Hop Geometry Calculator

Hop Geometry Calculator

1. Geometry Calculator

The Geometry Calculator adds row-wise geometry calculations to Apache Hop. Every input row provides a geometry; the transform evaluates exactly one configured operation and adds one scalar output field, for example an area, a coordinate, an extent value or a validity flag.

1.1. Description

The transform accepts native Hop geometry values and geometry-compatible text or binary fields. It is designed for pipelines that derive measurements or diagnostics from geometries without an overlay, edit or reprojection step:

  • measurements: AREA, LENGTH, PERIMETER, WIDTH, HEIGHT

  • coordinates: X, Y, Z, CENTROID_X, CENTROID_Y, INTERIOR_POINT_X, INTERIOR_POINT_Y

  • extent: XMIN, YMIN, XMAX, YMAX

  • metadata and diagnostics: GEOMETRY_TYPE, NUM_POINTS, NUM_GEOMETRIES, IS_EMPTY, IS_VALID, IS_VALID_REASON, IS_VALID_ERROR_TYPE, IS_VALID_LOCATION_X, IS_VALID_LOCATION_Y, IS_SIMPLE, IS_SIMPLE_LOCATION_X, IS_SIMPLE_LOCATION_Y, SRID

Exactly one calculation is configured per transform. Chain several Geometry Calculator transforms to add more than one result to a row.

1.2. Input

The transform is a regular transform: it consumes one incoming row per row and returns the same rows with one added output field. It does not require a specific upstream transform.

Supported geometry sources:

  • native geometry values (ValueMetaGeometry) provided by the Geometry Type plugin

  • String and Binary fields whose name contains geom, geometry, wkt or wkb

  • WKT and EWKT text

  • WKB bytes and WKB hex text

SQL/MM curve types (CIRCULARSTRING, COMPOUNDCURVE, CURVEPOLYGON, MULTICURVE, MULTISURFACE) are parsed and preserved, including across isolated plugin class loaders.

The input field can be selected explicitly or left empty: an empty selection enables the automatic field detection, which resolves the geometry field by field name and value metadata.

1.3. Options

The transform dialog shows the following fields:

+==============================================================================+
| Geometry Calculator                                                          |
|                                                                              |
| Name                                                                         |
| [ Geometry Calculator                            ]                           |
|                                                                              |
| Input geometry field  [ geometry                                     v ]     |
| Operation             [ Area (Measurements)                          v ]     |
| Output field          [ area                                           ]     |
| Output type           [ NUMBER                                       v ]     |
| Error mode            [ RETURN_NULL                                  v ]     |
|                                                                              |
| Status: geometry field detected on the input.                                |
|                                                                              |
|                                                          [ OK ]   [ Cancel ] |
+==============================================================================+
Option Description Default

Input geometry field

Name of the field that holds the geometry. Leave empty to detect the field automatically.

(empty, auto-detect)

Operation

The calculation to apply, see Operations.

AREA

Output field name

Name of the added output field.

area

Output type

Hop type of the output field, see Output.

NUMBER

Error mode

RETURN_NULL or FAIL, see Error handling.

RETURN_NULL

1.3.1. Operations

Operation Result

AREA

Area of polygonal geometries.

LENGTH

Length of lineal and polygonal geometries.

PERIMETER

Perimeter of polygonal geometries.

WIDTH, HEIGHT

Extent of any parseable geometry; null for empty geometries.

X, Y, Z

Coordinate of non-empty points; Z is null when the point has no Z ordinate.

CENTROID_X, CENTROID_Y

Centroid of non-empty valid geometries.

INTERIOR_POINT_X, INTERIOR_POINT_Y

Interior point of any parseable geometry; null for empty geometries.

XMIN, YMIN, XMAX, YMAX

Envelope of any non-empty parseable geometry.

GEOMETRY_TYPE

Geometry type name; SQL/MM curves report CircularString, CompoundCurve, CurvePolygon, MultiCurve and MultiSurface.

NUM_POINTS, NUM_GEOMETRIES

Coordinate and geometry counts of any parseable geometry, including empty geometries.

IS_EMPTY

true for empty geometries only.

IS_VALID

JTS validation result for any parseable geometry.

IS_VALID_REASON

Validation message of invalid geometries (TopologyValidationError#getMessage); null for valid geometries.

IS_VALID_ERROR_TYPE

Stable symbolic name such as SELF_INTERSECTION or TOO_FEW_POINTS; null for valid geometries.

IS_VALID_LOCATION_X, IS_VALID_LOCATION_Y

Scalar coordinates of the validation error; null for valid geometries.

IS_SIMPLE, IS_SIMPLE_LOCATION_X, IS_SIMPLE_LOCATION_Y

Simplicity result and its error location; locations are null for simple geometries.

SRID

SRID of the geometry; null for SRID ⇐ 0.

1.4. Output

The transform adds exactly one output field.

Operation group Allowed output types

AREA, LENGTH, PERIMETER, WIDTH, HEIGHT, X, Y, Z, CENTROID_X, CENTROID_Y, INTERIOR_POINT_X, INTERIOR_POINT_Y, XMIN, YMIN, XMAX, YMAX, IS_VALID_LOCATION_X, IS_VALID_LOCATION_Y, IS_SIMPLE_LOCATION_X, IS_SIMPLE_LOCATION_Y

NUMBER, STRING

NUM_POINTS, NUM_GEOMETRIES, SRID

INTEGER, NUMBER, STRING

IS_EMPTY, IS_VALID, IS_SIMPLE

BOOLEAN, STRING

GEOMETRY_TYPE, IS_VALID_REASON, IS_VALID_ERROR_TYPE

STRING

Value semantics:

  • null input values produce null output values

  • empty geometries stay distinguishable from null

  • empty geometries are valid and simple; use IS_EMPTY to detect them

  • all calculations use the units and the CRS of the input geometry as-is

  • measurements of SQL/MM curves use the segmented JTS representation, see Limitations

1.5. Supported engines

Engine Status

Local (Hop local pipeline engine)

Supported; the released plugin is verified against this engine in CI.

LocalSingle (Hop local single threaded pipeline engine)

Not part of the test matrix.

Remote

Requires the same plugin and Geometry Type installation on the Hop server.

Beam engines (Beam*)

Not part of the test matrix. Geometry values are provided by the Geometry Type plugin and are not a Beam-native schema.

The transform does not restrict engines itself; the table describes the verified and tested scope.

1.6. Examples

Every example is a minimal pipeline with sample data and exactly one calculation.

1.7. Error handling

Mode Behaviour

RETURN_NULL

Parse, type and compatibility failures produce null output values. The transform counts the failures and logs one summary line at the end.

FAIL

The first parse, type or compatibility failure raises a HopException and fails the pipeline.

1.8. Limitations

  • No reprojection and no unit conversion: calculations use the geometry and its CRS as-is.

  • One calculation per transform; chain transforms for more results.

  • No formula parser, no overlay or edit operations.

  • AREA, PERIMETER, WIDTH and HEIGHT are planar calculations in the units of the geometry.

  • SQL/MM curves are preserved, but scalar calculations use the densified linear JTS representation that the curve classes expose through their JTS superclass. LENGTH, AREA and similar operations are segment-based, not analytic circle or arc calculations.

  • Validation and simplicity locations are exposed as scalar X/Y values only; no geometry output is produced.