IElementSet

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org.openmi.standard
Interface IElementSet

public interface IElementSet

Data exchange between components in OpenMI is always related to one or more elements in a space, either geo-referenced or not. An element set in OpenMI can be anything from a one-dimensional array of points, line segments, poly lines or polygons, through to an array of three-dimensional volumes. As a special case, a cloud of IDBased elements (without co-ordinates) is also supported thus allowing exchange of arbitrary data that is not related to space in any way.

The IElementSet interface has been defined to describe, in a finite element sense, the space where the values apply, while preserving a course granularity level of the interface.

Conceptually, IElementSet is composed of an ordered list of elements having a common type. The geometry of each element can be described by an ordered list of vertices. The shape of three-dimensional elements (i.e. volumes or polyhedrons) can be queried by face. If the element set is geo-referenced (i.e. the SpatialReference is not Null), co-ordinates (X,Y,Z) can be obtained for each vertex of an element. The ElementType is an enumeration, listed in Table 1. Data not related to spatial representation can be described by composing an element set containing one (or more) IDBased elements, without any geo-reference.

Note that IElementSet can be used to query the geometric description of a model schematization, but an implementation does not necessarily provide all topological knowledge on inter-element connections.

The interface of a spatial reference (ISpatialReference) only contains a String ID. No other properties and methods have been defined, as the OpenGIS SpatialReferenceSystem specification (OGC 2002) provides an excellent standard for this purpose.

The element set and the element are identified by a String ID. The ID is intended to be useful in terms of an end user. This is particularly useful for configuration as well as for providing specific logging information. However, the properties of an element (its vertices and/or faces) are obtained using an integer index (elementIndex, faceIndex and vertexIndex). This functionality is introduced because an element set is basically an ordered list of elements, an element may have faces and an element (or a face) is an ordered list of vertices. The integer index indicates the location of the element/vertex in the array list.

While most models encapsulate static element sets, some advanced models might contain dynamic elements (e.g. waves). A version number has been introduced to enable tracking of changes over time. If the version changes, the element set might need to be queried again during the computation process.

Nested Class Summary
`static class`	`IElementSet.ElementType` Shape Type of an Elementset.

Method Summary
`java.lang.String`	`getDescription()` Additional descriptive information
`int`	`getElementCount()` Number of elements in the ElementSet
`java.lang.String`	`getElementID(int elementIndex)` Returns ID of 'ElementIndex'-th element in the ElementSet.
`int`	`getElementIndex(java.lang.String elementID)` Index of element 'ElementID' in the elementset.
`IElementSet.ElementType`	`getElementType()` ElementType of the elementset.
`int`	`getFaceCount(int elementIndex)` Returns the number of faces in an element.
`int[]`	`getFaceVertexIndices(int elementIndex, int faceIndex)` Gives an array with the vertex indices for a face.
`java.lang.String`	`getID()` Identification String EXAMPLE: "River Branch 34", "Node 34"
`ISpatialReference`	`getSpatialReference()` The SpatialReference defines the spatial reference to be used in association with the coordinates in the ElementSet.
`int`	`getVersion()` The current version number for the populated ElementSet.
`int`	`getVertexCount(int elementIndex)` Number of vertices for the element specified by the elementIndex.
`double`	`getXCoordinate(int elementIndex, int vertexIndex)` X-coord for the vertex with VertexIndex of the element with ElementIndex.
`double`	`getYCoordinate(int elementIndex, int vertexIndex)` Y-coord for the vertex with VertexIndex of the element with ElementIndex.
`double`	`getZCoordinate(int elementIndex, int vertexIndex)` Z-coord for the vertex with VertexIndex of the element with ElementIndex.

Method Detail

getID

java.lang.String getID()

Identification String

EXAMPLE:

"River Branch 34", "Node 34"

getDescription

java.lang.String getDescription()

Additional descriptive information

getSpatialReference

ISpatialReference getSpatialReference()

The SpatialReference defines the spatial reference to be used in association with the coordinates in the ElementSet. For all ElementSet Types except ElementType.IDBased a spatial reference must be defined. For ElementSets of type ElementType.IDBased the SpatialReference property may be null.

EXAMPLE:

SpatialReference.ID = "WG84" or "Local coordinate system".

getElementType

IElementSet.ElementType getElementType()

ElementType of the elementset.

getElementCount

int getElementCount()

Number of elements in the ElementSet

getVersion

int getVersion()

The current version number for the populated ElementSet. The version must be incremented if anything inside the ElementSet is changed.

getElementIndex

int getElementIndex(java.lang.String elementID)

Index of element 'ElementID' in the elementset. Indexes start from zero. There are not restrictions to how elements are ordered.

Parameters:: elementID - Identification String for the element for which the element index is requested. If no element in the ElementSet has the specified elementID, an exception must be thrown. .

getElementID

java.lang.String getElementID(int elementIndex)

Returns ID of 'ElementIndex'-th element in the ElementSet. Indexes start from zero.

Parameters:: elementIndex - The element index for which the element ID is requested. If the element index is outside the range [0, number of elements -1], and exception must be thrown. .

getVertexCount

int getVertexCount(int elementIndex)

Number of vertices for the element specified by the elementIndex.

If the GetVertexCount()method is invoked for ElementSets of type ElementType.IDBased, an exception must be thrown.

Parameters:

elementIndex -

The element index for the element for which the number of vertices is requested.

If the element index is outside the range [0, number of elements -1], and exception must be thrown. .

Returns:

Number of vertices in element defined by the elementIndex.

getFaceCount

int getFaceCount(int elementIndex)

Returns the number of faces in an element.