The Analysis and Display of Human Locomotion
The ANZ/Telio/Show3D package is a set of computer programs for use in the research as well as the clinical evaluation of human locomotion. Together, these allow the analysis, plotting, and graphical display in 3 dimensions of body segment kinematics and kinetics. The software is being made available in source code and executable form to facilitate researchers and clinicians in the development of their own locomotion analysis software.
AVAILABILITY
Source code and DOS executables of these programs as well as sample data and documentation are available in PKZIP archive files. Copies of hand written notes of the derivations of the kinematics and kinetics algorithms within ANZ are available in PDF format from the FTP site using the link below:
ftp://c3dftp:c3dftp@ftp.c3d.org/anz/
- ANZ uses measured marker trajectories to produce estimates of spatial limb kinematics, absolute and relative, including translational and rotational velocities and accelerations. These can be combined with force plate data to evaluate net joint resultant loads and joint power transfers. The majority of the analysis methods are based upon segmental local coordinate systems that are marker system independent. Several marker sets are currently supported including clinical full body marker sets (Helen Hayes, Ohio State, and Cleveland Clinic), a research full body marker set developed at Mayo Clinic, an upper extremity marker set, and a detailed foot kinematics marker set . Many general kinematics and kinetics procedures are included as well as a number of gait specific evaluations. In a number of evaluations, several methods are provided to do the same calculation to provide checking of algorithm validity. Muscle EMG data may also be processed with digital filtering. The program is command line based and can be operated interactively for exploratory analysis can be used repeatedly via command or batch files to yield a production environment for clinical gait evaluation. The results of an analysis are stored in a single binary format file constructed to be transportable between different computers. The contents of this file can be examined with Telio to produce graphs, Show3d to produce 3D figures, or exported from Anz in text format for further processing. The commands used to produce the analysis results are stored in the Anz binary file providing a history of the calculation process.
- TELIO is a command line driven program to graphically display the results of ANZ analyses. It can also read several data file formats native to the VICON marker tracking system. The program has a flexible display format so that screen displays and/or printouts can be produced using either time series or cross plotting of data. Data may be read from multiple files and a number of graphs generated at one time. A macro facility has been included to simplify generating complex displays. Combined with a command or batch file, printouts of data can be produced without any user interaction. Thus, the program functions as both an exploratory and a production display tool. A number of gait specific features are included to produce clinically useful gait displays. The VOGLE graphics subroutine library is used to provide device independent graphics capabilities. On the PC the program can display on a number of graphics adapters and produce print files in several formats including postscript.
- SHOW3D generates 3D views of marker trajectories and body segments as analyzed by Anz to allow visualization of motion from any direction. Body segments are represented by parallelepipeds to emphasize nonsagittal plane motions. Segments may be represented with hidden lines removed. A number of customization options are available including the display of the images on screen and/or via printed form. This program also uses the VOGLE graphics package. The program produces nice animations when used on a fast 486 PC.
SOURCE CODE
The source code uses VAX extensions to FORTRAN but no system specific routines, so it should be possible to use any FORTRAN compiler supporting VAX extensions. The PC versions of ANZ/TELIO/SHOW3D have been developed with the WATCOM 32bit FORTRAN compiler. In addition, the VOGLE graphics library has been customized for use with the WATCOM 32bit C compiler. Use of other compilers may require changes in the makefiles if not the source code of the programs. Presently, the software supports C3D files as well as Motion Analysis Corporation video and analog data files. The source code is rather large, totaling about 2.5 MBytes. The software is copyrighted and has been placed in the public domain as a research and instructional tool only and as such is UNSUPPORTED. The source code may be freely modified and redistributed for nonprofit purposes as long as the changes are clearly marked and the origin of the software, Dwight Meglan and The Ohio State University Gait Analysis Laboratory, is mentioned.
REQUIREMENTS
ANZ/TELIO/SHOW3D use a DOS extender so they must be run on 386 or better PC compatible computers. They are very disk and memory intensive - a legacy of their VAX origins. The executables are quite large- around 6 to 9 Megabytes and when running require at least 16MBytes of free disk space for a virtual memory swap file and a math coprocessor. The graphics programs, TELIO and SHOW3D, should work on EGA or better adapters though I recommend at least a VGA (SVGA is supported). The programs were developed on a 66MHz 486 with 16M RAM and run quite well on it. They have not been tested on other configurations.