3D Reconstruction: Backprojection
Outline of the 3D reconfiguration method
There are several methods usable for 3D reconfiguration. The methods to be performed by Eos are the below. 1. Simple Backward projection (Eos): Used to perform backward projection simply. 2. Weighted backward projection (Eos): 3. Filtered Backprojection (Backward projection with a filter): Used to give weight in the Fourier space based on the projection angle of the projected image. This method is often used when a low-pass filter is applied to one-axis projection (tomography). 4. Iterative method 4.1 SIRT method (Simultaneous Iterative Reconstruction Technique) 4.2 ART method (Algebric Iterative Reconstruction Technique) (not supported yet) 5. Radon transformation method (Eos)
In the exercise, the weighted backward projection method is used.
IX-2. Practice of the 3D reconstruction
A program to perform the 3D reconstruction method by the weighted backward projection is as follows:
.3dlst.3d: mrc2Dto3D -I $(TARGET).3dlst -o $(TARGET).3d -InterpolationMode 2 -Double -DoubleCounter $(TARGET).3dcounter -CounterThreshold 0.5 -m 1 -WeightMode 2
“$(TARGET).3dcounter” shows the weight of Fourier Transform to be filtered by back-projection. If $(TARGET).3d and $(TARGET).3dcounter files are available, 3D images can be averaged using mrcImageAverage.