IGeometryServer Interface
Provides access to standard operations on geometric 'value' objects. The input geometries are never modified by these operations. Designed for use in building web services and web applications.
Description
This interface is new at ArcGIS 9.3.
Members
Name | Description | |
---|---|---|
Buffer | Buffers an array of geometries by each distance specified in an array of distances. The distance units can optionally be specified. Geometries buffered at a given distance can optionally be unioned together. | |
Densify | Applies the ArcObjects 'Densify' operation to each element of the geometry array. | |
FindSRByWKID | Defines an SR based upon its well known identifier (WKID) and optionally a WKID for a vertical datum. The resolution and xy tolerances are either computed from the sr horizon or set to defaults. 'authority' is typically either 'EPSG' or 'Esri'. | |
FindSRByWKT | Defines a spatial reference object based upon its well known text string (WKT) and optionally a WKT for a vertical datum. The resolution and xy tolerances are either computed from the sr horizon or set to defaults. The output sr is always high precision. | |
FindUnitsByWKID | Defines a unit object based upon its well known identified (WKID). 'authority' is typically either 'EPSG' or 'Esri'. | |
FindUnitsByWKT | Defines a unit object based upon its well known text string. | |
GetAreasAndLengths | Calculates areas and perimeter lengths for each polygon in the specified array. | |
GetLabelPoints | Calculates an interior point for each polygon. | |
GetLengths | Calculates the length of eacch polyline in the specified array. | |
Project | Projects an array of geometries from their current spatial reference (pInSR) to a destination spatial reference (pOutSR). The projection process can optionally include a datum transformation if the source and destination SRs have different GCSs. | |
Relation | Determines the pairs of geometries from the input geometry arrays that participate in the specified spatial relation. | |
Simplify | Applies the ArcObjects 'Simplify' operation to each element of the geometry array. |
IGeometryServer.Buffer Method
Buffers an array of geometries by each distance specified in an array of distances. The distance units can optionally be specified. Geometries buffered at a given distance can optionally be unioned together.
Public Function Buffer ( _
ByVal pInSR As ISpatialReference, _
ByVal pBufferSR As ISpatialReference, _
ByVal pOutSR As ISpatialReference, _
ByVal pDistances As IDoubleArray, _
ByVal pUnit As IUnit, _
ByVal bUnion As Boolean, _
ByVal pInGeometries As IGeometryArray _
) As IGeometryArray
public IGeometryArray Buffer (
ISpatialReference pInSR,
ISpatialReference pBufferSR,
ISpatialReference pOutSR,
IDoubleArray pDistances,
IUnit pUnit,
bool bUnion,
IGeometryArray pInGeometries
);
Remarks
Applies the geometric buffer operation to each geometry in pInGeometries, using each distance in the array pDistances. All geometries are assumed to be in the coordinate system pInSR, which cannot be nil. pBufferSR is the spatial reference in which the geometries are buffered. pOutSR is the spatial reference in which the buffer polygons are returned. pInSR must be specified. Either or both of the other SRs can be null. If the output spatial reference is null, then the input spatial reference is used for output; if the buffering spatial reference is null, then the output spatial reference is used for buffering; if both output and buffer spatial references are null, then the input spatial reference is used.
The distances can be specified in a separate unit of measure. For example, the buffer distances could be specified in feet and the coordinates of the geometries could be specified in meters. If bUnion is false, each buffered polygon will be added to ppOutBuffers separately. If bUnion is true, then all geometries buffered at a given distance will be unioned into a single (possibly multipart) polygon and that unioned geometry will be placed in the output array.
The SpatialReference property for all returned geometry will be null. It is the consumers responsibility to assign the spatial reference to each geometry returned, if desired. In this case, the spatial reference is assumed to be the output spatial reference defined for the Buffer operation.
Refer to IGeometryServer for additional details on how the input spatial reference is interpreted.
