PDA

View Full Version : Re: C3D files



Andrew Dainis
11-01-1998, 11:37 PM
I agree with the comments summarized by Gerome Garthwaite, that the C3D parameter format is rather tricky. This design was necessitated by the requirement of flexibility and ease of access to the user. With respect to the recent postings I would like to point out a number of things that might prove to be useful.

1) All parameters may be accessed and modifed interactively by use of the PRM program that I provide on the anonymous NIH ftp site ftp://bmli1.cc.nih.gov/pub/c3d_files/. The program will acces PC-Intel, DEC, and SGI written data files, and also indicate which data type they are.

2) AMASS software transparently handles C3D files from the three CPU types (PC-Intel, DEC, SGI etc.), but Oxford Metrics software does not (it still recognizes only DEC). This has been the source of considerable confusion. The differences are due to the the way floating point (real*4) numbers are stored by each type of hardware.

3) A complete library of object code is available at the ftp site, with full documentation, for manipulating/creating parameters. However, it is 16-bit MS Fortran.

4) PRM will allow one to build a parameter section from scratch, but I do not recommend it. It is too easy to make a mistake. It is better to modify an existing parameter section using PRM or the library.

5) To create a C3D file one does not necessarily have to know how to access the parameter section. You can take the parameter block from any existing file and just insert it into the new file. You can use PRM to make any modifications to the parameter section before or after. The header record and data records are quite easy to write.


As the originator, and by default "keeper", of the C3D file format, I will be happy to answer questions of interpetation, etc., or receive comments regarding the file format.

Andy Dainis
adainis@cfw.com









I agree with the comments summarized by Gerome Garthwaite, that the C3D
parameter format is rather tricky. This design was necessitated by the
requirement of flexibility and ease of access to the user. With respect to the
recent postings I would like to point out a number of  things that might
prove to be useful.
 
1) All parameters may be accessed and modifed interactively by use of the
PRM program that I provide on the anonymous NIH ftp site ftp://bmli1.cc.nih.gov/pub/c3d_files/.
The program will acces PC-Intel, DEC, and SGI written data files, and also
indicate which data type they are.
 
2) AMASS software transparently handles C3D files from the three CPU types
(PC-Intel, DEC, SGI etc.), but Oxford Metrics software does not (it still
recognizes only DEC). This has been the source of considerable confusion. The
differences are due to the  the way floating point (real*4) numbers are
stored by each type of hardware.
 
3) A complete library of object code is available at the ftp site, with
full documentation, for manipulating/creating  parameters. However, it is
16-bit MS Fortran.
 
4) PRM will allow one to build a parameter section from scratch, but I do
not recommend it. It is too easy to make a mistake. It is better to modify an
existing parameter section using PRM or the library.
 
5) To create a C3D file one does not necessarily have to know how to access
the parameter section. You can take the parameter block from any existing file
and just insert it into the new file. You can use PRM to make any modifications
to the parameter section before or after. The header record and data records are
quite easy to write.
 
 
As the originator, and by default "keeper", of the C3D file
format, I will be happy to answer questions of  interpetation, etc., or
receive comments regarding the file format.
 
Andy Dainis
adainis@cfw.com