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>