Buffering of geometries with latitude-longitude coordinates is only supported for points and multipoints. In order to meaningfully buffer polylines and polygons with such coordinates, you need to specify a planar (projected) coordinate system in which the buffering will happen. Use the BufferSpatialReference parameter to define this coordinate system. When the Buffer method is called, the input features will be projected into this coordinate system (BufferSpatialReference), buffered, and then either inverse projected into the original coordinate system (InSpatialReference) or projected into the output coordinate system (OutSpatialReference).
When buffering points or multipoints and the input spatial reference is a geographic coordinate system (WGS1984, for example), you have the option of generating true geodesic buffers. To obtain such buffers, specify a linear unit of distance for the pUnit parameter.
Here is an example showing how to create a buffer using the Geometry Server.
IGeometryServer.Densify Method
Applies the ArcObjects 'Densify' operation to each element of the geometry array.
Public Function Densify ( _
ByVal pSR As ISpatialReference, _
ByVal pInGeometries As IGeometryArray, _
ByVal maxSegmentLength As Double, _
ByVal useDeviationDensification As Boolean, _
ByVal densificationParameter As Double _
) As IGeometryArray
public IGeometryArray Densify (
ISpatialReference pSR,
IGeometryArray pInGeometries,
double maxSegmentLength,
bool useDeviationDensification,
double densificationParameter
);
Remarks
Replaces each curve segment, and optionally each line segment, in a polyline or polygon with line segments. Other types of input geometries will be ignored. All geometries are assumed to be in the spatial reference pSR, which cannot be nil.
When maxSegmentLength is greater than zero, lines and curves greater than that length will be replaced with lines at most maxSegmentLength long, and curves shorter than that will be replaced with lines connecting their endpoints. If maxSegmentLength is 0, then only curve segments will be densified, as explained below.
In general, this method provides three ways to densify curves:
- based on length
- based on central angle
- based on maximum distance of replacement line from input curve (deviation)
The following table explains how the input parameters work together.
When MaxSegmentLength is | and angleOrDeviation is | then |
---|---|---|
> 0 | 0 | All segments longer than maxSegmentLength are replaced with sequences of lines no longer than maxSegmentLength. Curves shorter than maxSegmentLength are replaced with lines connecting the curve endpoints. This is method 1, above, for densifying curves. |
0 | > 0 | Input lines are copied to the output geometries. Input curves are densified using either method 2 or method 3, based on the value of the useDeviationDensification parameter. |
> 0 | > 0 | Lines longer than maxSegmentLength units are replaced with sequences of lines no longer than maxSegmentLength; curves are replaced with sequences of lines using either method 2 or method 3, based on the value of the useDeviationDensification parameter. |
When UseDeviationDensification is false the DensificationParameter is interpreted as a central angle, instead of a deviation.
Refer to IGeometryServer for additional details on how the input spatial reference is interpreted.
If the geometries are in a geographic coordinate system, then “linear” densification distances are in units of degrees (or some other gcs angular unit). This isn’t meaningful if you expect output segments to have a constant ground length, but it still accomplishes the purpose of densifying the geometries, which is useful if you subsequently want to project them more accurately.
IGeometryServer.FindSRByWKID Method
Defines an SR based upon its well known identifier (WKID) and optionally a WKID for a vertical datum. The resolution and xy tolerances are either computed from the sr horizon or set to defaults. 'authority' is typically either 'EPSG' or 'Esri'.
Public Function FindSRByWKID ( _
ByVal authority As String, _
ByVal wkid As Integer, _
ByVal WKID_Z As Integer, _
ByVal bDefaultXYResolution As Boolean, _
ByVal bDefaultXYTolerance As Boolean _
) As ISpatialReference
public ISpatialReference FindSRByWKID (
string authority,
int wkid,
int WKID_Z,
bool bDefaultXYResolution,
bool bDefaultXYTolerance
);
Remarks
Returns a predefined, high precision spatial reference based on its OGP/EPSG Well Known Identifier (WKID, aka “factory code”). Valid WKID_s are listed below. If _WKID_Z > -1, then a vertical coordinate system will be created and associated with the horizontal coordinate system.
