Change Requests | OGC

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Open Geospatial Consortium

OGC Doc 08-160

CR-Form-v3

CHANGE REQUEST



_{GML 3.2.1 CR ?}

 rev

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 Current version: 3.2.1 

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Proposed change affects:  AS Imp Spec Recom. Paper Other X

Title:  Simple efficient encoding of GM_MultiPoint

Source:  Andrew Woolf (Natural Environment Research Council)

Work item code:  Date:  2009-05-13

Category:  B

Use one of the following categories: F (Critical correction)

A (corresponds to a correction in an earlier release)

B (Addition of feature),

C (Functional modification of feature) D (Editorial modification)

Detailed explanations of the above categories can be found in the TC Policies and Procedures.

Reason for change:  Encoding of the ISO 19107 GM_MultiPoint class in GML (gml:MultiPoint) allows only a series of gml:Point objects. This can lead to inefficiencies where a large number of GM_Points are involved.. This CR provides an alternative efficient encoding for cases where the identity of points within the aggregate is not of interest. The encoding follows GM_MultiPoint’s derived attribute ‘position’ which is a set of DirectPositions in ISO 19107.

Summary of change:  Define additional simple GML encoding of GM_MultiPoint.

Consequences if 

not approved: No support for efficient encodings of GM_MultiPoint where identities of member points is not of interest.

Clauses affected: 

Other specs  Other core specifications 

Affected: Abstract specifications

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The OGC Technical Committee Policies & Procedures 05-020r3

</extension> </complexContent> </complexType>

gml:SimpleMultiPoint implements, and provides a simplified encoding for, ISO 19107 GM_MultiPoint (see ISO 19107:2003, 6.5.4). A gml:SimpleMultiPoint consists of a list of DirectPositions.

11.3.2.2 MultiPointPropertyType, multiPointProperty

A property that has a collection of points as its value domain may either be an appropriate geometry element encapsulated in an element of this type or an XLink reference to a remote geometry element (where remote includes geometry elements located elsewhere in the same document). Either the reference or the contained element shall be given, but neither both nor none.

This property element either references a point aggregate via the XLink-attributes or contains the "multi point" element. gml:multiPointProperty is the predefined property, which may be used by GML application schemas whenever a GML feature has a property with a value that is substitutable for gml:MultiPoint or gml:SimpleMultiPoint.