There are two files associated with the data, a .fld file, and a .dat file. the .fld is based on the AVS .fld format, with keyword value scheme. A typical .fld file is:
# AVS ndim=3 dim1=27 dim2=768 dim3=1024 nslices=1 nspace=3 veclen=1 data=byte field=uniform min_ext=0 0 0 max_ext=54 160 213.3333 variable 1 file=/scratch/u-staff/rks/l.dat filetype=parallelndim and nspace are always 3 (as we are only interested in 3D data). The terms nslices, veclen, data and field must all be present, with the values shown above, but are otherwise not significant to Volrend.
The dim1-3 parameters specify the extents of the data. The 3rd dimension is byte packed, so when creating the .dat file, you should declare a shape
shape [dim1][dim2][dim3/4] data_sh;to store the data to be written. See the file
trstoAVS.cs for
an example program to generate a .dat file.
The min_ext and max_ext arrays give the user coordinates for the data arrays. Volrend uses max_ext-min_ext to determine how long each axis is.
The final line gives the location of the data file. Volrend actually
looks for a directory (in the above case /scratch/u-staff/rks/l),
which contain the data file with different axis orientations to
eliminate the expensive need to transpose data for different display
orientations. To create this directory, use the orient 
utility.
Volrend will use an SDA if one is present to perform the I/O more efficiently, otherwise it will use the standard Unix file system. In this package, there are also some utilities tifftoAVS and trstoAVS which translate a collection of TIFF files or a single file containing just the data into the appropriate .dat format. Also included are various CMAVS modules that may be used to examine this data.