In fact i am asking for the method and the data needed for determining school catchment area.Example is http://www.qgso.qld.gov.au/maps/edmap/.

Probable Prerequisites:

  1. Catchment boundary must not cross buildings and should follow transport network.
  2. There not be any un-allocated area (void) i.e. area is not under any catchment.
  3. I need some sort of automation at most extent.

Overview-- see below


When zoomed in a bit more-- see below


N.B. I think Example website related one can give elaborate answer.

  • 1
    Have you got a proper transport network and parcels layer covering your study area (and/or building footprint layer in association with parcels)?
    – fatih_dur
    Aug 8 '15 at 3:06
  • Yes i have all the layers. I need the process as your help.
    – SAZ
    Aug 8 '15 at 6:29

I will assume these catchments are determined by taking into account minimum friction on the transport network, which is generally the travel time and you have ArcGIS Network Analyst extension. The brief process that I can advise as follows:

  • First you need to register an origin for each parcels, namely if there is a building this is going to be the source, otherwise parcel's itself. For this use Select by Location to find parcels intersecting with your buildings and then invert your selection. These are the parcels without buildings (I am assuming these layers are topologically correct);
  • By using Merge tool, merge buildings with these parcels. They will be your origins/incident-locations;
  • Use Spatial Join tool to join merged output of the previous step with parcels which will allow you to delineate catchment boundaries that do not transverse buildings. Parcels will be the target features;
  • Run Closest Facility Analysis tool from Network Analyst extension by picking facilities as schools layer and incidents as merged buildings-parcels layer;
  • Then join the output of Spatial Join with Routes layer of Closest Facility Analysis (FIDs of Merged output to Incident ID);
  • Finally you can Dissolve the joined layer in the previous step by using FacilitiesID field as the Dissolve field.

Most probably you need to find a way as crossing over the roads to have a seamless output of catchments, which is a little bit tricky. You can separate road parcels into smaller parts (say using fishnet analysis) and process them as origins/incidents like merged buildings-parcels. Alternatively you can adopt an approach as advised here to divide your roads from their centrelines and process them again as incidents.

  • Amazing!! I am test-driving, later i will inform you Samaritan!
    – SAZ
    Aug 11 '15 at 4:44
  • my try in brief- get center of property>use closest facility analysis where schools are destination and property-centers are source>Route layer>spatial join(by radius search)--but it generates overlapped area??
    – SAZ
    Sep 3 '15 at 7:13

I would suggest a raster-based cost allocation method of creating catchment areas.

The output might look something like this:

enter image description here

You would require a cost surface, which when creating the cost surface, would allow you to accomodate all the input parameters you specified above:

  • buildings as a separate layer should be burned into your cost surface at a much higher cost so that your catchments do not cross them
  • Rivers, as in the example you provided, should be burned into your cost surface at a much higher cost such that your catchments do not cross them and natural boundaries are formed along them
  • Roads can be burned in at a much lower cost such that they provide the basic travel network from which the catchments are calculated
  • All other areas would be have a low cost value also

Finally when you've got your cost surface and have run your cost allocation on your points, you can convert the output back to Vector for the mapping in the example above.

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