VTK Legacy Reader/Writer Information Format

Overview

The legacy vtk data file readers / writers store certain vtkInformation entries that are set on vtkAbstractArray's GetInformation() object. Support is currently limited to numeric and string information keys, both single- and vector-valued. Only the information objects attached to arrays are encoded.

Array Metadata Blocks

A block of metadata may immediately follow the specification of an array. Whitespace is permitted between the array data and the opening METADATA tag. The metadata block is terminated by an empty line..

```

vtk DataFile Version 4.1

vtk output ASCII DATASET UNSTRUCTURED_GRID POINTS 6 float 0 0 0 1 0 0 0.5 1 0 0.5 0.5 1 0.5 -1 0 0.5 -0.5 1

METADATA COMPONENT_NAMES X%20coordinates Y%20coordinates Z%20coordinates INFORMATION 8 NAME Double LOCATION TestKey DATA 1 NAME DoubleVector LOCATION TestKey DATA 3 1 90 260 NAME IdType LOCATION TestKey DATA 5 NAME String LOCATION TestKey DATA Test%20String!%0ALine2 NAME Integer LOCATION TestKey DATA 408 NAME IntegerVector LOCATION TestKey DATA 3 1 5 45 NAME StringVector LOCATION TestKey DATA 3 First Second%20(with%20whitespace!) Third%20(with%0Anewline!) NAME UnsignedLong LOCATION TestKey DATA 9

CELLS 3 15 4 0 1 2 3 4 0 4 1 5 4 5 3 1 0

CELL_TYPES 3 10 10 10

CELL_DATA 3 FIELD FieldData 1 vtkGhostType 1 3 unsigned_char 0 1 1 METADATA COMPONENT_NAMES Ghost%20level%20information INFORMATION 1 NAME UNITS_LABEL LOCATION vtkDataArray DATA radians

```

As shown, a metadata block can have two sections, COMPONENT_NAMES and INFORMATION. The INFORMATION tag is followed by the number of information keys that follow.

COMPONENT_NAMES

If the METADATA block contains the line COMPONENT_NAMES, the following lines are expected to be encoded strings containing the names of each component. There must be one line per component.

INFORMATION

If the METADATA block contains the line INFORMATION, the number of information keys is read from the INFORMATION line and vtkInformation data that follows is parsed. The general form of a single valued information entry is:

``` NAME [key name] LOCATION [key location (e.g. class name)] DATA [value] ```

A vector information key is generally represented as:

``` NAME [key name] LOCATION [key location (e.g. class name)] DATA [vector length] [value0] [value1] [value2] ... ```

The exception is a string vector, which contains encoded entries separated by newlines.

Specific examples of supported key types:

vtkInformationDoubleKey

``` NAME Double LOCATION TestKey DATA 1 ```

vtkInformationDoubleVectorKey

``` NAME DoubleVector LOCATION TestKey DATA 3 1 90 260 ```

vtkInformationIdTypeKey

``` NAME IdType LOCATION TestKey DATA 5 ```

vtkInformationStringKey

``` NAME String LOCATION TestKey DATA Test%20String!%0ALine2 ```

vtkInformationIntegerKey

``` NAME Integer LOCATION TestKey DATA 408 ```

vtkInformationIntegerVectorKey

``` NAME IntegerVector LOCATION TestKey DATA 3 1 5 45 ```

vtkInformationStringVectorKey

``` NAME StringVector LOCATION TestKey DATA 3 First Second%20(with%20whitespace!) Third%20(with%0Anewline!) ```

vtkInformationUnsignedLongKey

``` NAME UnsignedLong LOCATION TestKey DATA 9 ```