AuthorityName is usually "EPSG" or "ESRI", but can also be an arbitrary string. It can also be the empty string if you want the default authority name associated with the new spatial reference. Clients can associate their own authority names with factory codes that are currently associated with the EPSG or ESRI authority names, because only the WKID is used to create the spatial reference. Here are the current rules for mapping WKID ranges to default authority names:
• A WKID in the EPSG code range (1000 – 32768) will result in an AUTHORITY name of “EPSG”, and the version will be the current EPSG version used (currently “6.12”).• A WKID in the ESRI code range (33000 – 199999) will result in an AUTHORITY name of “ESRI”, and the version will be the current PE library version (currently “9.3”).• A WKID in the user (objedit) range (200000 – 209199) will result in an AUTHORITY name of “CUSTOM”, with no version associated with it. This name is specified by the OGC.
For web service clients of the geometry server, the returned WKT (well known text) element of the spatial reference will have an “AUTHORITY’ tag in it, containing the default or the client-specified authority name and the specified WKID.
If bDefaultXYResolution is true, then the xy coordinate grid resolution will be set to its default value (see SetDefaultXYResolution for details). If it is false, the finest possible resolution that covers the horizon of the spatial reference will be used (see ConstructFromHorizon for details).
If bDefaultXYTolerance is true, then the default xy tolerance of 1mm will be used (see SetDefaultXYTolerance for details). If it is false, then the minimum xy tolerance will be used (2.0 * xy coordinate grid resolution).
Lists of the valid WKIDs for predefined Projected Coordinate Systems can be found here:esriSRProjCS2Type, esriSRProjCS3Type, esriSRProjCS4Type, esriSRProjCSType
Lists of the valid WKIDs for predefined Geographic Coordinate Systems can be found here:
esriSRGeoCS2Type, esriSRGeoCS3Type, esriSRGeoCSType
Default XY Resolution values
SpatialReference type | Precision | Default value |
---|---|---|
ProjectedCoordinateSystem | high | 1/10 mm |
ProjectedCoordinateSystem | low | 1 mm |
GeographicCoordinateSystem | high | 1/10,000 arc-second |
GeographicCoordinateSystem | low | 1/500 arc-second |
UnknownCoordinateSystem | high | 1/10 mm |
UnknownCoordinateSystem | low | 1 mm |
Defining an XY resolutionDefining an XY resolution for a spatial reference depends on the type and precision of a coordinate system. For high precision spatial references, the domain extent and resolution must be sufficient to cover the horizon of a given coordinate system. For low-precision spatial references the domain extent is centered on the horizon center.
For a high precision ProjectedCoordinateSystem (PCS), the domain extent is a square completely covering, and slightly larger than, the horizon extent of the PCS (which is an arbitrary rectangle). The scale factor (1/precision) is chosen to fit this domain. For a low precision PCS, the center of the domain extent is aligned with the center of the horizon extent and expanded to achieve a target resolution of 1mm.
For a high precision GeographicCoordinateSystem (GCS), the square domain (-400, -400, 400, 400), expressed in the units of the spatial reference, is used. For a low precision GCS the upper right hand corner is adjusted to achieve a default resolution of 1/500 of an arc-second.
For an UnknownCoordinateSystem (UCS), the "horizon" is defined to be a square that produces a resolution of 1 millimeter for a low precision UCS or 1/10 mm for a high precision UCS.
Default XY Tolerance calculationsFor a ProjectedCoordinateSystem or an UnknownCoordinateSystem, the default tolerance is 1 mm (expressed in the units of the spatial reference) or 2.0 * XYResolution, whichever is larger. For a GeographicCoordinateSystem, it is the angle subtending 1 mm at the equator, or 2.0 * XYResolution, whichever is larger. The minimum allowable XYTolerance is 2.0 * XYResolution. If the default XY tolerance is not greater than or equal to 2.0 * XYResolution, the XYTolerance will be set at 2.0 * XYResolution.
