[Radiance-general] Measuring Illuminance

[Raghuram Kalyanam]

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 <jacobs.axel at gmail.com> 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 <kalyanam at rhrk.uni-kl.de> 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 <gregoryjward at gmail.com> 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 <kalyanam at rhrk.uni-kl.de>
>> 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 <gregoryjward at gmail.com> 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 <kalyanam at rhrk.uni-kl.de>
>> 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 <rob.guglielmetti at gmail.com>
>> 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
>> <raghuram.kalyanam at bauing.uni-kl.de> 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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