Could Microsoft's Photosynth Have Been Free Software?

I don't know if the FLOSS community came up with it before Photosynth but there are a number of open source panorama applications around, and they have been around for some time.

I'll leave it as an exercise for the reader to find at least two such open source programs.

Photosyth isn't just a panorama application. With a panorama application you have to line up the pics yourself. Photosyth does that for you through image analysis.

autopano:

automatically create control points for panorama image Autopano-SIFT looks at your images and compares information about the images' content to order them correctly. Together with programs like hugin and enblend, you can create top-quality panorama images.

Warning: "The University of British Columbia has applied for a patent on the SIFT algorithm in the United States. Applications of this software may require a license from the University of British Columbia."

Hugin:

GUI tools for Hugin Hugin is a panorama photo stitching program. Essentially, Hugin is a GUI frontend for Panorama Tools. Stitching is accomplished by using several overlapping photos taken from the same location, and using control points to align and transform the photos so that they can be blended together to form a larger image. Hugin allows for the easy creation of control points between two images, optimization of the image transforms, and much more.

This package includes the following graphical interfaces, using the command-line tools provided in the hugin-tools package: * hugin - Hugin panorama creator * hugin_stitch_project - Hugin batch stitcher * nona_gui - Graphical interface for nona.

enblend (use hugin for autoalignment):

image blending tool Enblend is a tool for compositing images. Given a set of images that overlap in some irregular way, Enblend overlays them in such a way that the seam between the images is invisible, or at least very difficult to see. It can, for example, be used to blend a panorama composed of several images.

It uses a Burt & Adelson multi-resolution spline. This technique tries to make the seams between the input images invisible. The basic idea is that image features should be blended across a transition zone proportional in size to the spatial frequency of the features. For example, objects like trees and windowpanes have rapid changes in color. By blending these features in a narrow zone, you will not be able to see the seam because the eye already expects to see color changes at the edge of these features. Clouds and sky are the opposite. These features have to be blended across a wide transition zone because any sudden change in color will be immediately noticeable.

Enblend does not align images for you. Use a tool like Hugin or PanoTools to do this. The TIFFs produced by these programs are exactly what Enblend is designed to work with.