Differences between revisions 7 and 8
Revision 7 as of 2010-01-08 21:25:02
Size: 2563
Editor: penczek
Comment:
Revision 8 as of 2010-01-08 21:25:49
Size: 2561
Editor: penczek
Comment:
Deletions are marked like this. Additions are marked like this.
Line 7: Line 7:
 . Here are some examples of creating a Transform3D object. Much more here: [:http://blake.bcm.edu/emanwiki/Eman2TransformInPython:].  . Here are some examples of creating a Transform3D object. Much more here: [http://blake.bcm.edu/emanwiki/Eman2TransformInPython].

Name

Transform Class

Usage

Examples

All angles are in degrees

Creating just rotations:

  • RA=Transform3D(0,0,25); # Default is the ZXZ convention
  • RA=Transform3D(EULER_SPIDER,0,0,25); # This is the typical ZYZ convention
  • RA=Transform3D(m11,m12,m13,m21,m22,m23,m31,m32,m33) # create the transformation by entering
  • components

Creating more complicated transformations using set :

  • RA = Transform3D(); # this creates the 3D identity matrix
  • RA.set_rotation(0,0,25); # creates a matrix that will rotate 2D images by 25 degrees
  • RA.set_posttrans(Vec3f(1,0,0)); # the matrix will now also shift 1 pixel in the x-direction
  • RA.set_scale(1); # Occaisionally one will wish to rescale.

The following code will multiple (combine) two sets of Eulerian angles:

  • a=even_angles(2.,symmetry='d4',method="P",phiEqpsi = "Zero")
  • R2 = Transform3D(EULER_SPIDER,90.,0.,0.)
  • for i in xrange(len(a)):
    • R1 = Transform3D(EULER_SPIDER,a[i][0],a[i][1],a[i][2])
    • R3=R1*R2
    • compeuler = R3.get_rotation(EULER_SPIDER)
    • compphi = compeuler["phi"] ; compphi = (compphi +360.0)%360.0
    • comptheta = compeuler["theta"]; comptheta = (comptheta+360.0)%360.0
    • comppsi = compeuler["psi"]; comppsi = (comppsi +360.0)%360.0
    • print a[i]
    • print compphi,comptheta,comppsi

Notes:

  • a) We could have used EMAN, IMAGIC, SPIN, QUATERNION, SGIROT, MRC, XYZ, MATRIX instead of the SPIDER of EULER_SPIDER above.
  • b) There is also a set_rotation via a dictionary object, which we will explain at length soon.
  • c) The first two lines of the second block of commands, could have been written as the second line of the first block of commands. This command sets RA to a rotation that rotates a 2D image by 25 degrees around the Z-axis.
  • d) There are corresponding "get" calls to extract the information from the transformation matrices. SPARX has some of its own, that are wrappers for these get calls. More later.

Description

Purpose: to apply rotation/shift/scaling operations for 2D or 3D images via a variety of methods.

Author

P. R. Baldwin

Maintainer

P. R. Baldwin

Keywords

category 1
FUNDAMENTALS

Files

libEM

See also

Maturity

Infancy

Bugs

transformClass (last edited 2013-07-01 13:12:38 by localhost)