I'm creating panoramas using lenses of different focal lengths. My technique is to take a strip of photos with a shorter focal length lens (say, 28 mm) and within that to take another strip of shots with a longer lens (e. g. 50 mm). This is useful for landscapes, for which having a lot of detail in the midground and horizon areas is important, but not so much is needed in the sky or in the extreme foreground (which typically frames the shot or would be out of focus anyway).
Hugin (7.0) in general doesn't have any problem with this, but there are three specific issues: 1) Fitting control points is problematic. Autopano actually does a decent job of finding points, but they're not all that accurately positioned, and manually creating control points and fine tuning them is much more difficult. It looks like what happens is if a control point is placed inside or outside of a corner or an edge, the placing algorithm doesn't take into account the difference in focal length. For example, if I place a point 4 pixels from a corner (vertex), the autoplacement algorithm places it 4 pixels from the corner in the other image, even if the focal lengths are different. Fine tuning is useless; I have to manually place the other side of the control point. 2) Enblend doesn't know to give preference to the shots taken with the longer focal length lens (i. e. the ones with more detail). The actual result depends upon the order of the images: if the short FL ones come first, they all get used, and then enblend ignores the long FL ones since they aren't actually needed, while if the long FL ones come first, the end result is a mosaic of long and short FL pieces. 3) It's possible to move single images up or down by means of the move up and move down buttons in the Images tab, but not multiple images at a time (if more than one image is selected, the move up and move down buttons are grayed out). The way I work around the second issue is as follows: * Use Hugin to generate discrete TIFF files. * Run enblend manually twice, once on the long FL images and once on the short FL ones. * Run gimp on the short FL composite. * Load the long FL composite as a separate layer above the short FL composite. * Crop the combined image to remove the areas with no image (I wish hugin could do that!). * Create a layer mask for the long FL layer using the alpha channel. * Show and edit the layer mask. * Use select by color on the layer mask (which is all black or white at this point). * Shrink the selection (of the layer mask!) by 50 pixels * Feather the selection by 50 pixels. * Invert the selection. * Bucket fill the selection with black (transparent, since we're editing the layer mask). This yields a blend zone 100 pixels wide. * Un-edit and un-show the layer mask. This yields a remarkably smooth blend zone with typical images, but it's a bit more work than I'd like to do manually. In particularly bad spots, such as crossing sparse foliage where the images aren't well-aligned due to wind or parallax error (I don't have a Nodal Ninja or the like), the transition is visible -- if you know exactly where to look -- but not objectionable. The first time I did this, I cut a hole out of the short FL composite (so I could pick exactly where I wanted the transition) and used enblend to merge them. That actually seems to yield inferior results -- most of the time -- to the rather simple-minded approach above. That seems to be because enblend uses too narrow a transition region in areas with detail, but that isn't always the right thing to do -- if the detail is highly repetitive with low information content (such as pine needles), a broad transition zone is more appropriate. This does yield some ghosts where things aren't aligned, but in the ones I've shot so far, those ghosts are typically individual leaves or twigs that aren't really much of a problem even if you do know exactly what you're looking for. Automating this workflow wouldn't be that hard, I'd think. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
