[Radiance-general] help pfilt and low values dgp
Jan Wienold
jan.wienold at epfl.ch
Wed Aug 12 02:39:41 PDT 2015
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
>>
>>
>> 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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>>
>> --
>> 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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--
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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