Function IsoPoly1new(filename: string; node: integer; doughnut: boolean; convex: single): integer;
Obsolete function. Use Isopoly2 instead. Only reason to use this function is if you are working with large networks, large isochrones and have little RAM or patience.
IsoPoly1new calculates isocost polygons, which shows how far it is possible to go within a specified amount of cost from a node.
The result is saved to filename, which should include path and filename, but exclude extension.
The output format is determined by property GISformat.
Node specifies the start-node.
Use procedure StepsClear and StepsAdd to add a list of the actual isochrones generated.
Doughnut defines if the polygons are created as hollow polygons (doughnut) or not.
The best way to understand these parameters is to try rwnetdemo.exe, which makes it possible to adjust all parameters easily and see the result immediately.
Convex defines to what degree the polygons should be calculated as convex hulls. The area around the possible points are scanned to see if other points are further away from the start-node. If not, the point is included in the polygon. Convex is specified in terms of degrees, when scanning. If convex is 0, only points on the convex hull is included. If the polygon is small, you would usually use a high value (30), whereas large polygons should be created with a smaller value (2-3).
If convex<>0 degenerate polygons may be created in some rare situations.
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 -32 -37 -40 -43
Versions: Standard Pro
ActiveX / VCL / CLX component: RWcalc