Hi Belal,
On 10/03/2017 12:12 AM, Belal Abboushi wrote:
Hi,
Thank you Clotilde and Jan. The ra_xyze command solved the problem. I
am actually using a fish eye lens (the -vh 49.0537 -vv 49.0537 was in
the original image created by hdrgen) but I am passing view info in
the evalglare line). I have few follow up questions to make sure I
understand what you mentioned regarding view type.
1. Assuming I have an angular projection, I converted that to
hemispherical projection using pinterp, and used that for Ev
calculations and absolute calibration, and then for evalglare. My
question is: Is a hemispherical projection a requirement for
calculating vertical illuminance in Radiance? If yes, should I convert
back to angular after calculating Ev
I dont understand, why you need a vth. with every re-projection you add
an additional error to your measurement. in that case it is not
necessary. evalglare can use vta for all calculations, also for the
vertical illuminance. (command: evalglare -V image).
2. Is there a way to tell if projection is Angular or hemispherical by
looking at images? I am using a low-cost Opteka 0.2x fish eye..
there's no mention by manufacturer on projection type.
then you should measure it. make marks every 5 or 10 degree on a target
(e.g. a corner of a room), covering the total field of view. If you have
an angular lens, then the pixel distance between the marks is the same.
If not, then it is at least not an angular projection. Actually a
hemispherical lens is rather rare on the market. More common is
equid-solid-angle.
Jan
Thank you for your help,
Belal
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