VizSchema

**Welcome to VizSchema-4** 

VizSchema is a prescription for specifying visualization semantics: the attributes that one must attach to meshes and dataset in HDF5 files so that the data can be visualized. Lately it is being generalized to define provenance specification: information about how the data was generated. Eventually this metadata will be separated, and VizSchema will be only about visualization. 

VizSchema visualization has been implemented in a plugin (called Vs) for the VisIt visualization tool and in a set of python scripts that plot using matplotlib. There are plans (though not immediate) to build a plugin for ParaView. 

For now, cross-file issues (e.g., mesh in one file with data in another) are not being addressed. 

**Building**

As of VisIt 2.0.0, the VizSchema database plugin is included with the VisIt distribution (source or binary). As a result, most users will be content with the copy of VizSchema that comes with VisIt.

**Developers**

The preferred method for working on the VizSchema plugin is to download and build VisIt from source code. This will set up the build system and will build the latest version of the plugin.

 * [[HowToDevelop|How to develop]]

 * [[VsTests|How to run Regression Tests (required before any check-in)]]

 * [[DevelopmentHints|Hints for Developers]]

*Tips for running remotely*

[[OnFranklin|Instructions for using franklin.nersc.gov as a remote viz server.]]

*Visualization tips and tricks*

[[Animation|Animating time series]]

*General principles of VizSchema*

* The user chooses the names of any group or dataset. 

* One should be able to add schema data to any file to make it vizschema compliant. 

* VizSchema attribute names begin with "vs". 

* Instead of a group with attributes and one dataset, have a dataset with attributes. 

* Spatial limits go with meshes, as those determine locations. 

* Time goes with data, as a mesh can be used at many times. 

*Visualization semantics*

* [[Meshes|Meshes and their metadata]] 

* [[Variables|Variables and their metadata]] 

* [[VariablesWithMesh|Variables that are combined with their meshes]] 

* [[DataOrdering|Data ordering]] 

* [[DerivedVariables|Variables defined in terms of other variables]] 

* [[MultiDomainMetaData|Multidomain metadata]] 

* [[OtherMetaData|Other metadata]]

*Provenance metadata*

* [[ProvenanceMetaData|Provenance metadata]]

*Tools*

* [[AddingMetadata|Adding Metadata to existing files]]

* [[PartialLoads| Partial Loading of datasets]]

*Schema and Processing Tools Development*

* [[SchemaDevelopment|Schema and Tools]] Information for developers on the formal schema specification and related processing tools.

---

*Sample Visualizations*

!swimrun.png!

Plot of quantity P from NIMROD dataset swimrun0031_20000_p100.h5.

Pseudocolor plot generated by VisIt using the VizSchema plugin.

!precip1.png!

Plot of global precipitation on cubed sphere mesh from CDAT project.

Pseudocolor plot generated by VisIt using the VizSchema plugin.

!sciDacImage475sm2.png!

Visualization of the A15 crab cavity. The magnetic fields lines are shown in red, the electric field lines are shown in green, the colors on the wall interior represent the intensity of the magnetic field on the wall. 

Pseudocolor plot generated by VisIt using the VizSchema plugin.

!T_e_coupled.png!

Visualization of electron temperature in an FACETS integrated (core and edge) simulation. Uses several files with multidomain markup. 

You can try attachment:crabcavpython3p_pycavity_1.h5 or attachment:core-edge-explicit_edge_1.h5 files yourself.