Parametric Objects

Parametric objects refer to geometries that use one or more parameters (such as angle, length, etc.) to represent (x,y) coordinate points. For example, circles and ellipses are expressed using parametric equations:

Circle: x=a+rcosθ, y=b+rsinθ (θ∈[0,2π))
Ellipse: x=acosθ, y=bsinθ (θ∈[0,2π))

The advantage of using parametric objects to represent geometric features is that when real-world feature contours contain curves, parametric data descriptions better match actual feature outlines in map display and improve accuracy in geometric calculations like area and perimeter.

Figure Contour Curve of a Playground

Parametric Object Types

Current line and region datasets support storing parametric objects including circles, circular arcs, ellipses, elliptic arcs, 3rd-order polybezier curves, as well as composite lines and regions formed by these parametric objects. Specific parametric object types are described below:

Parametric Object
Description
Graphical Representation
Class Name
Circular Arc
 
GeoArc
Circle
 
GeoCircle
Elliptic Arc
 
GeoEllipticArc
Ellipse
 
GeoEllipse
Polybezier
3rd-order polybezier
GeoBezier3Curve
Parametric Line
Can consist of: polyline (GeoLine), circular arc (GeoArc), circle (GeoCircle), elliptic arc (GeoEllipticArc), ellipse (GeoEllipse), polybezier (GeoBezier3Curve), with the endpoint of the previous geometry coinciding with the start point of the next geometry.
GeoCompoundCurve
Parametric Region
Can consist of: polyline (GeoLine), parametric line (GeoCompoundCurve), circle (GeoCircle), ellipse (GeoEllipse), with all geometries closed.
GeoCurvePolygon
Parametric Multiline
Composed of multiple sub-objects, each containing a single geometry type: polyline (GeoLine), circular arc (GeoArc), circle (GeoCircle), elliptic arc (GeoEllipticArc), ellipse (GeoEllipse), parametric line (GeoCompoundCurve), polybezier (GeoBezier3Curve). Specifically, when sub-object is GeoLine, it can only contain one line object.
GeoMultiCurve
Parametric Multipolygon
Composed of multiple sub-objects, each containing a single geometry type: polygon (GeoRegion), parametric region (GeoCurvePolygon). Specifically, when sub-object is GeoRegion, it can only contain one polygon object.
GeoMultiSurface

External Format Parametric Object Import

Currently supports importing parametric objects from DWG and FileGDB formats, supported on windows_x86, linux_x86, and linux_arm environments.

  • DWG
    DWG Geometry
    Import as Line/Region Dataset
    Import as CAD Dataset
    Keep Parametric Object
    Discard Parametric Object
    Keep Parametric Object
    Discard Parametric Object
    Circle, Ellipse
    Circle, Ellipse
    Fitted polyline/polygon
    Circle, Ellipse
    Circle, Ellipse
    Circular Arc, Elliptic Arc
    Circular Arc, Elliptic Arc
    Fitted polyline
    Circular Arc, Elliptic Arc
    Circular Arc, Elliptic Arc
    Spline Curve
    Parametric Line
    Fitted polyline
    Parametric Line
    Fitted polyline
    Polyline
    Parametric Line
    Fitted polyline
    Parametric Line
    Compound
    Hatch Pattern
    Parametric Region
    Fitted polygon
    Parametric Region
    Compound
    Block
    Parametric Line/Region
    Fitted polyline/region
    Parametric Line/Region
    Compound

    * When importing polylines as CAD Dataset, "keep parametric object" must be enabled and satisfy parametric object existence criteria. Polyline widths must be ignored or set to 0 to import as parametric objects; otherwise import as compound.

    * DWG import as parametric objects only supports 2D datasets. Object height information will be converted to polylines if retained.

  • FileGDB
    FileGDB Geometry
    Import as Line/Region Dataset
    Circle, Circular Arc
    Circle, Circular Arc
    Polybezier
    Parametric Multiline with polybezier sub-objects
    Circle, Ellipse, Parametric Region
    Circle, Ellipse, Parametric Region
    Line/Polygon features composed of multiple line/region components (See Figure 2)
    Parametric Multiline/Multipolygon

    * When FileGDB line/polygon features contain multiple sub-objects (as shown below), they will be imported as parametric multilines/multipolygons containing multiple sub-objects.

    Figure Parametric Multiline Composed of Multiple Sub-objects
  • Other External Formats

    Parametric objects from other external formats will be converted to polylines during import.

Exporting Parametric Objects to External Formats

Currently only supports keeping parametric objects when exporting to DWG and DXF formats, available on windows_x86, linux_x86, and linux_arm environments. Exports to other formats (including non-parametric formats like CSV, GeoJSON, KML) will convert parametric objects to polylines.

Functional Support

  • Current vector processing and analysis functions supporting parametric objects include: overlay analysis, buffer analysis, dissolve, regularize building, compute area, vector resampling, centerline from double lines, centerline from polygon, measure distance, smooth line/polygon, create random point, vector to raster, update attributes, edgematching, vector clip, line topology processing, eliminate, polygon aggregation, cluster and outlier analysis (Anselin Local Moran's I), hot spot analysis (Getis-Ord Gi*), etc.
  • Starting from SuperMap iDesktopX 2025 version, supported feature editing functions for parametric objects include: erase, line to points, polygon to lines, lines to polygon, specify coordinates, specify orientation, specify offset, positioning copy, mirror, rotate.

Related Topics

Feature Drawing Overview