IGeometryServer.FindSRByWKT Method
Defines a spatial reference object based upon its well known text string (WKT) and optionally a WKT for a vertical datum. The resolution and xy tolerances are either computed from the sr horizon or set to defaults. The output sr is always high precision.
Public Function FindSRByWKT ( _
ByVal wkt As String, _
ByVal WKT_Z As String, _
ByVal bDefaultXYResolution As Boolean, _
ByVal bDefaultXYTolerance As Boolean _
) As ISpatialReference
public ISpatialReference FindSRByWKT (
string wkt,
string WKT_Z,
bool bDefaultXYResolution,
bool bDefaultXYTolerance
);
Remarks
Finds a predefined spatial reference based on its OGC/EPSG definition string, otherwise known as its well-known text string (WKT). The text string contains individual parameters of a spatial reference. A valid spatial reference for a geographic coordinate system (GEOGCS) may appears as follows:GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]
Note the nested structure of parameters includes a datum, spheriod, prime meridian, and angular unit.A valid spatial reference for a projected coordinate system (PROJCS) may appears as follows:PROJCS["WorldMercator",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]], PROJECTION["Mercator"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER["Standard_Parallel_1",0.0],UNIT["Meter",1.0]]]Note the nested structure of parameters includes a geographic coordinate system (GEOGCS), a projection, and a set of projection parameters such as false easting, false northing, and standard parallel.If _WKT_Z is specified and not empty, then a vertical coordinate system will be created and associated with the horizontal coordinate system. The definition string can be generated from ArcObjects using the ExportToESRISpatialReference method on a PCS or GCS. The boolean parameters are as described for FindSRByWKID.
IGeometryServer.FindUnitsByWKID Method
Defines a unit object based upon its well known identified (WKID). 'authority' is typically either 'EPSG' or 'Esri'.
Public Function FindUnitsByWKID ( _
ByVal authority As String, _
ByVal wkid As Integer _
) As IUnit
public IUnit FindUnitsByWKID (
string authority,
int wkid
);
Remarks
Finds a predefined linear or angular unit of measure based on its OGP/EPSG well known identifier (WKID, also referred to as �factory code�). AuthorityName is optional. If specified, it is usually either "EPSG" or "ESRI", but can also be an arbitrary string. As with spatial references, only the WKID value is used to locate the predefined unit. The WKIDs for predefined linear and angular units are listed here: esriSRUnit2Type, esriSRUnitType.
The Unit returned is often used in other Geometry service methods such as Buffer.
IGeometryServer.FindUnitsByWKT Method
Defines a unit object based upon its well known text string.
Public Function FindUnitsByWKT ( _
ByVal wkt As String _
) As IUnit
public IUnit FindUnitsByWKT (
string wkt
);
Remarks
Finds a predefined linear or angular unit of measure based on its well known text string (WKT). The Unit returned is often used in other Geometry service methods such as Buffer.
Here are some examples of WKT strings for linear and angular units.
U.S. Survey Foot:
UNIT["Foot_US",0.3048006096012192,AUTHORITY["EPSG",9003]]
Arc-minute:
UNIT["Minute",0.0002908882086657216,AUTHORITY["EPSG",9103]]
Creating custom units
You can create a custom unit in ArcObjects by using the ImportFromESRISpatialReference method on an existing linear or angular unit object. Web service clients can do this by creating a LinearUnit or AngularUnit value first and then assigning the WKT string to the WKT property of the value. The example script in this topic illustrates the former approach and the example provided in the IGeometryServer topic illustrates the latter.
IGeometryServer.GetAreasAndLengths Method
Calculates areas and perimeter lengths for each polygon in the specified array.
Public Sub GetAreasAndLengths ( _
ByVal pSR As ISpatialReference, _
ByVal pInPolygons As IPolygonArray, _
ByRef ppAreas As IDoubleArray, _
ByRef ppLengths As IDoubleArray _
)
public void GetAreasAndLengths (
ISpatialReference pSR,
IPolygonArray pInPolygons,
ref IDoubleArray ppAreas,
ref IDoubleArray ppLengths
);
Remarks
All geometries are assumed to be defined in the spatial reference pSR, which cannot be nil. The area and length values are computed in that spatial reference. It is not recommended that this method be used on geometries associated with a geographic coordinate system, since the length would then be calculated in units of "degrees" and the area would be calculated in units of "square degrees".
