Setting Up in the Real World – GeoReferencing : Large Sites

Series Index - Setting Up in the Real World

In the case of linear infrastructure it is fairly obvious that each major facility along a route will have its own GCS. Other cases may be less clear cut. Take an airport.

This diagrammatic example (the runways are the length of London Heathrow) shows how buildings relating to a large campus are spaced out over the site in various orientations and relationships:

Overlay this with the OpenBuildings Designer (OBD) 4.26km Solids Working Area (SWA), then highlight the portion of the SWA that has positive coordinates and we can see that the preferred working area is relatively small relative to the whole campus. (Note positive coordinates define the preferred area just because this is convenient and less open to typographical errors than involving negative coordinates, there is no technological restriction involved.)

How then, should GCS's be defined for the various parts of the campus?

One approach might be to divide the campus up into sections that fit the preferred working area discussed above: 

However that is letting the software drive the process. Several other factors may be more relevant.

  • For instance, how is design and construction phased and let? There may be immediately obvious divisions from that aspect of process that naturally generate a logical GCS arrangement.
  • There could be organisational divisions for future facilities management or site operations that would also drive the GCS logic.
  • One option is simply to have a GCS for every individual major building. That might seem over complex at first glance, but does have the potentially significant benefit that each building can be independently arranged on the site without needing to relocate any of the geometry within each building model. If a building moves during design, simply update the GCS transform for that building and it is relocated on the site.

There are no hard and fast rules but hopefully these examples will have offered some guidance.