I am using the Load Builder and the Proportional Distribution by Area Method to compute the load from GIS Data. I have the Theissen Polygons created from a districts layer that have the flow data as well. Iam using the same layer to compute the flow. The problem is that the total flow calculated based on the Load Builder exceeds the total flow in the GIS layer itself calculated manually.
I have checked the coverage of the Theisen polygon; it is overlapping exactly with the flow layer. Any justification for this ?
Farah to add to Scott's response:
As seen in the screenshot and article from Scott the proportional distribution by area method is intended to use a flow boundary polygon layer which represents the area associated with a certain lump-sum demand, whereas the service area is different; it represents the area associated with the actual model junctions. This LoadBuilder method then distributes the flow polygon to the junctions based on how much of the area overlaps the service area polygon.
However I see that you mentioned you are using the same polygon shapefile for both the Service Area layer and the flow boundary. Typically you would use the Thiessen Polygon tool to generate the node service area layer, and then the flow polygon may be from your GIS or billing system with a field storing the lump-sum demand associated with the actual land/area (unrelated to the model junction locations)
If your shapefile contain polygons representing the area around each junction but you have the associated demand in each one, you can consider using the nearest node allocation method as LoadBuilder will compute the centroid of each polygon and assign it to the spatially nearest node in the model.
If this does not help, please provide a bit more information on the data that you have and what you are trying to accomplish, so that we can suggest the best approach to use in the OpenFlows products.
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.