Priority Allocation

Introduction

This tool allocates land uses to polygon features based on a spatial overlay of point data with land use classifications and a user specified nominated priority order for situations where more than one land use feature type falls within the same polygon. The result of the process is a land use polygon data set with no over-lapping polygons

Inputs

Open the tool (Tools → Walkability → Priority Allocation) and enter your parameters as shown in the image below (these are also explained underneath the image)

[Click to Enlarge]

[Click to Enlarge]

  • Name: Output name of the resulting polygon layer, which will contain land use polygons with the same classes as selected in the “Priority Order” parameter.
  • Neighbourhoods: Polygon spatial data set which will dictate the spatial extent for which .
  • Land Use Lookup: A tabular data set containing attributes to reclassify the “Land Use Feature Points” to an aggregate schema.
  • Priority Attribute: A drop down list of attributes from the “Land Use Lookup” data set, which contain final classification to be allocated to the cadastral parcels and the output layer. This classification is usually a set of super classes, which are meaningful to examining walking.
  • Land Use Attribute: A drop down list of attributes from the “Land Use Lookup” data set, which contain feature type categories that match those contained in the “Land Use Feature Points”. This attribute must be named exactly the same and have the same data type (string or number) as the attribute in the “Land Use Feature Points” whcihc contains the feature types.
  • Parcels: A polygon data set which will constrain the areal extent to which land uses will be allocated from the “Land Use Feature Points”.
  • Land Use Feature Points: A point data set containing feature type category attribution.
  • Priority Order: A drop down list of distinct classes from the “Priority Attribute” can be selected one after the other in the order of highest priority first to lowest last to create a list of output land uses of interest.

Outputs

TBC

Additional Information

Background

Often there is a lack of detailed polygon land use data sets covering urban areas in Australia. Land use data can be supplemented with point data sets which contain information regarding the presence of built or natural features of interest that are analogous to land uses. As an example CBEH used the Western Australian Valuer General’s Office, Val Sys data base and developed a process to convert rateable features (as points) to areal land use cover (with cadastral parcels acting as areal units) via a point in polygon allocation process. An issue that this process overcomes is the likelihood that a number of point features with different land use classifications might fall in one cadastral parcel. CBEH used a priority nomination system, where users would dictate the order of the priority of allocation (e.g. If priority dictated that retail was more important residential, any cadastral parcel that had both retail and residential point feature falling in it would be classified retail).

Data Sources

In Western Australia the Valuer General’s Office hold a database of sold and/or rateable features, which the Local Government Authorities are charging rates on. These features are stored in the Val Sys database, for which Landgate is the custodian agency.

The features should contain attributes that identify their type, which can be used as a proxy for land use. In the Val Sys database there is an integer field (“Classification_Code”), which distinguishes the feature types very specifically (about 1000 types). This field can be used in conjunction with a look up table to help reclassify features to an analogous set of land use classifications, with which the features might be associated. In this case the land uses classes are based on a set Planning Land Use Categories (PLUCs) developed by the Department of Planning, Western Australia, and were extended to meet the needs of Centre for Built Environment and Health.

Analysis Process

This process was based on work undertaken at The University of Western Australia’s Centre for the Built Environment and Health at (CBEH) for the RESIDE study (Christian et al., 2011a), which used the Western Australian Valuer General’s Office, Val Sys data base and developed a process to convert rateable features (as points) to areal land use types (with cadastral parcels acting as areal units) via a point in polygon allocation process. Because more than one type of feature (e.g. a retail shop and a residential dwelling) could be contained within a single cadastral parcel, CBEH used a priority allocation process based on a priority nomination system. For example, if the priority dictated that retail was more important than residential, any cadastral parcel that had both a retail and a residential point feature falling in it would be classified as retail