, and then convert that output to illuminance using the standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from the specific image you attached to your question here. In this case, you'd need to re-render the image as an irradiance image instead of a radiance image, using the -i option to rpict. With that image, you could pass it through falsecolor, producing a falsecolor illuminance map or flood plot of the illuminance on all the (non-glazed) surfaces in the image. A second option pipeline to falsecolor can plot isocontours on the original image above. See the falsecolor manpage (http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam <[email protected] <mailto:[email protected]>> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

_______________________________________________
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

Hi Raghu,

In the "rad" program, you may use the "render" variable to add the "-i" option needed for irradiance (illuminance) calculation.

-Greg

···

From: Raghuram Kalyanam <[email protected]>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 7:11:34 AM PST

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image and convert that to illuminance using standard luminous efficacy. I have tried using rpict as you said, but it turned out a radiance(luminance) image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I guess rad calls rpict internally. But how could we pass -i argument to rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for corresponding to the pixels. Could you help me how to approach, or may be with an example.

Best Regards,
Raghu

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected]> wrote:

There are two basic methods for calculating illuminance with Radiance. You can pass one or more points to rtrace, which will return a value(s) for that specific point(s); the other way is to pass in a view to rpict, which will return values for each pixel in the view. By default, both tools return radiance. If you want illuminance, you need to request irradiance instead of radiance, and then convert that output to illuminance using the standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from the specific image you attached to your question here. In this case, you'd need to re-render the image as an irradiance image instead of a radiance image, using the -i option to rpict. With that image, you could pass it through falsecolor, producing a falsecolor illuminance map or flood plot of the illuminance on all the (non-glazed) surfaces in the image. A second option pipeline to falsecolor can plot isocontours on the original image above. See the falsecolor manpage (http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam <[email protected]> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

(Looks like Greg & I are at the same spot in our inboxes)

From the manpage for falsecolor:

"Falsecolor produces a false color picture for lighting analysis. Input is a rendered Radiance picture. ... The default multiplier is 179, which converts from radiance or irradiance to luminance or illuminance, respectively. A different multiplier can be given with -m to get daylight factors or whatever."

So in the case of falsecolor, you don't need to do anything by default to get the photometric values. =) You DO however need to supply the proper input images. Greg just replied with how to do that with 'rad'. #teamwork

···

On 2/16/16, 8:11 AM, "Raghuram Kalyanam" <[email protected]<mailto:[email protected]>> wrote:

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image and convert that to illuminance using standard luminous efficacy. I have tried using rpict as you said, but it turned out a radiance(luminance) image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I guess rad calls rpict internally. But how could we pass -i argument to rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for corresponding to the pixels. Could you help me how to approach, or may be with an example.

Best Regards,
Raghu

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected]<mailto:[email protected]>> wrote:

There are two basic methods for calculating illuminance with Radiance. You can pass one or more points to rtrace, which will return a value(s) for that specific point(s); the other way is to pass in a view to rpict, which will return values for each pixel in the view. By default, both tools return radiance. If you want illuminance, you need to request irradiance instead of radiance, and then convert that output to illuminance using the standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from the specific image you attached to your question here. In this case, you'd need to re-render the image as an irradiance image instead of a radiance image, using the -i option to rpict. With that image, you could pass it through falsecolor, producing a falsecolor illuminance map or flood plot of the illuminance on all the (non-glazed) surfaces in the image. A second option pipeline to falsecolor can plot isocontours on the original image above. See the falsecolor manpage (http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam <[email protected]<mailto:[email protected]>> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

_______________________________________________
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

Hi Greg,

Please let me know how to use render here!! I tried

rad scene.rif & render=-i
rad scene.rif & render=rpict -i
rad scene.rif & render='rpict -i'

Nothing worked. Sorry for my ignorance. It would be help full if you could let me how to use that.

Is there anyway I could see the image in ximage and could know illuminance values for every pixel i hover or something similar.

Best Regards,
Raghu

···

On Feb 16, 2016, at 8:52 PM, Greg Ward <[email protected]> wrote:

Hi Raghu,

In the "rad" program, you may use the "render" variable to add the "-i" option needed for irradiance (illuminance) calculation.

-Greg

From: Raghuram Kalyanam <[email protected] <mailto:[email protected]>>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 7:11:34 AM PST

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image and convert that to illuminance using standard luminous efficacy. I have tried using rpict as you said, but it turned out a radiance(luminance) image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I guess rad calls rpict internally. But how could we pass -i argument to rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for corresponding to the pixels. Could you help me how to approach, or may be with an example.

