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Today's Topics:
1. Convert equisolidangular to equiangular projection (Zhe Kong)
2. Re: Convert equisolidangular to equiangular projection
(Gregory J. Ward)
3. Re: Convert equisolidangular to equiangular projection
(J. Alstan Jakubiec)
4. Re: Convert equisolidangular to equiangular projection
(Claus Br?ndgaard Madsen)
----------------------------------------------------------------------
Message: 1
Date: Wed, 25 Jan 2017 15:15:49 -0600
From: Zhe Kong <[email protected]>
To: [email protected]
Subject: [HDRI] Convert equisolidangular to equiangular projection
Message-ID:
<CAEV5NycbY6hLjbPSmVb1H5pj_PW-Y4rNMjzrY4KJ2sLXkbV_wA@mail.
gmail.com>
Content-Type: text/plain; charset="utf-8"
Dear list:
I am trying to compare HDR images and simulated luminance maps. Since I use
SIGMA 8mm 1:3.5 for Canon, I need to convert equisolid-angular to
equiangular project. I see very useful information from the post below:
https://www.radiance-online.org:447/pipermail/radiance-
general/2015-August/011184.html
However, I still have some questions need to figure out.
1) pinterp does not include equisolid-angular projection, so a equation
needs to be applied to the function. Greg mentioned this simple expression,
sin(theta)/theta, but I am still confused. Could anyone offer me the
command?
2) The post discussed the steps of processing HDR images. If I get it
right, the steps following "adjust exposure" are vignetting correction,
adding view information, converting project from equisolidangular to
equiangular, then calibrating the image. I use a GOSSEN Starlite 2 to
record the luminance value on a grey card for calibration. My question is,
should I calibrate the image before or after converting fisheye projection?
Any suggestions or explanation would be appreciated.
Zhe
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Message: 2
Date: Wed, 25 Jan 2017 16:48:55 -0800
From: "Gregory J. Ward" <[email protected]>
To: High Dynamic Range Imaging <[email protected]>
Subject: Re: [HDRI] Convert equisolidangular to equiangular projection
Message-ID: <[email protected]>
Content-Type: text/plain; charset=iso-8859-1
Hi Zhe,
You should be able to apply the fisheye_corr.cal file I gave you earlier
to correct the distortion and make it an angular fisheye image that pinterp
works with. (Why you need pinterp, I am not sure.) The command is as
suggested in the fisheye_corr.cal file itself:
pcomb -f fisheye_corr.cal -o fisheye.hdr \
> getinfo -a "VIEW= -vta -vh 180 -vv 180" \
> corrected.hdr
This will also crop the area outside of 180? to black, assuming that is
what you want. It assumes that you have already cropped the image to a
minimum square area. You should apply vignetting correction and absolute
calibration first.
Cheers,
-Greg
> From: Zhe Kong <[email protected]>
> Date: January 25, 2017 1:15:49 PM PST
>
> Dear list:
> I am trying to compare HDR images and simulated luminance maps. Since I
use SIGMA 8mm 1:3.5 for Canon, I need to convert equisolid-angular to
equiangular project. I see very useful information from the post below:
>
> https://www.radiance-online.org:447/pipermail/radiance-
general/2015-August/011184.html
>
> However, I still have some questions need to figure out.
> 1) pinterp does not include equisolid-angular projection, so a equation
needs to be applied to the function. Greg mentioned this simple expression,
sin(theta)/theta, but I am still confused. Could anyone offer me the
command?
>
> 2) The post discussed the steps of processing HDR images. If I get it
right, the steps following "adjust exposure" are vignetting correction,
adding view information, converting project from equisolidangular to
equiangular, then calibrating the image. I use a GOSSEN Starlite 2 to
record the luminance value on a grey card for calibration. My question is,
should I calibrate the image before or after converting fisheye projection?
>
> Any suggestions or explanation would be appreciated.
> Zhe
>
------------------------------
Message: 3
Date: Thu, 26 Jan 2017 13:57:36 +0800
From: "J. Alstan Jakubiec" <[email protected]>
To: [email protected]
Subject: Re: [HDRI] Convert equisolidangular to equiangular projection
Message-ID: <[email protected]>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"
Hi Zhe,
As far as I am aware, the Sigma 8mm f/3.5 is an equi-angular (-vta)
lens, and the Sigma 4.5mm f/2.8 is an equi-solid angle (-???) lens. I am
having trouble finding a source from Sigma right now, but Cauwerts,
Bodart and Deneyer's paper
<http://www.tandfonline.com/doi/abs/10.1582/LEUKOS.2012.08.03.002> says
so.
That said, if you do end up with an equi-solidangle image, I have a
python script that converts equi-solid angle to equi-angle for each
source jpeg while maintaining the EXIF data. I used this to convert
equi-solidangle images from my Canon 8-15mm fisheye lenses.