Refer to IGeometryServer for additional details on how the input spatial reference is interpreted.
IGeometryServer.GetLabelPoints Method
Calculates an interior point for each polygon.
Public Function GetLabelPoints ( _
ByVal pSR As ISpatialReference, _
ByVal pInPolygons As IPolygonArray _
) As IPointArray
public IPointArray GetLabelPoints (
ISpatialReference pSR,
IPolygonArray pInPolygons
);
Remarks
Generates one point geometry per input polygon. Each point is guaranteed to be inside its corresponding polygon. The ArcObjects IArea::LabelPoint property is used to generate the output points. All input geometries are assumed to be defined in the input spatial reference pSR. pSR cannot be nil.
IGeometryServer.GetLengths Method
Calculates the length of eacch polyline in the specified array.
Public Function GetLengths ( _
ByVal pSR As ISpatialReference, _
ByVal pInPolylines As IPolylineArray _
) As IDoubleArray
public IDoubleArray GetLengths (
ISpatialReference pSR,
IPolylineArray pInPolylines
);
Remarks
All geometries are assumed to be defined in the spatial reference pSR, which cannot be nil. The length values are computed in that spatial reference. It is not recommended that this method be used on geometries associated with a geographic coordinate system, since the length would then be calculated in units of "degrees". You can use the GetLengthsGeodesic method to compute accurate lengths for polylines with latitude-longitude coordinates.
Refer to IGeometryServer for additional details on how the input spatial reference is interpreted.
IGeometryServer.Project Method
Projects an array of geometries from their current spatial reference (pInSR) to a destination spatial reference (pOutSR). The projection process can optionally include a datum transformation if the source and destination SRs have different GCSs.
Public Function Project ( _
ByVal pInSR As ISpatialReference, _
ByVal pOutSR As ISpatialReference, _
ByVal xFormDir As esriTransformDirection, _
ByVal pXForm As ITransformation, _
ByVal pExtent As IEnvelope, _
ByVal pInGeometries As IGeometryArray _
) As IGeometryArray
public IGeometryArray Project (
ISpatialReference pInSR,
ISpatialReference pOutSR,
esriTransformDirection xFormDir,
ITransformation pXForm,
IEnvelope pExtent,
IGeometryArray pInGeometries
);
Remarks
The Project method applies the projection pOutSR to a copy of each element of pInGeometries and places the results in ppProjectedGeometries. All input geometries are assumed to be in the spatial reference pInSR, which cannot be nil. The input geometries are not modified. The array can contain mixed top-level geometry types (specifically points, multipoints, polylines and polygons). The array can also contain envelopes. pXForm and pExtent are optional. If pXForm is specified, then it is an instance of a GeoTransformation subclass (see EDN for details on datum transformations), and xFormDir must also be specified (esriTransformForward
, esriTransformReverse
). If pExtent is specified, then all input geometries are then assumed to be contained in it, and an attempt will be made to optimize the projection operation by checking if that extent is completely contained in the projection's horizon.
The SpatialReference property for all returned geometries will be null. It is the consumers responsibility to assign the spatial reference to each geometry returned, if desired. In this case, the spatial reference is assumed to be the output spatial reference defined for the Project operation.
If pXForm is not specified and the datums of the specified spatial references are not the same, then a search is made through a set of default datum transformations (a.k.a geographic transformations) . Currently, the following transformations, identified by name and WKID, are in that set:� esriSRGeoTransformation_NAD_1927_TO_NAD_1983_NADCON
, forward and reverse, WKID = 1241� esriSRGeoTransformation_NAD1983_To_WGS1984_1
, forward and reverse, WKID = 1170� esriSRGeoTransformation_NAD1927_To_WGS1984_4
, forward and reverse, WKID = 1173
Refer to FindSRByWKID for a discussion on how to create the different kinds of spatial reference systems that can be used with this method. In addition, Well Known Identifiers (WKIDs) for available geotransformations are listed in the following enumerations:
esriSRGeoTransformation2TypeesriSRGeoTransformation3TypeesriSRGeoTransformationType
Refer to GeometryServer for additional details on how the input spatial reference is interpreted.
