Three-dimensional reconstruction from random projections: orientational alignment via Radon transforms.
A method for alignment of projections with unknown projecting directions towards a three-dimensional reference has been developed. The technique has been applied to the three-dimensional reconstruction from images of a frozen-hydrated preparation of 50S ribosomal subunits from Escherichia coli recorded in the electron microscope. The algorithm as used here combines the Single Exposure Conical Reconstruction Technique (SECReT) with a three-dimensional orientation search. The algorithm allows for the refinement of a reconstruction obtained with SECReT by refinement of the true projection angles, and by the inclusion of projections with a priori unknown random orientation. With model data it is demonstrated that the algorithm works reliably even for signal-to-noise ratios lower than 1.
Radermacher
M
M
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany 12201-0509.
D000465:Algorithms; D004926:Escherichia coli / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D008433:Mathematics; D008854:Microscopy, Electron / Q000379:methods*; D012270:Ribosomes / Q000648:ultrastructure*