thiessenPolygon

Description

This transformation first creates a Thiessen net from the input locations, then averages this over the region inside a polygon.

Input

inputVariable (data for point locations)

Option

distanceGeoDatum

Geo datum used to calculate the distances in meters between the points. To calculate distances efficiently and to pre-sort the input points in a grid the earth's curved surface should be transformed to a flat two-dimensional surface. When the input geometry is not in meters calculation of distances will be very slow and a search all is required when there is no exact match. When there is no region/country specific coordinate system available choose a utm zone that best fits with your output region. http://en.wikipedia.org/wiki/File:Utm-zones.jpg. eg. UTM55S for Victoria state in Australia. Only use zone number and N for northern hemisphere and S for southern hemisphere

Output

outputVariable (data for polygons)

Configuration example

<?xml version="1.0" encoding="UTF-8"?>
<transformationModule version="1.0" xmlns="http://www.wldelft.nl/fews" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.wldelft.nl/fews http://fews.wldelft.nl/schemas/version1.0/transformationModule.xsd">
	<!--rainfall-->
	<variable>
		<variableId>Rain_Gauge</variableId>
		<timeSeriesSet>
			<moduleInstanceId>ImportTelemetry</moduleInstanceId>
			<valueType>scalar</valueType>
			<parameterId>P.obs</parameterId>
			<locationSetId>precipitation</locationSetId>
			<timeSeriesType>external historical</timeSeriesType>
			<timeStep id="daily0930"/>
			<relativeViewPeriod unit="day" start="-10" end="0" startOverrulable="true"/>
			<readWriteMode>read only</readWriteMode>
		</timeSeriesSet>
	</variable>
	<variable>
		<variableId>Rain_Basin</variableId>
		<timeSeriesSet>
			<moduleInstanceId>HEC_HMS_Sittoung_Update_Pre</moduleInstanceId>
			<valueType>scalar</valueType>
			<parameterId>P.sim</parameterId>
			<locationSetId>SubBasin</locationSetId>
			<timeSeriesType>simulated historical</timeSeriesType>
			<timeStep id="daily0930"/>
			<relativeViewPeriod unit="day" start="-10" end="0" startOverrulable="true"/>
			<readWriteMode>add originals</readWriteMode>
			<!--<delay unit="minute" multiplier="30"/>-->
		</timeSeriesSet>
	</variable>
	<transformation id="SpatialInterpolation_Rain">
		<interpolationSpatial>
			<thiessenPolygon>
				<inputVariable>
					<variableId>Rain_Gauge</variableId>
				</inputVariable>
				<distanceGeoDatum>UTM46N</distanceGeoDatum>
				<outputVariable>
					<variableId>Rain_Basin</variableId>
				</outputVariable>
			</thiessenPolygon>
		</interpolationSpatial>
	</transformation>
</transformationModule>

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