NAME

       fdk - cone-beam reconstruction from projections using the FDK algorithm

       The  term FDK refers to the authors Feldkamp, Davis, and Kress who wrote the seminal paper
       "Practical cone-beam algorithm" in 1984.  Their paper describes a filtered back-projection
       reconstruction  algorithm  for cone-beam geometries.  The fdk program in plastimatch is an
       implmenetation of the FDK algorithm.

FDK USAGE

       The fdk program takes a directory of 2D projection images as input, and generates a single
       3D volume as output.

       The command line usage is:

          Usage: fdk [options]
          Options:
           -A hardware            Either "cpu" or "cuda" (default=cpu)
           -a "num ((num) num)"   Use this range of images
           -r "r1 r2 r3"          Set output resolution (in voxels)
           -f filter              Either "none" or "ramp" (default=ramp)
           -s scale               Scale the intensity of the output file
           -z "s1 s2 s3"          Physical size of the reconstruction (in mm)
           -I indir               The input directory
           -O outfile             The output file

       The  usage  of  the  fdk program is best understood by following along with the tutorials:
       fdk_tutorial_i and fdk_tutorial_ii.

INPUT FILES

       Three different formats of input files are supported.  These are:

       • Pfm format image files with geomtry txt files

       • Raw format image files with geomtry txt files

       • Varian hnd files

       The pfm and raw files are similar, in that they store the image  as  an  array  of  4-byte
       little-endian  floats.  The only difference is that the pfm file has a header which stores
       the image size, and the raw file does not.

       Each pfm or raw image file must have a geometry file in the same directory with  the  .txt
       extension.  For example, if you want to use image_0000.pfm in a reconstruction, you should
       supply another file image_0000.txt which contains the geometry.  A  brief  description  of
       the geometry file format is given in proj_mat_file_format.

       The sequence of files should be stored with the pattern:
          XXXXYYYY.ZZZ

       where  XXXX  is  a  prefix,  YYYY  is  a number, and .ZZZ is the extension of a known type
       (either .hnd, .pfm, or .raw).

       For example the following would be a good directory layout for pfm files:

          Files/image_00.pfm
          Files/image_00.txt
          Files/image_01.pfm
          Files/image_01.txt
          etc...

       The Varian hnd files should be stored in the original layout.  For example:

          Files/ProjectionInfo.xml
          Files/Scan0/Proj_0000.hnd
          Files/Scan0/Proj_0001.hnd
          etc...

       No geometry txt files are needed to reconstruct from Varian hnd format.

IMAGE GEOMETRY

       By default, when you generate a DRR, the image is oriented as if the virtual x-ray  source
       were a camera.  That means that for a right lateral film, the columns of the image go from
       inf to sup, and the rows go from ant to post.  The Varian OBI system produces  HND  files,
       which are oriented differently. For a right lateral film, the columns of the HND images go
       from ant to post, and the rows go from sup to inf.  An illustration of this idea is  shown
       in the figure below.
         [image] Geometry of Varian HND files.UNINDENT

AUTHOR

       Plastimatch  is  a  collaborative  project.   For  additional  documentation, please visit
       http://plastimatch.org.   For  questions,  comments,  and  bug   reports,   please   visit
       http://groups.google.com/group/plastimatch.

COPYRIGHT

       Plastimatch  development  team (C) 2010-2015.  You are free to use, modify, and distribute
       plastimatch according to a BSD-style license.  Please see LICENSE.TXT for details.