[Radiance-general] Measuring Illuminance

[Rob Guglielmetti]

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.
>
>
>
> Thanks & Regards,
> Raghu
>
>
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>
>
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