## PJ 3Q - Project - 3D volume using Eulerian angles, trilinear interpolation ||

(12/15/11)

PURPOSE

Computes projection(s) of a cubic volume according to three Eulerian angles. Reads angles from a document file. Uses trilinear interpolation.   Example.

 PJ 3F [Project - 3D volume using Eulerian angles, FBS interpolation ||] PJ 3Q RR [Project - 3D volume using Eulerian angles & create rings file ||] PJ 3 [Project - 3D volume using Eulerian angles, trilinear or FBS interpolation, single projection] PJ AT [Project - 3D volume using exponential Attenuation] PJ CYL [Project - 3D volume onto Cylinder] RT SQ [Rotate and Shift - image, Quadratic interpolation ||]

USAGE

.OPERATION: PJ 3Q

.INPUT VOLUME: vol001
[Enter the name of the volume whose projections are to be computed.]

[The projections are only computed for the voxels inside the sphere of this radius.]

.ANGLE NUMBERS OR SELECTION DOC. FILE NAME: 1-700 or SEL001
[Note nonstandard order here, number of angles preceeds angle file name. Enter selected angle numbers or name of a document file containing the selected angle numbers. Projections will only be calculated for the selected sets of angles from the following angles doc. file. (If you use a selection doc. file here then the selected numbers are taken from the first register (3rd col) in the doc. file.)]

.ANGLES DOC. FILE: ANGLES
[Enter the name of the document file containing the Eulerian angles for the projections. The angles have to be given in the order: psi, theta, phi. Projections will be calculated for every entry specified in the previous question. The projection is made as if the volume was rotated by the psi angle around the Z axis, followed by the theta angle around the original Y axis and then rotated by the Phi angle around the original Z axis.]

.TEMPLATE FOR 2-D PROJECTIONS: PRJ****
[Enter the template for the output files which will contain the 2-D projections.]

NOTES

1. For a projection of the whole volume (not the internal sphere only) give a radius larger than any linear dimension of the volume. Please note that usually such a projection is incorrect and the program takes much longer.

2. Since values are interpolated, projection through a volume containing a single point may give an image in which the max exceeds the original value. This is not a bug.

3. Implemented by: P. Penczek.

4. Psi, theta, & phi angles are placed in file header starting at location: 100

SUBROUTINES

PJ3Q_N, PREPCUB, WRITPRO_N, WPRO_N

CALLER

VTIL2