Feature Type

Purpose

This note defines the HAPI Feature Type categories that determine the mathematical routing of survey records.

Source Priority

HAPI User Manual.pdf
FeatureCatalogue.json
Feature Catalogue Specification.md

Definition

A Feature Type is the high-level mathematical channel assigned to a Feature_Code. It determines how HAPI groups records and what type of Civil 3D drafting output is produced.

Supported Feature Types

Feature Type	Meaning	Typical Output
`1POINT`	A feature represented by one coordinate.	COGO Point plus optional block reference.
`2POINT`	A feature whose length and orientation are defined by two points.	Block reference or connecting Feature Line.
`LINEAR`	A continuous open line string.	Civil 3D Feature Line, labels, flow arrows where applicable.
`POLYGON`	An enclosed or rectangle-derived shape.	Enclosing rectangle, closed Feature Line, scalable block, or polygonal symbol.

Feature Catalogue Distribution

The current FeatureCatalogue.json contains 197 feature entries in the following routing distribution:

Feature Type	Count
`LINEAR`	79
`1POINT`	70
`POLYGON`	41
`2POINT`	7

Rules by Feature Type

`1POINT`

A 1POINT feature is placed at a single surveyed coordinate. Some 1POINT features may support a Sizing_Number override if the feature must be treated as a rectangle-derived object.

`2POINT`

A 2POINT feature uses two consecutive points to determine orientation and length. Some 2POINT features may also support a Sizing_Number override.

`LINEAR`

A LINEAR feature represents an open continuous line string. It may support Clustering_Number logic to connect non-sequential records, and some linear features support curve-segment interpretation via Segment_Type_Indicator.

`POLYGON`

A POLYGON feature represents an enclosed shape. It may use:

predefined grouping lengths
Sizing_Number rectangle fitting
Clustering_Number irregular polygon closure
proximity thresholds from Global_Configuration

Relationship to Point Code Suffixes

Suffix Type	Main Feature Types Affected	Effect
Sizing_Number	`1POINT`, `2POINT`, `POLYGON`	Overrides default point count for rectangle construction.
Clustering_Number	`LINEAR`, `POLYGON`	Links related records that may be non-sequential.
Supplementary_Suffix	Selected feature-specific cases	Adds compound feature semantics.

Implementation Notes

Preferred planned functions:

ResolveFeatureType
RouteSurveyRecord
ProcessOnePointFeature
ProcessTwoPointFeature
ProcessLinearFeature
ProcessPolygonFeature

The Feature Type should be obtained from Feature_Catalogue, not inferred from the visible shape of a code string.

Open Questions

Confirm whether future C# plugin routing should preserve these four Feature Type names exactly or map them to richer domain classes.