File formats from various codes often present challenges in dealing with the data the contain. For example, some files write a file per time step using a naming scheme that VisIt does not group automatically. Other formats may write a single file per processor, which would make viewing the whole in VisIt challenging. To address these issues, VisIt supports .visit files. A .visit file is a simple text file that lets you specify a list of filenames and how they are related.
To create a .visit file, simply make a new text file that contains the names of the files that you want to visualize and save the file with a .visit extension.
- VisIt will take the first entry in the .visit file and attempt to determine the appropriate plugin to read the file.
- Not all plugins can be used with .visit files. In general, MD or MT formats sometimes do not work.
- An MT file is a file format that provides multiple time steps in a single file. Thus, grouping multiple MT files to produce a time series may not be supported.
- An MD file is one that provides multiple domains in a single file. Thus, grouping multiple MD files to produce a view of the whole may not be supported.
Grouping a set of files as time steps
Here is an example .visit file that groups time steps together. These files should contain 1 time step per file.
timestep0.silo timestep1.silo timestep2.silo timestep3.silo ...
Grouping a set of files into a whole dataset
Here is an example .visit file that groups various smaller domain files into a whole dataset that VisIt can visualize. Note the use of the !NBLOCKS directive and how it designates the number of files in a time step that constitute the whole domain. In this example, we have 2 time steps each composed of 4 domain files.
!NBLOCKS 4 timestep0_domain0.silo timestep0_domain1.silo timestep0_domain2.silo timestep0_domain3.silo timestep1_domain0.silo timestep1_domain1.silo timestep1_domain2.silo timestep1_domain3.silo ...
- The !NBLOCKS directive must be on the first line of the file.