Pitney Bowes MapInfo Vertical Mapper - Manual (Page 62)

Understanding the Location Profiler Model
60
Vertical Mapper 3.7
The Cell Size box enables you to define the cell size in the native coordinate system units of the
map. The grid dimension (in cell units) varies inversely with cell size: the smaller the cell, the larger
the grid file. The value you choose should be a compromise between the degree of resolution
required for analysis, the processing time, and file size. The grid dimensions (in cell width and
height) and the grid file size (in kilobytes) are displayed and updated as the cell size is adjusted.
The Search Radius box enables you to define the maximum size of the circular zone centred on
each grid node that is used to select point locations. For each point location lying within this search
zone, the distance between the grid cell (the centre of the zone) and the point is measured. By
default, the search radius is set to select all points in the point table. If the point table is large, reduce
the number of grid calculations by increasing the cell size. Otherwise, decrease the search radius.
The Display Radius box enables you to define the size of the circular zone centred on each grid
node within which a point must lie in order for that grid cell to be assigned a value and be displayed.
This setting is used to control the extent of grid creation in areas of the map that do not contain data,
such as the outer margins of the map area.
The Units field displays the unit of horizontal distance measurement used in the model calculation
(cell size, search radius, and display radius). If the point table is set to a Latitude/Longitude
coordinate system, then the cell size unit is in degrees and you can select and set the units for
Search Radius, Display Radius, and Exclusion Radius in kilometres, miles, metres, or feet from
the Unit list. All three parameters are updated instantly to the selected unit.
However, when applied to the Location Profiler model, all distance calculations are automatically
converted to arc lengths corrected for earth curvature (oblate spheroid model).
The Minimum # of Points box enables you to set a lower limit on the number of point locations that
must be found from each cell before a calculation is made. The default value is one.
The Maximum # of Points box enables you to set an upper limit on the number of point locations
measured from each grid cell. Used in combination with the search radius setting, the Location
Profiler model will stop searching for point locations once either setting has been maximized. The
default setting is the total number of points found in the table.