Best Regards,
Raghu

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected] <mailto:[email protected]>> wrote:

There are two basic methods for calculating illuminance with Radiance. You can pass one or more points to rtrace, which will return a value(s) for that specific point(s); the other way is to pass in a view to rpict, which will return values for each pixel in the view. By default, both tools return radiance. If you want illuminance, you need to request irradiance instead of radiance, and then convert that output to illuminance using the standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from the specific image you attached to your question here. In this case, you'd need to re-render the image as an irradiance image instead of a radiance image, using the -i option to rpict. With that image, you could pass it through falsecolor, producing a falsecolor illuminance map or flood plot of the illuminance on all the (non-glazed) surfaces in the image. A second option pipeline to falsecolor can plot isocontours on the original image above. See the falsecolor manpage (http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam <[email protected] <mailto:[email protected]>> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

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

Your ampersand is in the wrong place -- it needs to go at the end of the command. The following should work:

  rad scene.rif "render=-i" &

The quotes aren't strictly necessary, but allow you to put spaces and multiple options into the render variable.

You can also add the render variable directly to your scene.rif file.

Cheers,
-Greg

···

From: Raghuram Kalyanam <[email protected]>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 3:21:41 PM PST

Hi Greg,

Please let me know how to use render here!! I tried

rad scene.rif & render=-i
rad scene.rif & render=rpict -i
rad scene.rif & render='rpict -i'

Nothing worked. Sorry for my ignorance. It would be help full if you could let me how to use that.

Is there anyway I could see the image in ximage and could know illuminance values for every pixel i hover or something similar.

Best Regards,
Raghu

On Feb 16, 2016, at 8:52 PM, Greg Ward <[email protected]> wrote:

Hi Raghu,

In the "rad" program, you may use the "render" variable to add the "-i" option needed for irradiance (illuminance) calculation.

-Greg

From: Raghuram Kalyanam <[email protected]>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 7:11:34 AM PST

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image and convert that to illuminance using standard luminous efficacy. I have tried using rpict as you said, but it turned out a radiance(luminance) image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I guess rad calls rpict internally. But how could we pass -i argument to rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for corresponding to the pixels. Could you help me how to approach, or may be with an example.

Best Regards,
Raghu

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected]> wrote:

There are two basic methods for calculating illuminance with Radiance. You can pass one or more points to rtrace, which will return a value(s) for that specific point(s); the other way is to pass in a view to rpict, which will return values for each pixel in the view. By default, both tools return radiance. If you want illuminance, you need to request irradiance instead of radiance, and then convert that output to illuminance using the standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from the specific image you attached to your question here. In this case, you'd need to re-render the image as an irradiance image instead of a radiance image, using the -i option to rpict. With that image, you could pass it through falsecolor, producing a falsecolor illuminance map or flood plot of the illuminance on all the (non-glazed) surfaces in the image. A second option pipeline to falsecolor can plot isocontours on the original image above. See the falsecolor manpage (http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam <[email protected]> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

_______________________________________________
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

Thanks Greg.

I have a weird problem, I tried to execute this earlier

rad scene.rif & it creates a process and then kills instantly.

where as

rad -o x11 scene.rif works normal.

Any reason why this could happen. I am using a Macbook pro, can this occur because of lack of memory ??

Best Regards,
Raghu

···

On Feb 17, 2016, at 12:31 AM, Greg Ward <[email protected]> wrote:

Your ampersand is in the wrong place -- it needs to go at the end of the command. The following should work:

  rad scene.rif "render=-i" &

The quotes aren't strictly necessary, but allow you to put spaces and multiple options into the render variable.

You can also add the render variable directly to your scene.rif file.

Cheers,
-Greg

From: Raghuram Kalyanam <[email protected] <mailto:[email protected]>>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 3:21:41 PM PST

Hi Greg,

Please let me know how to use render here!! I tried

rad scene.rif & render=-i
rad scene.rif & render=rpict -i
rad scene.rif & render='rpict -i'

Nothing worked. Sorry for my ignorance. It would be help full if you could let me how to use that.

Is there anyway I could see the image in ximage and could know illuminance values for every pixel i hover or something similar.

Best Regards,
Raghu

On Feb 16, 2016, at 8:52 PM, Greg Ward <[email protected] <mailto:[email protected]>> wrote:

Hi Raghu,

In the "rad" program, you may use the "render" variable to add the "-i" option needed for irradiance (illuminance) calculation.

