Greg, Thanks - that makes sense. I just checked and the relative proportions of the Firefly HDR are substantially different than the relative proportions of the Canon HDR - bummer. Looks like I will need to figure out a way to calculate ISO to input into the header. What does Photosphere need in the EXIF header for best accuracy?
(Make and model) Shutter speed F stop ISO Anything else? Kevin Van Den Wymelenberg Integrated Design Lab Boise, Director College of Art & Architecture, Assistant Professor University of Idaho Boise Center www.uidaho.edu/idl ph. 208.724.9456 fx. 208.343.0001 306 S. 6th Street Boise, ID 83702 From: "Gregory J. Ward" <[email protected]> Reply-To: High Dynamic Range Imaging <[email protected]> Date: Fri, 17 Jun 2011 15:41:26 -0700 To: High Dynamic Range Imaging <[email protected]> Subject: Re: [HDRI] Accuracy issue from Firefly MV in Photosphere If your relative proportions are accurate, that means Photosphere is doing a good job of solving for the system response. However, there's no way for it to solve for the absolute calibration. It just uses a value that is approximate based on ISO, which it sounds like you don't know. Select a region you've measured and use the "Apply" button to calibrate against your measured luminance. Use the dialog option to save this factor for your camera and you should be good from then on. (You'll need to be consistent about the camera make, model, and version in your added Exif header, though.) -Greg > From: Kevin Van Den Wymelenberg <[email protected]> > Date: June 17, 2011 2:55:00 PM PDT > > Greg, > > Thanks for the reply. My errors are in absolute terms. I have a Minolta luminance meter and a Macbeth grey card in the middle of the scene. I am also doing comparisons of absolute luminance values produced by the FireFly as compared to the luminance results from my Canon camera on images captured at the same time of the same scene. I have high confidence in my Canon results from previous validations. The HDR that Photosphere resolves for the Firefly at first look reasonable within the scene it has logical variation in luminance values. It is the absolute errors that I am worried about. > > Thanks! _______________________________________________ HDRI mailing list [email protected] http://www.radiance-online.org/mailman/listinfo/hdri
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