Thank you very much, Jan.
It is very clear.
···
From: [email protected] [mailto:[email protected]] On Behalf Of Jan Wienold
Sent: lundi, 11. octobre 2010 12:23
To: Radiance general discussion
Subject: Re: [Radiance-general] Evalglare - Luminance or Illuminance
Hi Apiparn,
if you use the -i option, you need to measure the vertical illuminance and you should do that as close to the lense as possible ! In that case, evalglare will use the value provided by -i as vertical illuminance.
if you don't use the -i option and provide an image smaller than 180°, then the vertical illuminance will be less than the real value and this might have an significant influence, depending on the situation!
The detection of the glare sources and the calculation of the contribution of the glare sources to the DGP are only influenced minor when you use a smaller view angle than 180°.
In case of DGI and UGR you don't need a 180° image. Be careful when trying to evaluate these glare metrics - especially that the parameters for the detection of the glare sources fit to your scenes and that this fits also to the validity ranges of the equations! (e.g. DGI is only defined for a window as glare source and the UGR is valid only for medium sized solid angles of the artifical glare source). Always check by using -c option, if the "correct" glare sources are detected, when using other glare metric than DGP! The DGP is very robust concerning the detection parameters since the main contribution comes from the vertical eye illuminance (except you have the sun or a specular reflection of it in the field of view).
Cheers,
Jan
Borisuit Apiparn wrote:
Hi Jan,
Thanks a lot for your quick reply.
If I use the -i option (~120° -with fisheye lens), will the vertical illuminance be much different with the image of 180° view?
Moreover , for calculating DGI or UGR by Evalglare, we don't need the full 180° ?
Cheers,
Apiparn Borisuit
EPFL ENAC ICARE LESO-PB
LE 001 (Bâtiment LE)
Station 18
CH-1015 Lausanne
Téléphone +4121 69 36265<callto:+41216936265>
Fax +4121 69 32722
From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Jan Wienold
Sent: lundi, 11. octobre 2010 11:18
To: Radiance general discussion
Subject: Re: [Radiance-general] Evalglare - Luminance or Illuminance
Hi Apiparn,
the main thing is, that for the DGP the vertical illuminance at eye level is needed. Evalglare calculates this value from the given image and needs therefore the full 180°!
In case you are using a camera, which does not cover the full 180°, you can also measure the vertical illuminance and feed this illuminance value by using the -i option. In case you are using a non-fish-eye lens and evalglare is blocking another view than -vta, I could send you another version until the next release will be put online. Within the next release, all view types will be allowed.
Cheers,
Jan
Borisuit Apiparn wrote:
Hi Jan,
According to your previous reply about the needed view (180° fisheye -vta) for EVALGLARE, why can't we use 120° to 140°, due to the human field of view?
Sorry if it is a redundant question. I 'm just new in the list.
Cheers,
Apiparn
Jan wrote:
Hi Andrew,
yes, evalglare needs a 180° fish-eye(-vta)- LUMINANCE image. Internally
it calculates the vertical illuminance as Greg mentioned before.
A value of 0.4756 is a rather high value (-> 48% are disturbed by glare).
At the last building simulation conference, I suggested some "glare
classes" based on user assessments, which may help to interpret the DGP
values.
(table 5 in http://www.ibpsa.org/proceedings/BS2009/BS09_0944_951.pdf ).
Further details can be found also in my dissertation "Daylight Glare in
Offices", which will be available in some days as pdf on our web-site.
Cheers,
Jan
________________________________
_______________________________________________
Radiance-general mailing list
[email protected]<mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general
--
Dr.-Ing. Jan Wienold
Project Manager
Fraunhofer-Institut für Solare Energiesysteme
Thermal Systems and Buildings, Lighting and Daylighting
Heidenhofstr. 2, 79110 Freiburg, Germany
Phone: +49(0)761 4588 5133 Fax:+49(0)761 4588 9133
[email protected]<mailto:[email protected]>
In office:
Mo,Tue: 8:30-18:00
We,Thu: 8:30-16:00
Fr: 8:30-15:30
________________________________
_______________________________________________
Radiance-general mailing list
[email protected]<mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general
--
Dr.-Ing. Jan Wienold
Project Manager
Fraunhofer-Institut für Solare Energiesysteme
Thermal Systems and Buildings, Lighting and Daylighting
Heidenhofstr. 2, 79110 Freiburg, Germany
Phone: +49(0)761 4588 5133 Fax:+49(0)761 4588 9133
[email protected]<mailto:[email protected]>
In office:
Mo,Tue: 8:30-18:00
We,Thu: 8:30-16:00
Fr: 8:30-15:30