Best,
Alstan
On 1/26/2017 8:48 AM, Gregory J. Ward wrote:
> Hi Zhe,
>
> You should be able to apply the fisheye_corr.cal file I gave you earlier
to correct the distortion and make it an angular fisheye image that pinterp
works with. (Why you need pinterp, I am not sure.) The command is as
suggested in the fisheye_corr.cal file itself:
>
> pcomb -f fisheye_corr.cal -o fisheye.hdr \
> > getinfo -a "VIEW= -vta -vh 180 -vv 180" \
> > corrected.hdr
>
> This will also crop the area outside of 180? to black, assuming that is
what you want. It assumes that you have already cropped the image to a
minimum square area. You should apply vignetting correction and absolute
calibration first.
>
> Cheers,
> -Greg
>
>> From: Zhe Kong <[email protected]>
>> Date: January 25, 2017 1:15:49 PM PST
>>
>> Dear list:
>> I am trying to compare HDR images and simulated luminance maps. Since I
use SIGMA 8mm 1:3.5 for Canon, I need to convert equisolid-angular to
equiangular project. I see very useful information from the post below:
>>
>> https://www.radiance-online.org:447/pipermail/radiance-
general/2015-August/011184.html
>>
>> However, I still have some questions need to figure out.
>> 1) pinterp does not include equisolid-angular projection, so a equation
needs to be applied to the function. Greg mentioned this simple expression,
sin(theta)/theta, but I am still confused. Could anyone offer me the
command?
>>
>> 2) The post discussed the steps of processing HDR images. If I get it
right, the steps following "adjust exposure" are vignetting correction,
adding view information, converting project from equisolidangular to
equiangular, then calibrating the image. I use a GOSSEN Starlite 2 to
record the luminance value on a grey card for calibration. My question is,
should I calibrate the image before or after converting fisheye projection?
>>
>> Any suggestions or explanation would be appreciated.
>> Zhe
>>
> _______________________________________________
> HDRI mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/hdri
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Message: 4
Date: Thu, 26 Jan 2017 10:17:01 +0000
From: Claus Br?ndgaard Madsen <[email protected]>
To: High Dynamic Range Imaging <[email protected]>
Subject: Re: [HDRI] Convert equisolidangular to equiangular projection
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
If it is of any interest I did this overview some years back concerning
various projections
[cid:[email protected]]
Claus B. Madsen
Assoc. Prof., Ph.D. | Department of Architecture and Media Technology
Phone: +45 9940 8788 | E-mail: [email protected]<mailto:[email protected]>
Aalborg University | Rendsburggade 14 | 9000 Aalborg | Denmark
Employee No.: 107255 | Vat No.: DK29102384
From: "J. Alstan Jakubiec" <[email protected]>
Reply-To: High Dynamic Range Imaging <[email protected]>
Date: Thursday, 26 January 2017 at 06.57
To: "[email protected]" <[email protected]>
Subject: Re: [HDRI] Convert equisolidangular to equiangular projection
Hi Zhe,
As far as I am aware, the Sigma 8mm f/3.5 is an equi-angular (-vta) lens,
and the Sigma 4.5mm f/2.8 is an equi-solid angle (-???) lens. I am having
trouble finding a source from Sigma right now, but Cauwerts, Bodart and
Deneyer's paper<http://www.tandfonline.com/doi/abs/10.1582/LEUKOS\.
2012.08.03.002> says so.
That said, if you do end up with an equi-solidangle image, I have a python
script that converts equi-solid angle to equi-angle for each source jpeg
while maintaining the EXIF data. I used this to convert equi-solidangle
images from my Canon 8-15mm fisheye lenses.
Best,
Alstan
On 1/26/2017 8:48 AM, Gregory J. Ward wrote:
Hi Zhe,
You should be able to apply the fisheye_corr.cal file I gave you earlier
to correct the distortion and make it an angular fisheye image that pinterp
works with. (Why you need pinterp, I am not sure.) The command is as
suggested in the fisheye_corr.cal file itself:
pcomb -f fisheye_corr.cal -o fisheye.hdr \
> getinfo -a "VIEW= -vta -vh 180 -vv 180" \
> corrected.hdr
This will also crop the area outside of 180? to black, assuming that is
what you want. It assumes that you have already cropped the image to a
minimum square area. You should apply vignetting correction and absolute
calibration first.
Cheers,
-Greg
From: Zhe Kong <[email protected]><mailto:[email protected]>
Date: January 25, 2017 1:15:49 PM PST
Dear list:
I am trying to compare HDR images and simulated luminance maps. Since I
use SIGMA 8mm 1:3.5 for Canon, I need to convert equisolid-angular to
equiangular project. I see very useful information from the post below:
https://www.radiance-online.org:447/pipermail/radiance-
general/2015-August/011184.html
However, I still have some questions need to figure out.
1) pinterp does not include equisolid-angular projection, so a equation
needs to be applied to the function. Greg mentioned this simple expression,
sin(theta)/theta, but I am still confused. Could anyone offer me the
command?
2) The post discussed the steps of processing HDR images. If I get it
right, the steps following "adjust exposure" are vignetting correction,
adding view information, converting project from equisolidangular to
equiangular, then calibrating the image. I use a GOSSEN Starlite 2 to
record the luminance value on a grey card for calibration. My question is,
should I calibrate the image before or after converting fisheye projection?
Any suggestions or explanation would be appreciated.
Zhe
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