Hi Clarence, I think it is common to have better success with fewer images instead of a full 15-image sequence. Having extra frames is probably good practice since you might not get another chance to capture that scene, but you shouldn't need that many for the actual HDR creation. You mentioned trying images 6, 9, 10, and 11 as example. The important thing would be to select images that capture as much of the low, middle, and high exposure range as possible - particularly important for a new camera response function. Let's say your image exposures are in order from darkest to brightest. Your selected sequence should hopefully include at least one of the first few under-exposed images - or whichever one is dark enough to have some information but no fully white pixels. You should also include at least one of the last few over-exposed images - hopefully one with image information but no fully black pixels. Then pick a few of the exposures in between. You might find better success with four or five images instead of 15.
You might also try changing some other settings regarding automatic alignment, ghost removal, lens flare removal, etc. if these or any other default settings might adversely affect your specific image sequence. -Chris From: Clarence Wang [mailto:[email protected]] Sent: Monday, October 29, 2018 10:32 PM To: High Dynamic Range Imaging <[email protected]> Subject: [External] [HDRI] hdrgen problems Hi Greg, I've subscribed the HDRI mailing list and the request seemed to be approved. For the questions mentioned before, I got failure to derive the camera response function when running a whole set of images (1-13) in Photosphere. Thus, I just selected 9 images in sequence (1-9) for rendering HDR image. However, it was confusing that I still failed to derive the camera response function using the other sequence of images (3-11) which was successfully run using 'hdrgen' tool and was to generate a new camera response function (the second-order polynomial). Since you mentioned "even the same set of images given twice won't necessarily yield the same coefficients, although they should be close", which function or rendered HDR image is reliable? Or, can we trust the HDR image rendered with different polynomials but well agree with each other (almost overlap)? Also, If both Photosphere and hdrgen tool cannot solve response function and fail to render a HDR image using a sequence of 15 exposed images, is it reasonable to select less number of images (say, 6, 9, 10, 11) to yield the HDR image and relevant camera response function using Photosphere or hdrgen tool ? Thanks, Clarence ____________________________________________________________ Electronic mail messages entering and leaving Arup business systems are scanned for viruses and acceptability of content.
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