[Radiance-general] Faulty fisheye HDR, DGP always 1.0

[Greg Ward]

Ha.  Jan is right -- the HDR values are way off.  I should have looked at the result more closely and noticed that everything was too bright.

I can take your JPEGs and give them to Photosphere or hdrgen, combining them using a generic response function.  I cannot solve for the camera response with these inputs, which likely means that the camera is playing around with the tone curve on the different exposures.  This is a no-no, and indicates that the camera is probably not suitable for HDR capture.  Nevertheless, hdrgen can create something usable that does not agree at all with your result.

By the way, your shortest exposure is still clipping the sun, which means that your DGP won't be accurate for this scene, even if you can get your HDR builder to work unless you can get a shorter exposure.

Cheers,
-Greg

> From: Jan Wienold <jan.wienold at epfl.ch>
> Date: February 6, 2018 9:24:54 AM PST
> was it taken on mercury ? ;-)
> the luminances are far off... it sums up to more than 600000 lux 
> Jan 
> 
> 
> On 06.02.18 18:18, Greg Ward wrote:
>> Hi Raghu,
>> 
>> We may need to wait to hear from Jan or someone who understands evalglare better than I do.  I don't think there is a problem with your HDR image as you generated it.
>> 
>> -Greg
>> 
>>> From: raghuram kalyanam <kalyanam at rhrk.uni-kl.de>
>>> Date: February 6, 2018 9:05:41 AM PST
>>> 
>>> Hi Greg,
>>> 
>>> I added these options while passing to evalglare like below.
>>> 
>>> evalglare -vta -vh 180 -vv 180 <hdr file>, and it worked but it always gives 1.0 as DGP (even other parameters are out of bounds).
>>> 
>>> With out those options evalglare throws an error.
>>> 
>>> Apart from that
>>> 
>>> Are all the LDR’s provided, valid to combine into HDR?
>>> 
>>> I doubt if one or more of the LDR’s is the culprit (especially something to do with over or under exposure).
>>> 
>>> Best Regards,
>>> Raghu
>>> 
>>>> On Feb 6, 2018, at 5:05 PM, Greg Ward <gregoryjward at gmail.com> wrote:
>>>> 
>>>> Hi Raghu,
>>>> 
>>>> It looks like your HDR image header is missing the necessary view information.  Typically, this might be something like:
>>>> 
>>>> VIEW= -vta -vh 180 -vv 180
>>>> 
>>>> for a perspective such as yours.  You should be sure that your fisheye mapping corresponds to one of the standard Radiance types.
>>>> 
>>>> Best,
>>>> -Greg
>>>> 
>>>>> From: raghuram kalyanam <kalyanam at rhrk.uni-kl.de>
>>>>> Date: February 6, 2018 5:21:59 AM PST
>>>>> 
>>>>> Hi All,
>>>>> 
>>>>> I am trying to asses visual discomfort  using fisheye HDR images. We generated HDR image from a set of 360 degree LDRs and then converted to fisheye HDR ( using a custom made tools). The intension was to use these Fisheye HDRs as input to Evalglare and get DGP value. The Camera used is Ricoh Theta V 360 degree camera.
>>>>> 
>>>>> The problem I am facing is, the DGP calculated from the generated fisheye HDR with Evalglare is always 1.0. We did the calibration but I would like to have expert opinion from you people, what is going wrong with these set of images. Here is the link to the pictures.
>>>>> 
>>>>> It would be great if anyone could identify the issue.
>>>>> 
>>>>> Best Regards,
>>>>> Raghu
>>> 
>> 
>> 
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> 
> -- 
> Dr.-Ing.  Jan Wienold
> Ecole Polytechnique Fédérale de Lausanne (EPFL)
> EPFL ENAC IA LIPID
> 
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