MAPsport SERVICES

5 Atahu Grove, Lower Hutt, New Zealand Phone (04) 566 2645


FIXING EXISTING MAPS (written Aug 07)

To The Mapping Officer

Existing maps are the neglected assets of orienteering.

I used to work in computer software. New projects were the glamour jobs. Maintaining software - fixing bugs and making minor extensions - was seen as humdrum.

Maps are the same. Clubs commission photogrammetry and mapping for a new map which will be used at a major event. The club's best planners will set the courses. Meanwhile, month in, month out, old maps are used for club events, even OYs. This is where inexperienced planners learn their stuff. On maps full of errors! Do you wonder why its hard to get planners?

The errors may have many sources:

  • Things on the ground have changed.
  • Things were never right to start with.
  • Multiple fieldworkers had different interpretations.
  • Corrections were made piecemeal over time.
  • The map was made before 2000, when there were different specifications.
  • There is now a sprint specification for maps of 1:4-5000
  • The basemap was dodgy. There may not have BEEN a basemap.
  • The cartographer was inexperienced at using OCAD
  • The map was added to and the extensions don't exactly match
Volunteer planners hardly ever have enough time or experience to remap errors - we are lucky if bad areas are avoided for control sites! Clubs rarely have the processes to assess and manage corrections as they are produced. Is the remapper reliable or do we risk making things worse? The result is that maps "stand still" as the ground around them changes. Compared to rising expectations, they go backwards. Beginners assume problems are their own fault - it may be the maps!



RECOMMENDATION...

Ideally you would give your maps a "10,000km service" by a "qualified mechanic". I know that's unrealistic. What you can do though is identify your one map that has a combination of high orienteering attraction and low approval by experienced competitors. Decide to do something about it.

My work is increasingly revising existing maps. It's not just adding and deleting features and changing the vegetation. Often features are in the wrong relationship and you have to decide which one is to be trusted.

My methods go back to checking the block pattern and often distortion is evident. Whole groups of features may have to be squeezed and stretched. This in the computer before setting foot on the ground. A by-product is that the map is related to the NZ grid.

Only when you know the block boundaries are right is it worth doing fieldwork revision. Send me the OCAD file and a brief statement of what you see as the major problems, and I'll make some guesses about what a fixup might take. If you know the origin of the basemap, tell me that too.

This revision might be more valuable to your club health than a new map. New maps are used for major events benefitting members of other clubs!

Yours in orienteering,
5 Atahu Grove, Lower Hutt, NZ.
Phone +64-4-566 2645, or feel free to contact me at Major Events.