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
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