Intersect Features

ERDAS IMAGINE Help

HGD_Variant
16.5.2
HGD_Product
ERDAS IMAGINE
HGD_Portfolio_Suite
Producer

Category: Feature Analysis

Operator Pack: Feature Analysis

Associated Namespace: HexagonGeospatial.FeatureAnalysis.IntersectFeatures

Default

Show All Ports

Intersect Features Operator

Intersect Features  Show All Operator

Description

This operator constructs topology from the two sets of features and computes the topological intersection of those two sets based on the given spatial relationship.

For each pair of features from the FeaturesIn1 and FeaturesIn2 ports which spatially intersect according to the spatial relationship, a new feature is created in the FeaturesOut port representing the join between the two intersecting feature instances. All fields from the two sets of features are included in the FeaturesOut schema apart from input geometry fields, and the primary key of FeaturesOut is a composite (multi-field) key composed of the key field(s) from each of the two input sets of features. In order to ensure uniqueness of output field names, as well as predictability in the names of output fields, all output field names are suffixed with "_1" (for FeaturesIn1) or "_2" (for FeaturesIn2). In addition, a new primary geometry field is output which contains geometries for the face(s), edge(s), and/or node(s) at which the features intersect.

Input geometry fields are not passed through in the case of this operator (an exception to typical operator behavior) because of the pass-through of large amounts of data as a result of the input geometry being multiplied out to many possible output rows, resulting in an explosion in memory use and output dataset sizes. This also provides consistency with GeoMedia behaviors familiar to expectant users of this operator.

Any combination of area, linear, and point features is supported for each FeaturesIn port. Depending on the spatial relationship, the new geometry fields of FeaturesOut may include any combination of point (from an intersecting node), linear (from an intersecting edge), or area (from an intersecting face). For example, an area from FeaturesIn1 may intersect an area from FeaturesIn2 by touching at a point, by touching along a boundary, or by overlapping (see examples below).

If the primary geometry fields of the two sets of input features have different CRS's, then FeaturesIn2 is automatically transformed to match FeaturesIn1.

All geometry types are supported including arcs, composites, collections, and boundaries with holes. Z values are retained but one is selected according to context when there are multiple Z values at a node. Features with null geometry values are considered to intersect with no other features.

This is a global sink operator, as it uses topology. All input features must be processed together before the first resulting output feature can be accessed, rather than each feature streaming through one by one.

This diagram presents two sets of features. The brown features are submitted through FeaturesIn1, and the blue features through FeaturesIn2. Each geometry in the diagram represents a single feature instance, not a collection. Collections, arcs, and more are not represented here in order to avoid further complicating the diagram, but are fully supported.

.Intersect Features diagram 1

The following diagrams present in red the result of spatially intersecting the brown and blue features using the 8 different spatial relationships.

Intersect Features diagram 2 Intersect Features diagram 3

Intersect Features diagram 4 Intersect Features diagram 5

Intersect Features diagram 6 Intersect Features diagram 7

Intersect Features diagram 8 Intersect Features diagram 9

Limitations

  1. Both FeaturesIn1 and FeaturesIn2 must have a geometry field. If not, then an error will be generated.
  2. The operator always operates on the primary geometry field of FeaturesIn1 and FeaturesIn2.

Connections

Inputs

Name

Data Type(s)

Description

Shown by Default

Required

Default Behavior or Behavior (must exist if not Required, may exist itherwise)

FeaturesIn1

IMAGINE.Features

One set of input features to intersect.

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FeaturesIn2

IMAGINE.Features

Another set of input features to intersect.

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SpatialRelationship

IMAGINE.String

Defines the spatial relationship between two sets of features. Allowable values are:

  • Touch
  • Meet
  • Overlap
  • Contain
  • Contained By
  • Entirely Contain
  • Entirely Contained By
  • Spatially Equal

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Touch

GeometryFieldName

IMAGINE.String

Geometry field name for the output geometry.

FA_IntersectionFeatures

Outputs

Name

Data Type(s)

Description

Shown by Default

FeaturesOut

IMAGINE.Features

Output features containing all fields from FeaturesIn1 and FeaturesIn2 apart from the input geometry fields, plus a new primary geometry field, with each feature representing a pair of intersecting features (one from each input).

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Related Operators

Syntax

IntersectFeatures ( <FeaturesIn1>, <FeaturesIn2>, <SpatialRelationship>[, GeometryFieldName=<GeometryFieldName>] )