topic Re: ITopologicalOperator.Buffer units in ArcObjects SDK Questions

ITopologicalOperator.Buffer units

TedRakel — Tue, 03 Mar 2015 00:34:51 GMT

The documentation for ITopologicalOperator.Buffer states that "The buffer distance is in the same units as the source shape that is being buffered". The source shape in my case is a point feature. How do I find out if I'm buffering that point by feet, meters, or inches? The dataset that the point feature is in has a spatial reference as follows:

NAD_1983_StatePlane_Tennessee_FIPS_4100_Feet
WKID: 2274 Authority: EPSG

Projection: Lambert_Conformal_Conic
False_Easting: 1968500.0
False_Northing: 0.0
Central_Meridian: -86.0
Standard_Parallel_1: 35.25
Standard_Parallel_2: 36.41666666666666
Latitude_Of_Origin: 34.33333333333334
Linear Unit: Foot_US (0.3048006096012192)

Geographic Coordinate System: GCS_North_American_1983
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_North_American_1983
Spheroid: GRS_1980
    Semimajor Axis: 6378137.0
    Semiminor Axis: 6356752.314140356
    Inverse Flattening: 298.257222101

Re: ITopologicalOperator.Buffer units

XanderBakker — Tue, 03 Mar 2015 01:14:13 GMT

The linearUnitName is Foot_US, so as the name suggests it is in feet.

Re: ITopologicalOperator.Buffer units

OwenEarley — Tue, 03 Mar 2015 02:57:26 GMT

If you need to figure out the units dynamically in ArcObjects you can do this using the IProjectedCoordinateSystem.CoordinateUnit property. This returns an ILinearUnit which has a Name property and MetersPerUnit property that is useful for any conversions you may need to apply to your buffer distance.