E4D User Guide

Visualization Utilities

Two utility programs, named px and bx are provided with the E4D distribution for visualization of meshes, and travel-time distributions.  These can be viewed in VisIt, a highly flexible visualization software capable of performing and visualizing a number of transforms on velocity and travel-time fields, or any specific function of those fields. Users are encouraged to review the VisIt documentation for details.

px is a python-language utility program that creates visualization files in xdmf/h5 format.  The xdmf file is loaded into VisIt which references an h5 file which contains the data.  The px program reads a list of command line specifications, and based on those specifications, reads E4D generated files as input and creates a corresponding xdmf and h5 file. The command line sequence for px is as follows:

px in_opt  e4d_mesh  file_opt  out_fil  t_stamp  variable_name (optional)

Command line option Description
in_opt

(string)           

 in_opt determines whether a new visualization file is created or an existing visualization file is appended.

in_opt = -f

Creates a new visualization file. If a file exists with the same name, it will be overwritten.

in_opt = -af

Append an existing visualization file.
e4d_mesh

(string)

 e4d_mesh is the prefix to the mesh files. For example, if the mesh file names are block.1.node, block.1.ele, block.1.neigh, block.1.face, and block.trn, then <e4d_mesh> is block

If the file append option –af is specified, then <e4d_mesh> must specify the same mesh that was used to build the original visualization files.

file_opt

(string)

 file_opt specifies either:

A single file name

Either a velocity or travel-time distribution.

A list file containing the file names

In the same format as the velocity list file

Files must have the same number of nodes (for a travel-time distribution) or elements (for a velocity distribution) as in the <e4d_mesh>.node or <e4d_mesh>.ele file.

out_file

(string)

 out_file is the prefix of the existing or new xdmf and h5 file.
t_stamp

(string)

 t_stamp is the time stamp specification for file_opt that is used in VisIt.
variable_name (optional)

(string)

 variable_name is the name of the variable(s) to be visualized in outfile in VisIT.
For mesh element file visualization, the default variable name(s) are Real_conductivity and Imag_conductivity.
In node file visualization, the default variable name(s) are Real_potential and Imag_potential.
If files to be visualized contains two variables, these names are separated by a space.

Example: Velocity visualization 

px -f two_blocks two_blocks.vel two_blocks 0 velocity
A new visualization file is created using the mesh element file two_blocks.1.ele with a velocity distribution specified in two_blocks.vel. Two files will be created called two_blocks.h5 and two_blocks.xmf. Within VisIt, a velocity variable will be viewable.
If variable_name is not entered, the name of the variable in VisIT will be Real_conductivity.

Example: Adding to an existing travel-time visualization 

px -af two_blocks two_blocks1.tt two_blocks_tt 10 travel_time
Existing visualization files, two_blocks_tt.xmf and two_blocks_tt.h5 are appended using the mesh node file two_blocks.1.node with a travel-time distribution specified in two_blocks1.tt. two_blocks_tt.h5 and two_blocks_tt.xmf will now contain the two_blocks1.tt distribution at time step 10. Within VisIt, a travel_time variable will be viewable for each time step.
If variable_name is not entered, the name of the variable in VisIT will be Real_potential.

bx is a fortran-language utility program that creates visualization files in exodus II format.  The .exo file can be loaded into VisIt for viewing. The bx program reads a list of command line specifications, and based on those specifications, reads E4D generated files as input and creates a corresponding .exo file. The command line sequence for bx is as follows:

bx in_opt  e4d_mesh  file_opt  out_fil  t_stamp

Command line option Description
in_opt

(string)           

 in_opt determines whether a new visualization file is created or an existing visualization file is appended.

in_opt = -f

Create a new visualization file. An existing file, if one exists, will be overwritten.

in_opt = -af

Append an existing visualization file
e4d_mesh

(string)

 e4d_mesh is the prefix to the mesh files. For example, if the mesh file names are block.1.node, block.1.ele, block.1.neigh, block.1.face, and block.trn, then <e4d_mesh> is block.1

Note: When using bx, e4d_mesh includes the suffix '.1.' For px, the '.1' is omitted.

If the file append option –af is specified, then <e4d_mesh> must specify the same mesh that was used to build the original visualization files.

file_opt

(string)

 file_opt specifies either:

A single file name

Either a velocity or travel-time distribution.

A list file containing the file names

In the same format as the velocity list file

Files must have the same number of nodes (for a travel-time distribution) or elements (for a velocity distribution) as in the <e4d_mesh>.node or <e4d_mesh>.ele file.

out_file

(string)

 out_file is the prefix of the existing or new exodus II file.
t_stamp

(string)

 t_stamp is the time stamp specification for file_opt.

Example: Velocity visualization 

bx -f two_blocks.1 two_blocks.vel two_blocks 0
A new visualization file is created using the mesh element file two_blocks.1.ele with a velocity distribution specified in two_blocks.vel. A files named two_blocks.exo will be created. Within VisIt, a real_conductivity variable (velocity in fact) will be viewable.

Example: Adding to an existing travel-time visualization 

bx -af two_blocks.1 two_blocks1.tt two_blocks_tt 10
An existing visualization file, two_blocks_tt.exo is appended using the mesh node file two_blocks.1.node with a travel-time distribution specified in two_blocks1.tt. two_blocks_tt.exo will now contain the two_blocks1.tt distribution at time step 10. Within VisIt, a real_potential variable (travel-time in fact) will be viewable for each time step.