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! 


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 13:44:13 -0700
To: High Dynamic Range Imaging <[email protected]>
Subject: Re: [HDRI] Accuracy issue from Firefly MV in Photosphere

Hi Kevin,

Are you errors in absolute terms or relative (e.g., one patch to another on
a Macbeth chart or similar)?

-Greg

> 
> From: Kevin Van Den Wymelenberg <[email protected]>
> 
> Date: June 17, 2011 1:19:17 PM PDT
> 
> 
> All,
> 
> I have been creating HDR images for purposes of pixel-based luminance analysis
> from photographs captured with a PointGrey Firefly MV [FMVU-13S2C (Color)].
> 
> http://www.ptgrey.com/products/fireflymv/fireflymv_usb_firewire_cmos_camera.as
> p 
> 
> It is a board level camera with usb 2 connection, uses the Sony IMX035LQR-C
> cmos sensor and a rolling shutter.  I have fixed exposure to 1, brightness to
> 0, gain to 0, and turned the frame rate off.  I have then run multiple
> exposures (10-12) using shutter speeds from 1ms to 8000ms excluding completely
> saturated exposures.   I have a fisheye lens attached but have not been able
> to run vignetting correction yet since I do not trust my response curve. I
> have been running accuracy comparisons to my Canon which I trust with poor
> comparisons.  It is successfully resolving in Photosphere, but only after I
> manually write the EXIF header since the camera actually does not write an
> EXIF header.   I have written camera make, model, f stop, and shutter into
> header.
> 
> Any ideas?
> 
> I would be happy to ftp exposures etc if it would help.
> 
> Thanks for any help!


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