[Radiance-general] Obtaining proper luminance values in scene image generated using HDR sky-probe luminance data

[Greg Ward]

Actually, you want to use:

ra_xyze -r -o orig.hdr | pcompos ...

-Greg

On Nov 23, 2012, at 6:18 PM, Mehlika Inanici <inanici at u.washington.edu> wrote:

> 
> 
> Kyle,
> 
> You can set the exposure to 1 (pfilt)  to prevent the problems you are experiencing with the probe.
> 
> 
> Mehlika
> 
> On Fri, 23 Nov 2012, Kyle Konis wrote:
> 
>> Dear list,
>> 
>> I am exploring image-based lighting in Radiance and have encountered
>> several issues with the luminance values in the scene images i am
>> generating. I am starting with a hemispherical fisheye image of the
>> sky which must be cropped to a square format via pcompos.
>> 
>> This process leads to a header which puts the EXPOSURE=5.953331e-03 in
>> a location which creates a problem in that the pixel values, as viewed
>> in Photosphere or when rendered via rpict to a test image (looking up
>> from the origin at the sky), are much lower than the original HDR
>> image.
>> 
>> #?RADIANCE
>> CAPDATE= 2012:10:21 17:05:24
>> GMT= 2012:10:22 00:05:24
>> 20111019_cloudy/201110191248.hdr:
>>       CAMERA= Canon Canon PowerShot A570 IS version v.0
>>       EXPOSURE=5.953331e-03
>>       VIEW= -vtv -vh 52.456387 -vv 40.558973
>>       CAPDATE= 2011:10:19 12:48:08
>>       hdrgen created HDR image from 'IMG_0685.JPG' 'IMG_0684.JPG'
>> 'IMG_0683.JPG' 'IMG_0682.JPG' 'IMG_0681.JPG'
>>       PRIMARIES= 0.6400 0.3300 0.3000 0.6000 0.1500 0.0600 0.3127 0.3290
>> pcompos -x 1280 -y 1280 20111019_cloudy/201110191248.hdr -340 -100
>> pfilt -1 -x 600 -y 600
>> pflip -v -c
>> pflip -h -c
>> FORMAT=32-bit_rle_rgbe