VTK Metadata Export

ViennaPS supports exporting metadata to VTK output files. This feature allows users to embed additional simulation-specific and domain-specific information into the VTK files generated during surface, hull, or volume mesh output. The metadata is useful for post-processing, debugging, visualization, and reproducibility of simulation results.

Metadata can be selectively included in VTK output by setting a metadata level, which controls the amount and type of information written. Metadata export is configured on each Domain instance:

void enableMetaData(MetaDataLevel level = MetaDataLevel::PROCESS);
void disableMetaData();
auto getMetaDataLevel() const;

void addMetaData(const std::string &key, const std::vector<double> &values);
void addMetaData(const std::string &key, double value);
void addMetaData(const MetaDataType &metaData);
auto getMetaData() const;
void clearMetaData(bool clearDomainData = false);

Once enabled, metadata will be attached to future VTK output written by that domain.

Metadata Levels

The MetaDataLevel enum defines the available levels of metadata:

Level Description
NONE No metadata is written to VTK files.
GRID Domain-specific metadata only (e.g., grid spacing, boundary conditions).
PROCESS Includes domain metadata and parameters from the most recently applied process.
FULL Includes all available metadata, such as advection model settings, ray tracing parameters, etc.

The default level when enabling metadata is MetaDataLevel::PROCESS.

Usage Example 

// Create domain and apply process
auto domain = Domain<double, 3>::New();
domain->enableMetaData(MetaDataLevel::FULL);
...
Process<double, 3> process(domain, model);
process.apply();

// Write output
domain->saveSurfaceMesh("output_surface.vtp"); // Surface mesh with metadata

The resulting VTK file will now contain metadata including grid spacing, boundary conditions, and all relevant parameters from the applied process.

Python:

 
# Create domain and apply process
domain = vps.Domain()
domain.enableMetaData(vps.MetaDataLevel.FULL)
...
process = vps.Process(domain, model)
process.apply()

# Write output
domain.saveSurfaceMesh("output_surface.vtp") # Surface mesh with metadata

Process Metadata Behavior

  • Metadata at the PROCESS or FULL level always reflects the most recently applied process via .apply().
  • When a new process is applied to a domain, the previously stored process metadata is cleared and replaced with the current one.
  • Only one set of process metadata is retained per domain at any time.

Affected Output Types

Metadata is supported in the following mesh outputs:

  • Surface mesh (.vtp)
  • Hull mesh (.vtp)
  • Disk mesh (.vtp)
  • Level-Set mesh (.vtp)
  • Volume mesh (.vtu)

Each writer includes the metadata stored on the domain.

Notes

  • For deterministic and reproducible output, it is recommended to enable metadata before creating geometry or applying processes.
  • Metadata can also be added manually with addMetaData.