IGeometryServer.Relation Method
Determines the pairs of geometries from the input geometry arrays that participate in the specified spatial relation.
Public Function Relation ( _
ByVal pSR As ISpatialReference, _
ByVal pInGA1 As IGeometryArray, _
ByVal pInGA2 As IGeometryArray, _
ByVal r As esriSpatialRelationEnum, _
ByVal param As String _
) As IRelationResultArray
public IRelationResultArray Relation (
ISpatialReference pSR,
IGeometryArray pInGA1,
IGeometryArray pInGA2,
esriSpatialRelationEnum r,
string param
);
Remarks
Computes the set of pairs of geometries from pInGA1 and pInGA2 that belong to the specified relation. Both arrays are assumed to be in the coordinate system pSR, which cannot be nil. The relations are evaluated in 2D. Z coordinates are not used. Geometry types cannot be mixed within an array. Further restrictions on the types of geometries in an array are listed in the following table. r is a member of esriSpatialRelationEnum and can be one of the following:
Name | Description |
---|---|
esriSpatialRelationDisjoint | Same as IRelationalOperator::Disjoint. The zero-based index of a geometry from pInGA1 and the zero-based index of a geometry from pInGA2 define an element of the output array of relation results if the geometries share no points in common. See IRelationalOperator_Disjoint for some examples of the disjoint relation. There are no additional restrictions on the types of geometries in the input arrays. |
esriSpatialRelationIntersection | The opposite of esriSpatialRelationDisjoint. An element of the output array will specify the indexes of geometries from the input arrays if they share at least one point in the xy plane. There are no additional restrictions on the types of geometries in the input arrays. |
esriSpatialRelationInteriorIntersection | Same as esriSpatialRelationIntersection, but excludes intersections that occur only at boundaries (two touching polygons for example). The interior of a point is considered to be the point itself and the interior of a polyline excludes the endpoints of all its parts. There are no additional restrictions on the types of geometries in the input arrays. |
esriSpatialRelationIn, esriSpatialRelationWithin | These relations are similar. esriSpatialRelationIn is the same as IRelationalOperator::Within. esriSpatialRelationWithin is the same but also allows polylines that are strictly on the boundaries of polygons to be considered “in” the polygon. This case is disallowed by the former relation (and disallowed by IRelationalOperator::Within). The dimension of all geometries in pInGA1 must be >= the dimension of geometries in pInGA2. |
esriSpatialRelationPointTouch, esriSpatialRelationLineTouch, esriSpatialRelationTouch | esriSpatialRelationPointTouch and esriSpatialRelationLineTouch are boundary intersections classified by dimension of intersection. esriSpatialRelationTouch is the union of those two and is equivalent to the ArcObjects IRelationalOperator Touch method.These relations are defined for polylines and polygons. |
esriSpatialRelationLineCoincidence | The boundaries of the shapes must share a 1D intersection, but the relationship between the interiors of the shapes is not considered (they could overlap, one could be contained in the other, or their interiors could be disjoint). This relation applies to polylines and polygons. |
esriSpatialRelationCross | Same as the ArcObjects IRelationalOperator::Cross method. Lines can cross other lines at a point and lines can cross polygons. See IRelationalOperator_Crosses for examples. |
esriSpatialRelationRelation | 'param' defines the 'Shape Comparison Language' string to be evaluated. Strings such as "RELATE(G1, G2, ""FFFTTT***"")" are accepted, in addition to other kinds of strings. See the following EDN topic for more details on the Shape Comparison Language. http://edndoc.esri.com/arcobjects/9.2/NET/40de6491-9b2d-440d-848b-2609efcd46b1.htm |
The output array contains elements of type
struct esriRelationPair
{
// The index of the left element in the relation.
long m_leftIndex;
//The index of the right element in the relation.
long m_rightIndex;
} esriRelationPair;
mleftIndex is a zero-based index into _pInGA1 and mrightIndex is an index into _pInGA2.
esriGeometryRelationEnum is a synonym for esriSpatialRelationEnum. The former is the type name exposed through the web service. The latter is exposed through the COM api.
