Potential and Challenge of Ankylography
The concept of ankylography, which under certain circumstances enables 3D; structure determination from a single view , had ignited a lively debate; even before its publication [2,3]. Since then, a number of readers requested; the ankylographic reconstruction codes from us. To facilitate a better; understanding of ankylography, we posted the source codes of the ankylographic; reconstruction on a public website and encouraged interested readers to; download the codes and test the method . Those who have tested our codes; confirm that the principle of ankylography works. Furthermore, our mathematical; analysis and numerical simulations suggest that, for a continuous object with; array size of 14x14x14 voxels, its 3D structure can usually be reconstructed; from the diffraction intensities sampled on a spherical shell of 1 voxel thick; . In some cases where the object does not have very dense structure,; ankylography can be applied to reconstruct its 3D image with array size of; 25x25x25 voxels . What remains to be elucidated is how to extend; ankylography to the reconstruction of larger objects, and what further; theoretical, experimental and algorithm developments will be necessary to make; ankylography a practical and useful imaging tool. Here we present our; up-to-date understanding of the potential and challenge of ankylography.; Further, we clarify some misconceptions on ankylography, and respond to; technical comments raised by Wei  and Wang et al.  Finally, it is; worthwhile to point out that the potential for recovering 3D information from; the Fourier coefficients within a spherical shell may also find application in; other fields.