Hi Magali,
Sigma just released a 4.5 mm 180 degree fisheye for APS-C size (the smaller sensors) digital SLR cameras.
http://www.sigmaphoto.com/news/news.asp?nID=3377
I just received one yesterday from B+H photo in New York and so far it seems to deliver as promised. I'm using it with a Nikon D50.
Question (sorry if this is back to basics but despite many archive searches I'm still at a loss):
When viewing an HDR image with "ximage" and taking spot measurements with the "L" command I get reasonably accurate luminance values. When I map the HDR image as an emissive glow on to a "source" geometry and view the scene with "rvu" I get much lower luminance values than at the same spots measured in ximage. Below is the scene description:
···
########
void colorpict skypict
11 red green blue sky.hdr fisheye.cal fish_u fish_v -rz 180 -rx -90
0
skypict glow skyglow
0
4 1 1 1 0
skyglow source sky
0
4 0 0 1 180
#########
My end goal is to document various sky conditions to be used for IBL scenes.
Happy New Year and thanks in advance.
Chris
Hi Magali,
Sigma just released a 4.5 mm 180 degree fisheye for APS-C size (the smaller sensors) digital SLR cameras.
http://www.sigmaphoto.com/news/news.asp?nID=3377
I just received one yesterday from B+H photo in New York and so far it seems to deliver as promised. I'm using it with a Nikon D50.
Question (sorry if this is back to basics but despite many archive searches I'm still at a loss):
When viewing an HDR image with "ximage" and taking spot measurements with the "L" command I get reasonably accurate luminance values. When I map the HDR image as an emissive glow on to a "source" geometry and view the scene with "rvu" I get much lower luminance values than at the same spots measured in ximage. Below is the scene description:
···
########
void colorpict skypict
11 red green blue sky.hdr fisheye.cal fish_u fish_v -rz 180 -rx -90
0
skypict glow skyglow
0
4 1 1 1 0
skyglow source sky
0
4 0 0 1 180
#########
My end goal is to document various sky conditions to be used for IBL scenes.
Happy New Year and thanks in advance.
Chris
Hi Chris,
This is more of a Radiance question, I suppose, but the problem is that you have an EXPOSURE= value in your header that ximage is smart about, but the renderer ignores. To get absolute values out of rvu, either set a factor in your glow to 1/EXPOSURE (in all three channels) or "undo" the exposure by passing your picture through pfilt with -e set to the reciprocal of the exposure getinfo tells you.
Cheers,
-Greg
P.S. Having the renderers ignore the EXPOSURE line was a design decision to facilitate texture normalization under the more typical circumstance when it is being used to modify reflectance.
···
From: "[email protected]" <[email protected]>
Date: January 23, 2008 2:18:27 PM PST
Question (sorry if this is back to basics but despite many archive searches I'm still at a loss):
When viewing an HDR image with "ximage" and taking spot measurements with the "L" command I get reasonably accurate luminance values. When I map the HDR image as an emissive glow on to a "source" geometry and view the scene with "rvu" I get much lower luminance values than at the same spots measured in ximage. Below is the scene description:
########
void colorpict skypict
11 red green blue sky.hdr fisheye.cal fish_u fish_v -rz 180 -rx -90
0
skypict glow skyglow
0
4 1 1 1 0
skyglow source sky
0
4 0 0 1 180
#########
My end goal is to document various sky conditions to be used for IBL scenes.
Happy New Year and thanks in advance.
Chris