[Radiance-general] help pfilt and low values dgp

[Jan Wienold]

Hi Jasper,

why are you using -vth -vh 140 -vv 80 when in your header of the HDR 
image the view is specified as  -vtv -vh 98.797409 -vv 75.402067 ?
Manipulating the lense type is really dangerous - in that case you 
change from a perspective view to a hemispherical fish eye view, without 
changing the image!!

If I apply evalglare for your image I get 0.17 as DGP (which is still 
very low, but you have only 2000cd/m2 as maximum value, so this can be 
expected). Be aware, that DGP accounts only for glare from a high amount 
of daylight and/or spots of extreme luminances (>50000cd/m2), but not 
for contrasted glare between task (e.g. Monitor) and immediate 
surroundings for lower adaptation levels. This is subject of current 
research (also here at EPFL) and there might be an extension of the DGP 
in future, depending on the outcome of new experiments.

Back to the lens-type:
It is extremely important, that the right view type is given to 
evalglare, otherwise ALL calculated values (it doesn't matter if this is 
evalglare or findglare) are wrong. These errors could be huge, more than 
100% for calculating the illuminance out of a 180 degree image.

If you manipulate an image by pcomb, in general the view is marked as 
"invalid" in the header, because with that tool you could manipulate the 
image in a way, that the original view is not valid any more. This is 
why from evalglare version 1.0 on a check on the header was included, 
because many people were creating wrong headers without knowing it and 
then evalglare was calculating wrong values, when the header was invalid.

In addition for calculating the DGP it is important to have the 
illuminance at camera level. evalglare calculates this value out of the 
image. But if the image does not cover 180 degree, then the calculated 
value for the illuminance is too low. For that reason, the -i option was 
included, so you can provide the illuminance to evalglare (when you 
measure it with an illuminance sensor).

So in your case, you should measure the illuminance just besides the lens.
Then (in case this is the right lens description) you should use
evalglare -i LUXVALUE -vtv -vh 98.797409 -vv 75.402067 IMAGE_NAME
or better, if your task is always at the same place:
evalglare -i LUXVALUE -vtv -vh 98.797409 -vv 75.402067  -T 395 230 .6 -c 
CHECK_FILE_PICTURE IMAGE_NAME

good luck!

Jan



Am 4/30/15 um 6:04 PM schrieb Jasper Overduin:
> Somehow cant use the command pfilt or change the pcomb, does this has 
> to do with the program Radiance? I have installed the version of 
> windows from the site, with evalglare v1.11windows . The problem is 
> that I have composed a .hdr (out of 7 jpg on a mac) and after using 
> the command c:/HDRI>evalglare -vth -vh 140 -vv 80 image.hdr all the 
> dgp results are really low, less than 5%. The problem can be in the 
> .hdr (calibrated as well) or is in the way evalglare is not working as 
> it shoot on my computer.
>
>
> *.hdr file* (post-it is calibration point 167,98) 
> https://www.dropbox.com/s/4z69y358yt8ii4z/1_sv_am.hdr?dl=0
> *images* original 
> https://www.dropbox.com/sh/adyyxjkv6eykyek/AAC96QUTpLh_Ef2U8Mppki8ta?dl=0
> *command printscreen* 
> https://www.dropbox.com/s/0pbn105p0z0iinu/Imp%20pan.jpg?dl=0
>
>
> Need the help!
>
> Greetings Jacobus
>
> *
> *
> *Jasper Overduin*
> MSc Building Technology graduate student at Delft University of 
> Technology*
> *
>
> *S* Groenhoevelaan 3
> *P*2343 BP Oegstgeest
> *T* +31 6 15 64 48 56 (NL)
> *T* +56 9 51 11 76 48 (CL)
> *E *overduin.jasper at gmail.com <mailto:overduin.jasper at gmail.com>
> *Skype *jasper.overduin
>
>
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-- 
Dr.-Ing.  Jan Wienold
Ecole Polytechnique Fédérale de Lausanne (EPFL)
EPFL ENAC IA LIPID

http://people.epfl.ch/jan.wienold
LE 1 111 (Office)
Phone    +41 21 69 30849

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