The World Cup Lithomap Free 3D print model

This is a set of C source tools that generate lithophanes, 3D models made from images that reveal the image when lighted from behind. The tool "lithophane" generates traditional lithophanes in STL format from images in ppm format (use ImageMagick to convert from other formats). The tool "lithocup" generates lithophanes mapped to a cylindrical surface. As an example of the latter, I have included the "World Cup" cylindrical lithophane, which reveals a map of the earth when lighted from the inside.

Update: May 10, 2014: Added "margin" option on lithocup to continue cylinder past the edges of the image. Changed lithocup so natural orientation is textured side outward, "xflip" makes it smooth side out. Orientation of cylinder is now upright with respect to the XY plane surface.

Update: May 12, 2014: Added "binary" (-b) option on lithocup and lithophane to produce (much smaller!) binary STL files instead of ASCII files.

Update: May 26, 2014: Added "margin" (-m) on lithophane to generate a border around the picture, at the same thickness as the thickest part of the lithophane (default 3mm).

Update: December 30, 2014: Added "chamfer" (-c) option on lithophane to chamfer the corner borders. This can help alleviate the problem of having the corners lift off the bed during a print.

Update: December 30, 2014: Added "lithosphere.c", another version of the lithophane generator, that maps images onto spheres. This program has not been validated with an actual print yet. However, results are correctly manifold.