Refer to IGeometryServer for additional details on how the input spatial reference is interpreted.
IGeometryServer.Simplify Method
Applies the ArcObjects 'Simplify' operation to each element of the geometry array.
Public Function Simplify ( _
ByVal pSR As ISpatialReference, _
ByVal pInGeometries As IGeometryArray _
) As IGeometryArray
public IGeometryArray Simplify (
ISpatialReference pSR,
IGeometryArray pInGeometries
);
Remarks
Applies the ArcObjects geometric simplification operation to a copy of each geometry in the input array, placing the result in ppSimplifiedGeometries. The input geometries are assumed to be specified in the input spatial reference pSR, which cannot be nil. The elements can be a mixture of points, multipoints, polylines or polygons. Elements that can’t be simplifed are replaced with empty geometries of the same type at the corresponding index entry in the output array.
Refer to IGeometryServer for additional details on how the input spatial reference is interpreted.
This operation uses the coordinate grid and the xy and z cluster tolerances of the spatial reference. For more information on these properties and how they can affect your coordinates, please refer to the ESRI whitepaper “Understanding Coordinate Management in the Geodatabase”: http://support.esri.com/index.cfm?fa=knowledgebase.whitepapers.viewPaper&PID=43&MetaID=1301
Simplify alters the input geometry making its definition "topologically legal" with respect to its geometry type:
- For Points, Simplify does nothing. A point has no constraints on the values of its coordinates.
- For Multipoints, Simplify snaps all X, Y, Z, and M coordinates to the grid of the associated spatial reference (defined by the spatial reference’s false origin and xyUnits), then removes identical points. A point is identical to another point when the two have identical X and Y coordinates (after snapping), and when attributes for which it is aware are identical to the attributes for which the other point is aware. For example, if both points are Z aware, the Z coordinate values must be identical.
- Polylines are simplified using the SimplifyNetwork method. Coordinates are snapped, zero-length segments and empty parts are removed. Length is determined in 3D if the polyline has z coordinates, otherwise it is determined in 2D.
- For Polygons, Simplify identifies an interior and exterior for the polygon, then modifies the polygon structure to be consistent with that determination. The methodology for identifying interior and exterior is:1. Remove all dangles2. Identify the largest legal rings, add them to the output version of the polygon, then delete them from the working version3. RepeatThis operation uses the xy cluster tolerance of the associated spatial reference to determine when two vertices are the same, or when a vertex needs to be snapped to a line. This specific approach is subject to change in future releases of esri software. At the end of Simplify, no rings will overlap, no self intersection will occur (except in certain circumstances) and, in general, an arbitrary point can always be classified unambiguously as either outside, on the boundary of, or inside the polygon. All exterior rings are oriented clockwise. All interior rings (i.e. holes) are counter-clockwise.
Classes that implement IGeometryServer
Classes | Description |
---|---|
GeometryServer (esriGeoDatabase) | Provides access to standard operations on geometric 'value' objects. The input geometries are never modified by these operations. Designed for use in building web services and web applications. |
GeometryServerImpl | Provides access to standard operations on geometric 'value' objects. The input geometries are never modified by these operations. Designed for use in building web services or other kinds of distributed applications. |
Remarks
The GeometryServer lets clients programmatically apply common geometric operations to arrays of geometry 'value' objects. Buffering, projection of geometries from one spatial reference system to another, and evaluation of spatial relations are some of the operations provided.
For on overview of this interface, please refer to the documentation for the GeometryServer object defined in the geodatabase object library (esriGeodatabase).