Thanks for the heads up!
I'm in the process of choosing a camera and the Digital Rebel seems to be a fine choice indeed. However I would like some more background info on the file formats. I can't seem to be able to dig up much on what the "raw" format actually contains, I imagine it isn't necessarily the same from camera to camera? Are there parameters to be passed on to the hdr generating software based on the raw format?
I have no support for macosx, so it's between windows and linux, although the hdrgen program looks interesting as it's command line based and easier to enter into batch processing. But I couldn't find any documentation about it and the executable doesn't have any built in help whatsoever. 
Could I possibly ask you to roughly describe the process of generating hdr images from those taken with the Rebel? Any calibration involved?
Barbara
Barbara Matusiak wrote:
I wonder if it is possible to convert pictures taken by digital camera to Radiance format? And if yes, how it could be done? The Radiance format enables reading of luminance values directly from the pictures, something that could be very usefull in the project I plan to start soon.
Yes, but only if you shoot the images in a specific manner and convert them to high dynamic range (HDR) format first. A single image does not contain the dynamic range necessary for what you want to do. But for typical scenes, if you simply bracket your exposure (using aperture, not changing shutter speed) by two F stops in each direction, you can use utilities like Debevec's HDR Shop or Greg Ward's Photosphere (or his command-line hdrgen) to merge those into an HDR image with the full dynamic range. You can then use Radiance tools like falsecolor (and even pcond) to extract real luminance information from a photograph.
We use a Canon Digital Rebel here in my office to create these image sequences. The autobracket function of the camera is very useful for this. Many "prosumer" cameras have this feature, but you must make sure the camera will separate the images by two f-stops. Of course you can do it manually too, but then you usually need a tripod to keep everything in registration. You also need to "go manual" to capture scenes of really high dynamic range, using more images to capture the full range.
I've been meaning to place some samples on my website, but haven't had time. But these resources are better anyway:
http://www.anyhere.com/
http://www.debevec.org/HDRShop/HDR photography is extremely cool. You can even use HDR images as light sources for Radiance scenes! Santiago Torres of this list has done quite a bit of work in that. Search the radiance-general archives for details. Have fun!
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Rob Guglielmetti
e. [email protected]
w. www.rumblestrip.org_______________________________________________
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associate professor Barbara Matusiak Tel.: +47 73 59 50 77
Faculty of Arcitecture and Fine Art Fax: +47 73 59 53 88
Norwegian Univ. of Science and Technology (NTNU) [email protected]
N-7491 Trondheim, Norway http://www.ab.ntnu.no/byggekunst/ansatte/ansattesider/bam.html
ยทยทยท
At 10:38 28.05.2004 -0400, you wrote: