## PJ 3Q RR - Project - 3D volume using Eulerian angles & create rings file ||

(4/17/06)

PURPOSE

Computes projection(s) of a 3D volume according to the three Eulerian angles. Creates a "Circular Rings File" for use by 'AP REF' or other 'AP' operations. This may be usefull for speeding up alignment.
(See align_overview.html for info on 'AP' operations.)

 PJ 3Q [Project - 3D volume using Eulerian angles, trilinear interpolation ||] RT SQ [Rotate and Shift - image, Quadratic interpolation ||] AP REF [Alignment - multi-reference, rotation & shift ||*]

USAGE

.OPERATION: PJ 3Q RR

.3-D INPUT FILE: vol001
[Enter the name of the volume whose projections are to be computed. This should be a cube!]

[The projections are computed only for the object inside the sphere of the given radius.]

.ANGLE NUMBERS OR SELECTION DOC. FILE NAME: 1-700 or SEL001
[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 hee then the selected numbers are taken from the first register 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. The meaning of the angles is the same as in operation 'RT SQ'. Projections will be calculated for every entry specified in the previous question.]

.FIRST, LAST RING, & RING SKIP: 5,80, 1
[Only rings with radii in the range 5-80 will be analyzed. If skip=0 or 1, then every ring between 5 and 80 will be taken; for skip=2, every second ring; etc.]

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

.REFERENCE RINGS FILE: ref_rings
[Enter the template for the output files which will contain the reference rings (polar coordinate representation) of the 2-D projections. This file can be used by 'AP REF'.]

NOTES

1. Memory requirements: NX*NY+12*R**3+15*R**2, where R is the radius, but no more than: 6*NX*NY + NX*NY*NZ

2. The projection file has always dimensions NX x NY.

3. 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!

4. Implemented by: P.Penczek & A. Leith.

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

6. Use: 'MD' with option 'FBS ON' to get higher resolution projection than the linear interpolated default operation.

SUBROUTINES

PJ3Q_N, PREPCUB, WRITPRO_N, WPRO_N, WPRO_FBS, FBS3

CALLER

VTIL2