On 16 Dez., 18:49, Matthew Gates <matthew...@gmail.com> wrote: > On 14 December 2010 22:48, kfj <_...@yahoo.com> wrote:
> Well, we have tarballs with the original plate jpegs split into small > chunks. That's how the data arrived to us after some processing by > another The tarballs contain sub-directories x1 x2 x4 etc. x1 is > the highest res. Don't worry about the rest of the directories, they > are just lower resolution version of the same data. Okay, I had a first look at the tar ball you linked to. If I interpret the data correctly, x64 is the lowest resolution and shows the complete plate, and the other directories offer tiles at various resolutions, with the highest resolution images contained in x1, where there are 64*64 =4096 images. The data don't look to me as if they were suffering from significant vignetting. The background of the image has a slight reddish tint towards the center in the order of magnitude of 10 (out of 256), but I don't think that would translate into such a visible effect as can be seen on your sample stitch image. So I'm a bit puzzled - is this maybe just one plate where the problem we're trying to tackle isn't so visible? At any rate, to get an idea of the overall quality of the data, it would be useful to have a set of x64 plate images, covering an area of - or even better, the whole sky. If you have the data uncompressed somewhere you could just lump them together with a command like (including the appropriate metadata) tar cvf x64.tar S*/x64/*.jpg S*/x64/*.hhh The resulting tar file would be smaller than one of the pyramids, since it would only contain 1792 images, one for each tar ball. My reasoning here is that any vignette-like effect would be perfectly visible on the x64 image, the higher-res tiles would not offer too much extra information for the purpose at hand. The 1792 images at the lowest resolution would offer an idea of the overall problem and need for processing and, therefore, be more useful than an arbitrary pyramid with all resolutions - I suppose the x64 image is nothing but a compressed composite of the higher-res tiles anyway. The tiles come with a cornucopia of metadata, most of which exceed my admittedly narrow astronomic horizon - what I seem to have gleaned, though, is that the projection is gnomonic and localization of the individual images should be easy straight from the metadata. What I need for a trial stitch in hugin (from which we might be able to derive the vignetting data) is translation of the astronomical nomenclature in the hhh files into hugin's system. Hugin uses a notion of roll, pitch and yaw. I suspect roll will be zero for the images, pitch would refer to the center of the image and be in degrees from the equator and yaw to the center of the image in degrees from any reference point on the equator you care for, maybe you could point me to which of the metadata to touch for the purpose and how to translate them, if necessary. I suspect the relevant data are in the 'Hour Angle' and 'Zenith distance' data fields in the hhh file, hour angle could be translated straight into yaw, and Zenith distance would be pitch + 90 degrees? I could then extract them from the hhh files. Alternatively, put small files with the images containing roll, pitch and yaw in degrees - then I wouldn't have to do the extraction myself ;-) > The x64 directories in the .tgz files might be useful here, as they > are full-plate at low res. We could maybe extract these, experiment > with blending and even stitch them together into a panorama to check > it. 1792 300x300 tiles isn't so bad. > > I can do the extraction of this data on the server and create a single > archive file which should be a manageable size. Sounds very good; I fully agree, hope to see the data soon! with regards Kay -- 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
