Convert Arcs to Straight Line Segments – How to Guide

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I have a large number of geometries, currently stored in Oracle, some of which contain arc segments.

I need to convert these geometries into LRS (Linear Referencing System) format so I would like to convert all the arcs to straight line segments.

I may have to write something in PL/SQL but, being a lazy sort, I was rather hoping someone had done this before.

Doesn't have to be in PL/SQL, I also have ArcGIS for Desktop, MapInfo, GeoMedia and FME if any of those would do it.

Best Answer

In ArcGIS for Desktop, you can use the tool Densify.

Adds vertices along line or polygon features. Also replaces curve segments (Bezier, circular arcs, and elliptical arcs) with line segments.

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[GIS] How to convert a compound geometry (Oracle) to a geometry made of straight line segments only

The function that converts arc into straight segments is SDO_GEOM.SDO_ARC_DENSIFY. Documentation for Oracle 12c is at http://docs.oracle.com/database/121/SPATL/GUID-97E8BF76-34B8-48CA-94A4-96F16B01B60C.htm#SPATL1108

There are two formats for the function

SDO_GEOM.SDO_ARC_DENSIFY(     
  geom    IN SDO_GEOMETRY,      
  dim     IN SDO_DIM_ARRAY       
  params  IN VARCHAR2      
) RETURN SDO_GEOMETRY;

SDO_GEOM.SDO_ARC_DENSIFY(
  geom    IN SDO_GEOMETRY,      
  tol     IN NUMBER       
  params  IN VARCHAR2      
) RETURN SDO_GEOMETRY;

Diminfo is rather painful to write by hand and therefore the latter format suits better for ad hoc queries.

An usage example with tolerance=0.1 (vertices which are closer that 0.1 meter from each other are considered to be in the same place) and arc_tolerance of 50 m (at maximum 50 meters shift is accepted due to conversion of curve into polyline)

SDO_GEOM.SDO_ARC_DENSIFY(GEOMETRIE, 0.1, 'arc_tolerance=0.05 unit=km')

Best Answer

Related Solutions

[GIS] How to preserve arc linetype when exporting from .dwg to ArcGIS for Desktop

[GIS] How to convert a compound geometry (Oracle) to a geometry made of straight line segments only

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