[Radiance-general] help pfilt and low values dgp
Jan Wienold
jan.wienold at epfl.ch
Wed Aug 12 09:42:49 PDT 2015
Hi Jasper and Alstan,
I just found this in the revision-logging of the evalglare source
code(it is such a long time ago that I could not remember...) :
/* evalglare.c, v1.11 2013/01/17 wienold
- fix output bug of dgp, when using -i or -I
*/
are you using an older version of evalglare than v1.11 which is from
January 2013??
best,
Jan
Am 8/11/15 um 5:33 PM schrieb J. Alstan Jakubiec:
> Hi Jasper,
>
> This is one of the tricky aspects of doing glare analysis with your
> own HDR images. A couple of pointers are below,
>
> * You will need to crop your image to a square aspect about the
> image center using the pcompos
> <http://radsite.lbl.gov/radiance/man_html/pcompos.1.html> tool.
> There was a helpful discussion on maintaining image exposure
> values while doing this here
> <http://www.radiance-online.org/pipermail/radiance-general/2011-March/007701.html>.
> * The -vv and -vh parameters are just best guesses according the HDR
> generation software. Once you have cropped the image, you will
> want to open the resulting HDR in a text editor and manually
> change the header 'VIEW' field to include -vta -vv 180 -vh 180.
> You may also specify them via the command line at this point, as
> you have done. I like to keep it associated with the image.
> * After that, unless I am forgetting something (others can chime
> in), you are ready to run evalglare. I would run it with the -d
> flag, which will report a lot of details. Most usefully, it
> reports illuminance as derived from the image, which you can
> compare to your measured Ev value to check the validity of the
> HDR. If your HDR is well-calibrated, not inputting the measured
> illuminance value should be perfectly accurate.
> * I suspect that inputting measured illuminance is somewhat broken
> in the current version of evalglare as I have the same problem
> that you do. One option is to use the -1 option to evalglare,
> which will return only a single DGP value. It seems to avoid this
> error.
> > evalglare -1 -i 2500 image.hdr
>
> By the way, to avoid some of this cropping and exposure value pain, I
> use an image-processing tool (like PIL for Python) these days that can
> maintain EXIF data while cropping the source jpeg files. Though
> perhaps the cure is worse than the disease in this case..
>
> Best,
> Alstan
>
> On 8/11/2015 11:08 PM, Jasper Overduin wrote:
>> Dear all,
>>
>> I have changed my lens to one with 180 circular view to do a contrast
>> analysis (hdrscope) and meanwhile the glare analysis in evalglare. If
>> i use the commands in evalglare getinfo i get the (HDR composed with
>> photosphere on a mac, calibrated with luminance pistol) i get a value
>> for the lens -vv and -vh which is not over 100, with a lens of 180. I
>> can imagine that the photo ratio and the lens are not the same and
>> that causes this problem. But when I enter the external measured Ev,
>> the value the dgp goes somehow to zero. The fact that the gdp is zero
>> with a maximum luminance of 5600 cd/m2 and Ev of 2500 lux makes me a
>> bit suspicious. How accurate is the result of the dgp without
>> external vertical lux? is it possible to use this value?
>>
>> hdr files and printscreens of evalglare
>> https://www.dropbox.com/sh/ei1y4d2v6hapdsr/AACgVMPd1o0EdK-0q8CFvUGga?dl=0
>>
>>
>> Greetings Jasper
>>
>>
>> *
>> *
>> *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
>>
>> On 1 May 2015 at 12:15, Jan Wienold <jan.wienold at epfl.ch
>> <mailto:jan.wienold at epfl.ch>> wrote:
>>
>> Hi Jasper,
>>
>> I briefly looked at your image - for sure you get a low DGP value
>> if your illuminance at camera (or eye) level is only about
>> 300lux... It is not the matter of the fish eye lens it is a
>> matter of your lighting condition.
>> When I remember correctly, for the experiments I did for my PhD,
>> the people adjusted the blinds in a way, that they had 2500-3000
>> lux at the eye level and they were less than 20% of them
>> dissatisfied. So a value of 300 means one order of magnitude less
>> light at the eye level and a much lower adaptation level.
>> So I definitely understand the low DGP value in that case. The
>> images themselves look reasonable, so I don't think there is a
>> problem in calibration/processing so far (at least not for these
>> low luminance levels-it might be more tricky to calibrate for the
>> high luminance values when you get stray-light from the multiple
>> lenses).
>>
>> If all your images are like that it means you have a very low
>> daylight contribution at the place you measure. I'm not sure if
>> DGP is then the right way to measure glare in that case - as I
>> wrote it is made more for the daylight oriented workplace with
>> higher levels and also to take into account very high luminances
>> (e.g. sun or specular reflections of the sun). DGP might be
>> modified in future, but these experiments are just starting.
>>
>> Jan
>>
>>
>>
>>
>>
>>
>> Am 4/30/15 um 10:41 PM schrieb Jasper Overduin:
>>>
>>> Thank you for the fast reply. We are still having some
>>> problems with the outcome of Evalglare. With an external
>>> luxometre we have done some tests now. The DGP is still very
>>> low or zero. It seems that in almost all the case the DGP is
>>> low. In literature we read that values above 20% are normal.
>>> What do you think? is the data much better if we use a full
>>> 180 degree lens?
>>>
>>> .hdr file https://www.dropbox.com/s/l10x7tri49btr8r/ff.hdr?dl=0
>>> print screen cmd
>>> https://www.dropbox.com/s/yv1lamhiirjhvxq/imp%20pan.jpg?dl=0
>>> test.pic https://www.dropbox.com/s/nspdu01477mchsz/test.pic?dl=0
>>>
>>> Greetings Jasper
>>>
>>>
>>>
>>> *
>>> *
>>> *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
>>>
>>> On 30 April 2015 at 13:55, Jan Wienold <jan.wienold at epfl.ch
>>> <mailto:jan.wienold at epfl.ch>> wrote:
>>>
>>> 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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>>>
>>>
>>>
>>>
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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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>> Radiance-general mailing list
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>> http://www.radiance-online.org/mailman/listinfo/radiance-general
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>>
>>
>>
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>
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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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