Parametric Objects

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

Circle: x=a+rcosɵ, y=b+rsinɵ (ɵϵ[0,2л))
Ellipse: x=acosɵ, y=bsinɵ (ɵϵ[0,2л))

The advantage of using parametric objects to express the geometric features of features is that when there are curves in the contour lines of real-world features, using parametric data for description makes the map display more closely fit the actual feature contours and more accurate in geometric calculations such as area and perimeter.
Figure Outline curve of the playground

Parametric Object Types

Currently, parametric objects supported for storage in line and region datasets include circles, arcs, ellipses, elliptic arcs, and 3rd-order poly bezier curves, as well as composite lines and region datasets composed of these parametric objects. Specific parametric object types are described as follows:

Parametric Object
Description
Parametric Object Graphic
Class Name
Arc
 
GeoArc
Circle
 
GeoCircle
Elliptic arc
 
GeoEllipticArc
Ellipse
 
GeoEllipse
Poly bezier
3rd-order poly bezier
GeoBezier3Curve
Parametric line
Can consist of the following geometries: polyline (GeoLine), arc (GeoArc), circle (GeoCircle), elliptic arc (GeoEllipticArc), ellipse (GeoEllipse), poly bezier (GeoBezier3Curve), with the end coordinate of the previous geometry coinciding with the start coordinate of the next geometry.
GeoCompoundCurv
Parametric region
Can consist of the following geometries: polyline (GeoLine), parametric line (GeoCompoundCurve), circle (GeoCircle), ellipse (GeoEllipse), with all geometries being closed.
GeoCurvePolygon
Parametric multiline
Composed of multiple sub-objects, each containing only one geometry, which can be: polyline (GeoLine), arc (GeoArc), circle (GeoCircle), elliptic arc (GeoEllipticArc), ellipse (GeoEllipse), parametric line (GeoCompoundCurve), poly bezier (GeoBezier3Curve). Specifically, when the sub-object is GeoLine, the contained line object count must be 1.
GeoMultiCurve
Parametric multipolygon
Composed of multiple sub-objects, each containing only one geometry, which can be: polygon (GeoRegion), parametric region (GeoCurvePolygon). Specifically, when the sub-object is GeoRegion, the contained polygon object count must be 1.
GeoMultiSurface

External Format Parametric Object Import

Currently supports importing parametric objects from DWG and FileGDB data, and parametric object import is supported in Windows_x86, Linux_x86, and Linux_arm environments.

  • DWG
    DWG Geometry
    Import as Line/Region Dataset
    Import as CAD Dataset
    Keep Parametric Object
    Do Not Keep Parametric Object
    Keep Parametric Object
    Do Not Keep Parametric Object
    Circle, ellipse
    Circle, ellipse
    Fitted polyline/polygon
    Circle, ellipse
    Circle, ellipse
    Arc, elliptic arc
    Arc, elliptic arc
    Fitted polyline
    Arc, elliptic arc
    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/polygon
    Fitted polyline/polygon
    Parametric line/polygon
    Compound

    * When importing polylines as CAD datasets, "keep parametric object" must be set, and parametric objects must exist, ignoring polyline width or when polyline width is 0, to import as parametric objects; otherwise, they will be imported as compounds.

    * When importing DWG as parametric objects, only 2D datasets are supported; if object height information is kept, it will be fitted to polylines.

  • FileGDB
    FileGDB Geometry
    Import Line/Region Dataset
    Circle, arc
    Circle, arc
    Poly bezier
    Parametric multiline with sub-object as poly bezier
    Circle, ellipse, parametric region
    Circle, ellipse, parametric region
    Line/polygon features composed of multiple line/region geometries (see Figure 2)
    Parametric multiline/parametric multipolygon

    * When a FileGDB line/polygon feature has multiple sub-objects (as shown below), import will convert it to a parametric multiline/parametric multipolygon containing multiple sub-objects.

    Figure Parametric multiline composed of multiple sub-objects
  • Other External Formats

    Parametric objects in other external formats will be fitted to polylines upon import.

Parametric Object Export to External Formats

Currently, parametric objects are kept only when exporting to DWG or DXF formats, and this is supported in Windows_x86, Linux_x86, and Linux_arm environments. Exporting to other formats, including those that do not support parametric objects, such as CSV, GeoJSON, KML, etc., will fit parametric objects to polylines.

Function 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, supported feature editing functions for parametric objects include only: erase, line to point, polygon to line, line to polygon, specify coordinates, specify orientation, specify offset, positioning copy, mirror, rotate.

Related Topics

Objects Overview