Hi people, I've been tinkering with hugin for a long time now and I've been having progressively better results with comparatively less time spent on each project! My panoramas are straightforward but I always shoot hand held, so lots of parallax errors!
My main question is: Given that we have more than one way of getting control points across all images, does it really help to have lots and lots of (good) control points? I mean, given a good result from a certain group of control points, is it reasonable to assume that if we can produce a number of extra good control points, then a further iteration will yield a better fitting? Of course having good control points comes down to shooting good images and discarding all the bad ones. This is where I get a great help from the fine tuning functionality. It is, however, still a bit of a mystery for me... Just after we fine tune all our control points, we get this message saying that: "problematic points can be spotted with a correlation <=0.900" and that points with a correlation of 0.0 are also bad (can't remember the exact text). But the issue is that the control point list dialog gives us the distance between the same point in their respective pair of images (I reckon; maybe I'm wrong...), not their correlation. I can't find the correlation values anywhere! Naturally good control points got better but I can't tell which points I should discard. I have read on this list that after fine tuning, the cp distance is actually their correlation (not sure if their values become equivalent or if this is a tweak to help the ignorant chap trying to make a decent panorama). The issue with this is that if I manually check one control point with a distanceof 0.31 (after fine tuning, before optimising) it seems fine - matches the exact same spot in both images. And if I check another with 1.00, it also matches... so I'm confused! This leads me to propose a couple of suggestions that would help the GUI in ease of use: - Offer to discard points with that low correlation value range (<=0.900). This would be an option that could appear on the dialog just after completion of a fine-tuning process or could be enabled on the control point list dialog just after the fine tuning process; - A column could be added to the control point list dialog to include the cp correlations... and perhaps an option to select by correlation value range... much like the button that's already there; The second part of this email is about another suggestion. It might seem dumb or it might not fit in anyone else's work flow, but if it does, maybe other people could benefit on it. If not, please disregard and don't take offence. Because I shoot hand held, I have lots of overlapping and that does not always help. So I end up taking out a few images - 20-40% of them generally - to improve fitting, seam and stitching quality. My suggestion was about iteratively optimising fitting with a single image taken out in an attempt to minimise error. Or in other words: 0. optimise, store maximum and RMS error values; set n=1; 1. remove image #n, optimise, store error values; 2. put image #n back, set n+=1, go back to step 1.; 3. compare all obtained error values; suggest to the user that if image #m is removed from the project, errors are minimised to X and Y, against the original values x and y; So this would be like minimising errors by removing any single image. It could be extended for multiple images, it could (and perhaps should) take into account the number and quality of control points linking images #n-1 and #n+1 just to check if it was worth the optimisation effort (but it can also be easier to optimise anyway and hope for higher error values if cps are bad), etc. Once more, huge respect for all your hard work on hugin & surrounding applications! It has been improving substantially at every step! Well done! Best regards, Pedro. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "hugin and other free panoramic software" group. A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/hugin-ptx -~----------~----~----~----~------~----~------~--~---
