Thanks for trying to help, but....I'm still confused.
> If you place the initial > seam in the middle and I assume you mean horizontal center at the top, > you would get a distance to the left image's boundary (indicated by > the red line) of zero while still having a small distance to the right > image's boundary (indicated by the green line just above the red one). Why zero ? If I start the line in the middle of the overlap wouldn't the horizontal distance between red and green borders exactly half of the overlap width ? I was trying to understand this with a friend of mine and apparently we are both dummy :-) Is the line generation based on something like the grassfire transform ? Are there details on how optimization works ? I guess one needs to find a line that does not pass thru mismatches (i.e. parallax or moving objects). Thanks again. On Jun 11, 7:04 pm, cspiel <csp...@freenet.de> wrote: > Hi there! > > On Jun 11, 10:25 am, tago <liquidt...@gmail.com> wrote: > > > I was trying to study and understand how Enblend algorithm works. > > I'm looking at the example inhttp://enblend.sourceforge.net/details.htm, > > where it says (just before the example) "The algorithm finds a line > > which is as far away as possible from the edges of the area where two > > images intersect". > > This is the correct description of Enblend's initial seam line > generation, i.e. before seam line optimization. Though I wouldd > prefer a more mathematical statement: > "The algorithm finds a line whose minimum distance to any edge > (of the overlap area) is maximal." [MAX-DIST] > > > Looking at the picture I wonder why the line starts at the upper left > > corner of the intersection, shouldn't it be in the middle? > > Nope. Think 2-dimensional. ;) The overlap areas can be > irregular. E.g., the overlap need not happen from "left-to-right", it > could be from "top-to-bottom" as well. In the general case two images > can overlap in multiple areas even in the no 2-pi wraparound case. > > OK, let us take a look at the example image. If you place the initial > seam in the middle and I assume you mean horizontal center at the top, > you would get a distance to the left image's boundary (indicated by > the red line) of zero while still having a small distance to the right > image's boundary (indicated by the green line just above the red one). > Thus, this construction violates MAX-DIST because the distance to the > red line is not maximal. > > Now, if you look _very_ closely at the example you will notice a tiny > "nose" at the top of the upper vertical segment of the seam line, > which violates MAX-DIST, too. The overhang there actually is a bug. > See SourceForge bug id #2160427. The nose can become pronounced with > irregularly shaped overlap areas. See the attachments to the bug > report. Regrettably, I have to deny you the pleasure of fixing it. > (Just kidding.) It has been corrected in the "staging" branch > revision 331: > http://bazaar.launchpad.net/~cspiel/enblend/staging/revision/331 > > > For sure I'm not understanding the purpose of Enblend. > > Neither do I. -- Now, will you buy me a beer? > > However, I understand the purpose of the initial seam line generation > step. Usually, the closer we get to an image border the more the > pixels suffer from distortion, aberration, etc. As Enblend deals with > re-mapped images it is furthermore exposed to the errors introduced by > the projection, which also can increase towards the images' edges. > So, we want to stay away from _any_ edge as far as possible. MAX-DIST > minimizes the combined "error" of both images participating in the > overlap. > > And in the next semester we shall learn about seam line > optimization... > > > If someone could enlighten me. > > Isn't it better to be enlightened than it is to be enblended? > > Cheers, > Chris --~--~---------~--~----~------------~-------~--~----~ 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 hugin-ptx@googlegroups.com To unsubscribe from this group, send email to hugin-ptx-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/hugin-ptx -~----------~----~----~----~------~----~------~--~---
