[Radiance-general] help pfilt and low values dgp

Wed Aug 12 06:21:53 PDT 2015

Im using evalglare 1.10 release 30.09.2012 with windows 7
The photos are calibrated with a (il)lumination pistol with 4 different
measurements (with maximum deviation of 0.4 cd/m2)
There is a certain coating on the window, not sure what kind. but as you
said the difference is huge.

Within the program of HDRscope there is a similar function and gives and
errer as well if i use an external Ev value.

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
*Skype *jasper.overduin

On 12 August 2015 at 06:39, Jan Wienold <jan.wienold at epfl.ch> wrote:

> Hi Jasper,
> hi Alstan,
>
> I guess there are several issues in that case. First of all, as Alstan
> wrote, you should crop the image and provide the correct lens specification
> to evalglare. Be aware that editing the header could be dangerous, because
> sometimes editors add strange characters or you don't see tabs in the
> header with marks the view string there as "invalid" . In case the header
> is interpreted "wrong" in evalglare, the results could be really random and
> could differ for more than 100% from the right ones (e.g. the calculation
> of the vertical illuminance, see presentation on the Radiance workshop in
> 2012). The header treatment is much more robust since the evalglare version
> 1.08, but still the user should take care of providing a correct header.
> evalglare is relying on a correct radiance header. To be on the safe side,
> you should always use the command option to provide the correct view option
> to evalglare.
> Also you should make sure, that you use a view type which really
> corresponds to your lens. If your real lens is a hemispherical fish eye and
> you provide  -vta as view string, the angles and solid angles are
> calculated wrong in evalglare and you get wrong results. So make sure that
> you use -vta only if your lens is a angular fish eye.
> And please don't use the -1 option in evalglare!!! This is a special
> (undocumented) option to get fast results on images calculated without
> ambient calculations. If you use it for normal images, the glare sources
> might not detected correctly and you could get big differences. It is
> working mostly properly in images with large black areas (-ab 0).
> Since the -1 option is not robust for normal images, this option is
> undocumented. There exist also other undocumented options since 2009 for
> hdr treatment(e.g. pixel overflow correction, image fillup when ccd-array
> is smaller than the projected image...), but these options are by purpose
> undocumented because they should be used only in special cases and can
> cause wrong results when not used properly.
>
> If I look at your image, I guess your calibration is not correct. The sun
> has a luminance of 2e10 cd/m2. In case of low transmittance glazing you
> still have a luminance of  Xe9 cd/m2, lets say at least 1e9cd/m2, which is
> factor 200000 higher than you measured!!! And be aware you you might have
> to deal with blooming  effects when you have a pixel overflow (especially
> when looking into the sun). Not sure about your camera setting, but if you
> still have an overflow for the shortest exposure, you should think of
> adding a neutral grey filter to reduce the overall transmittance to the ccd.
>
> Finally I can't reproduce the 0 output of evalglare. I used your image and
> used as well the 2500lux as input (even if the image is not cropped
> correctly and the view string is wrong). See here:
> *evalglare -i 2500 pmar_sin_03.hdr*
> *Notice: Low brightness scene. Vertical illuminance less than 380 lux! dgp
> might underestimate glare sources*
> *dgp,dgi,ugr,vcp,cgi,Lveil: 0.311778 18.132195 21.670120 44.798004
> 27.925421 58.052605  *
>
> But I always get an non-0 result, I never experienced this before. I tried
> the linux ,the mac and also the windows version with your image - it didn't
> happen. So which version are you using? Which operating system? (type
> evalglare -v to find out)
>
> @Alstan: Can you provide me another example where this happens as well?
> Which version are you using? Which operating system?
>
> A zero value should never appear, except your image is completely black.
>
> 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>
> 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>overduin.jasper at gmail.com
> *Skype *jasper.overduin
>
> On 1 May 2015 at 12:15, Jan Wienold <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>
>> 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>overduin.jasper at gmail.com
>>> *Skype *jasper.overduin
>>>
>>> On 30 April 2015 at 13:55, Jan Wienold < <jan.wienold at epfl.ch>
>>> 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>
>>>> https://www.dropbox.com/s/4z69y358yt8ii4z/1_sv_am.hdr?dl=0
>>>> *images* original
>>>> <https://www.dropbox.com/sh/adyyxjkv6eykyek/AAC96QUTpLh_Ef2U8Mppki8ta?dl=0>
>>>> https://www.dropbox.com/sh/adyyxjkv6eykyek/AAC96QUTpLh_Ef2U8Mppki8ta?dl=0
>>>> *command printscreen*
>>>> <https://www.dropbox.com/s/0pbn105p0z0iinu/Imp%20pan.jpg?dl=0>
>>>> 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>overduin.jasper at gmail.com
>>>> *Skype *jasper.overduin
>>>>
>>>>
>>>> _______________________________________________
>>>> Radiance-general mailing listRadiance-general at radiance-online.orghttp://www.radiance-online.org/mailman/listinfo/radiance-general
>>>>
>>>>
>>>> --
>>>> 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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>>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>>
>>>>
>>>
>>
>>
>> _______________________________________________
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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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>> http://www.radiance-online.org/mailman/listinfo/radiance-general
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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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