Simplified Geographical Information System


An MS Excel spreadsheet for working with geographical data. Map references from the adelaide UBD street directory are converted to Australian Map Grid (AMG) references, and then Acad Lt script generated so that can be plotted in Acad.

The example has grid coordinates of shed suppliers (A table was manually created using online yellow pages information, a while back). The points are plotted on an xy-chart, and the centroid of the group is calculated and also plotted.

There is a vba macro which scans all the coordinates and generates a table of nodes, from which Acad script is generated in the worksheet using worksheet formulae. The macro scans the coordinates and determines if two suppliers are within 5 km radius of one another, if they are then a line is drawn between them. A simple approach to central place theory.

Any other  data could be used, for example location of:

  1. consulting engineers,
  2. supermarkets
  3. schools
  4. hospitals
  5. churches
  6. Projects

It can be further refined by using Delaunay triangulation. Other approaches are to insert shaded blocks at the point location (eg. red squares for high project count, cyan squares for low project count).

Approach taken is that if just need to work with some coordinate data, then don’t need a full blown GIS as most of the time an actual map is of no real value.