-Greg

From: Raghuram Kalyanam <[email protected] <mailto:[email protected]>>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 7:11:34 AM PST

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image and convert that to illuminance using standard luminous efficacy. I have tried using rpict as you said, but it turned out a radiance(luminance) image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I guess rad calls rpict internally. But how could we pass -i argument to rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for corresponding to the pixels. Could you help me how to approach, or may be with an example.

Best Regards,
Raghu

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected] <mailto:[email protected]>> wrote:

There are two basic methods for calculating illuminance with Radiance. You can pass one or more points to rtrace, which will return a value(s) for that specific point(s); the other way is to pass in a view to rpict, which will return values for each pixel in the view. By default, both tools return radiance. If you want illuminance, you need to request irradiance instead of radiance, and then convert that output to illuminance using the standard luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from the specific image you attached to your question here. In this case, you'd need to re-render the image as an irradiance image instead of a radiance image, using the -i option to rpict. With that image, you could pass it through falsecolor, producing a falsecolor illuminance map or flood plot of the illuminance on all the (non-glazed) surfaces in the image. A second option pipeline to falsecolor can plot isocontours on the original image above. See the falsecolor manpage (http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam <[email protected] <mailto:[email protected]>> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at certain view points in the room (radiance generated picture) below. Let me also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

_______________________________________________
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

Raghu,

there is a short section on the use of the rad command in my Radiance
Tutorial (Section 6).
For ximage and illuminance readings, please see Chapter 5.5 in my
Radiance Cookbook.
Both documents are available on Jaloxa:
http://www.jaloxa.eu/resources/radiance/documentation/index.shtml

Regards

Axel

···

On 17 February 2016 at 07:16, Raghuram Kalyanam <[email protected]> wrote:

Thanks Greg.

I have a weird problem, I tried to execute this earlier

rad scene.rif & it creates a process and then kills instantly.

where as

rad -o x11 scene.rif works normal.

Any reason why this could happen. I am using a Macbook pro, can this occur
because of lack of memory ??

Best Regards,
Raghu

On Feb 17, 2016, at 12:31 AM, Greg Ward <[email protected]> wrote:

Your ampersand is in the wrong place -- it needs to go at the end of the
command. The following should work:

rad scene.rif "render=-i" &

The quotes aren't strictly necessary, but allow you to put spaces and
multiple options into the render variable.

You can also add the render variable directly to your scene.rif file.

Cheers,
-Greg

From: Raghuram Kalyanam <[email protected]>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 3:21:41 PM PST

Hi Greg,

Please let me know how to use render here!! I tried

rad scene.rif & render=-i
rad scene.rif & render=rpict -i
rad scene.rif & render='rpict -i'

Nothing worked. Sorry for my ignorance. It would be help full if you could
let me how to use that.

Is there anyway I could see the image in ximage and could know illuminance
values for every pixel i hover or something similar.

Best Regards,
Raghu

On Feb 16, 2016, at 8:52 PM, Greg Ward <[email protected]> wrote:

Hi Raghu,

In the "rad" program, you may use the "render" variable to add the "-i"
option needed for irradiance (illuminance) calculation.

-Greg

From: Raghuram Kalyanam <[email protected]>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 7:11:34 AM PST

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image
and convert that to illuminance using standard luminous efficacy. I have
tried using rpict as you said, but it turned out a radiance(luminance)
image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I
guess rad calls rpict internally. But how could we pass -i argument to
rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for
corresponding to the pixels. Could you help me how to approach, or may be
with an example.

Best Regards,
Raghu

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected]> > wrote:

There are two basic methods for calculating illuminance with Radiance. You
can pass one or more points to rtrace, which will return a value(s) for that
specific point(s); the other way is to pass in a view to rpict, which will
return values for each pixel in the view. By default, both tools return
radiance. If you want illuminance, you need to request irradiance instead of
radiance, and then convert that output to illuminance using the standard
luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from
the specific image you attached to your question here. In this case, you'd
need to re-render the image as an irradiance image instead of a radiance
image, using the -i option to rpict. With that image, you could pass it
through falsecolor, producing a falsecolor illuminance map or flood plot of
the illuminance on all the (non-glazed) surfaces in the image. A second
option pipeline to falsecolor can plot isocontours on the original image
above. See the falsecolor manpage
(http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam > <[email protected]> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at
certain view points in the room (radiance generated picture) below. Let me
also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

_______________________________________________
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

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

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Thanks Axel for the info, I will go through them and will get back , if I have any questions.
  
