IsoPoly4

Function IsoPoly4(filename: string; maxcost: single; nodenum: integer; Xlong1,Ylat1,Xlong2,Ylat2: double): integer;

IsoPoly4 calculates polygons, which shows which areas are closest to each center as defined in the NodeListSet function.

The result is saved to filename, which should include path and filename, but exclude extension.

The output format is determined by property GISformat.

The output file holds information on the id of the nearest node.

The function can use one or more nodes as a basis for the calculation of node cost. Nodenum specifies the number of nodes entered into the standard nodelist.

The best way to understand these parameters is to try rwnetdemo.exe, which makes it possible to see the result immediately.

Set maxcost = 0, unless:

1) You want to limit the generated polygons to a maximum distance, so that areas beyond doesn't get related to any center.

or

2) You have a very large network and want to reduce calculation time. Set maxcost to a value, that guarantees all areas are covered.

It is possible to define a bounding box for the generated polygons. If it doesn't cover at least all nodes in the nodelist, it is extended to do so. Specifying all 0's means it just covers the network.

See also property AddNodes and separate discussion.

Latitude/longitude coordinates are not really supported by this function, but only in rare situations will it actually affect the generated polygons.

Possible error codes: -10 -30 -40 -41 -43

Versions: Standard Pro

ActiveX / VCL / CLX component: RWcalc