Best Regards,
Raghu

···

On Feb 17, 2016, at 10:30 AM, Axel Jacobs <[email protected]> wrote:

Raghu,

there is a short section on the use of the rad command in my Radiance
Tutorial (Section 6).
For ximage and illuminance readings, please see Chapter 5.5 in my
Radiance Cookbook.
Both documents are available on Jaloxa:
http://www.jaloxa.eu/resources/radiance/documentation/index.shtml

Regards

Axel

On 17 February 2016 at 07:16, Raghuram Kalyanam <[email protected]> wrote:

Thanks Greg.

I have a weird problem, I tried to execute this earlier

rad scene.rif & it creates a process and then kills instantly.

where as

rad -o x11 scene.rif works normal.

Any reason why this could happen. I am using a Macbook pro, can this occur
because of lack of memory ??

Best Regards,
Raghu

On Feb 17, 2016, at 12:31 AM, Greg Ward <[email protected]> wrote:

Your ampersand is in the wrong place -- it needs to go at the end of the
command. The following should work:

rad scene.rif "render=-i" &

The quotes aren't strictly necessary, but allow you to put spaces and
multiple options into the render variable.

You can also add the render variable directly to your scene.rif file.

Cheers,
-Greg

From: Raghuram Kalyanam <[email protected]>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 3:21:41 PM PST

Hi Greg,

Please let me know how to use render here!! I tried

rad scene.rif & render=-i
rad scene.rif & render=rpict -i
rad scene.rif & render='rpict -i'

Nothing worked. Sorry for my ignorance. It would be help full if you could
let me how to use that.

Is there anyway I could see the image in ximage and could know illuminance
values for every pixel i hover or something similar.

Best Regards,
Raghu

On Feb 16, 2016, at 8:52 PM, Greg Ward <[email protected]> wrote:

Hi Raghu,

In the "rad" program, you may use the "render" variable to add the "-i"
option needed for irradiance (illuminance) calculation.

-Greg

From: Raghuram Kalyanam <[email protected]>
Subject: Re: [Radiance-general] Measuring Illuminance
Date: February 16, 2016 7:11:34 AM PST

Hi Rob,

Thanks for your reply. Could you elaborate on how to get irradiance image
and convert that to illuminance using standard luminous efficacy. I have
tried using rpict as you said, but it turned out a radiance(luminance)
image.
I executed the below command.

rpict -vf Views/Scene_3.vf -av .5 .5 .5 -i scene.oct | falsecolor | ximage

(Basically I generated radiance pictures (previously) directly with rad, I
guess rad calls rpict internally. But how could we pass -i argument to
rpict in this case!! So i guess the above command might have some problem)

I got false-color image with a contours of luminance.

Any way I wanted Luminance and Illuminance in numerical values for
corresponding to the pixels. Could you help me how to approach, or may be
with an example.

Best Regards,
Raghu

On Feb 15, 2016, at 2:04 AM, Rob Guglielmetti <[email protected]> >> wrote:

There are two basic methods for calculating illuminance with Radiance. You
can pass one or more points to rtrace, which will return a value(s) for that
specific point(s); the other way is to pass in a view to rpict, which will
return values for each pixel in the view. By default, both tools return
radiance. If you want illuminance, you need to request irradiance instead of
radiance, and then convert that output to illuminance using the standard
luminous efficacy function.

Specifically, it sounds like you want to know how to get illuminance from
the specific image you attached to your question here. In this case, you'd
need to re-render the image as an irradiance image instead of a radiance
image, using the -i option to rpict. With that image, you could pass it
through falsecolor, producing a falsecolor illuminance map or flood plot of
the illuminance on all the (non-glazed) surfaces in the image. A second
option pipeline to falsecolor can plot isocontours on the original image
above. See the falsecolor manpage
(http://radsite.lbl.gov/radiance/man_html/falsecolor.1.html) for details.

On Fri, Feb 12, 2016 at 7:02 AM, raghuram kalyanam >> <[email protected]> wrote:

Hi Everyone,

I would like to know which is the best way to measure illuminance at
certain view points in the room (radiance generated picture) below. Let me
also know which tools gives what kinds of results.

<scene_Scene_3.jpeg>

Thanks & Regards,
Raghu

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