Orienteering Map Production: Processes, Purposes & Limitations

1. Unit 3 – Map Production Unit purpose: To outline the options and relevant processes in making an orienteering map, and to discuss an orienteering map’s purposes and limitations Learning outcomes: The level 2 controller will be able to organise the production of a map, including overprinted courses, in time to be used for a Group A2 or Group B event Content • Processes involved in map production • Digital versus offset printing • Principles of orienteering mapping, a fair test of orienteering skill • Limitations • Using computer-aided drafting (OCAD) • Using GPS • Producing course overprints C2 course, Unit 3, Map production

2. Map production - 1 Maps are rarely created from scratch by ground survey. Base maps are generally obtained from photogrammetric (PG) plots. Frequently old orienteering maps form the base map. Old orienteering maps: • Only as good as the quality of the previous map, distortions can be carried over and quite large errors very difficult to spot. • Multiple interpretations of feature size / significance over time C2 course, Unit 3, Map production

3. Map production - 2 PG plots: • Poor in heavy forest as heights are estimated from tree tops so deep valleys are underestimated as trees tend to grow higher to get light. • Good delineation of large linear features, smaller ones (especially in forest) will be missed. • May have minor contour features that do not reflect real or useable features on the ground. Survey: • Ground survey using the base map, then transferred to the final map, usually on OCAD. C2 course, Unit 3, Map production

4. Principles of orienteering mapping - 1 The map should depict the terrain in such a way that the competitor can read the map to allow them to accurately navigate, make fair route choices and find the control at the end of the leg. Maps should be surveyed at 1:7,500 to give a final scale of 1:15,000 and if 1:10,000 maps are required these should be a blown up 1:15,000 map. ISOM 2000 defines how and what should go onto the map, but the mapper interprets the ground. C2 course, Unit 3, Map production

5. Principles of orienteering mapping - 2 The controller needs to check the map carefully, especially with respect to consistency in mapping of point features and in mapping of runnability screens. Also that all required features (e.g. scale bar, north lines, legend for defined features like X). Controller and planner should agree map corrections before they go to the mapper for putting onto the map. Map printing: Careful monitoring is key to quality, ideally the planner or controller should be present during the print run. C2 course, Unit 3, Map production

6. Limitations of maps Features are depicted by symbols and frequently cannot be shown at true scale. The physical size of these symbols on the map can (and in complex areas will) limit the amount of detail that can be mapped. Consistency is the key, especially for point features. The more detailed a map is the more likely it is to be out of date. If all of the fallen trees or termite mounds are mapped then one new one will make the map inaccurate. Changes in vegetation that aren’t on the map can significantly affect runnability and lead to unfair decisions on route choice. Control sites should never have a map correction in the circle. C2 course, Unit 3, Map production

7. Using OCAD - 1 Advantages over drawing / scribing: • Easy to review draft maps. • Correct symbol size – assuming the cartographer doesn’t change them. • Electronic files can easily be transferred to officials. • Can be used as a base map for planning software – OCAD 8, Condes, Corpse. • Easy to make last minute changes to maps. C2 course, Unit 3, Map production

8. Using OCAD - 2 Disadvantages: • Anyone with the software can “correct” the map. • Map scales –be wary of 1:10,000 maps as these may have symbol sizes of a 1:15,000 map and therefore the electronic scale may actually be 1:15,000 not 1:10,000. • Easy to make last minute changes to the map – often the perfectionist will delay printing, reducing the time for a controller’s checks. C2 course, Unit 3, Map production

9. GPS • Useful for checking surveys. • Establishing fixed points for photogrammetrist. • Not useable in dense forest. • Very good for street / park maps. (also useful for organisers as GPS units have a real time clock updated by satellite so you can check your clocks haven’t drifted during an event) C2 course, Unit 3, Map production

10. Digital versus off-set printing - 1 Litho off-set: • Sharper and clearer print than a digitally printed map. • Usually more than one plate (often 6 colour plates) plus overprint purple, so the map need register points to check print alignment. Printer registers on the edge of the paper then trims maps after printing. • Course overprints (transparent purple) printed last, so underlying colours show through the purple print. • Overprinting needs to be done before trimming as the register will not be perfect after trimming. • Cost depends on the number of plates, more courses = higher cost. • More than one printing stage, so must check every map for register, each colour being present. C2 course, Unit 3, Map production

11. Digital versus off-set printing - 2 Digital: • Poorer print quality, most obvious in areas with yellow screen combined with complex brown detail. • Colours can vary dramatically from machine to machine, trial prints should be approved by the controller. • Map printed together with course, no register issues and 1 step process so usually quicker. • Colour sequence determined in the software / print parameters, only the top colour is printed so underlying colours will not be printed. • Cost depends on the number of maps (sometimes with a low per course set-up cost), more maps = higher cost. • Laser printer quality better than ink/bubble jet, both are less colourfast than litho off-set. C2 course, Unit 3, Map production

12. Course overprints - 1 Printing onto litho off-set maps: • Different plates for every course, don’t forget the register points! • Can use one plate for all map corrections, crossing points, finish funnel (but NOT start) etc. • Difficult to check by the controller, do they visit the printer and check the plates? Proofs are expensive. • Can be prepared from output from course planning software, usually incorporating control descriptions. • You may get slight shifts in overprint, careful control site selection and unambiguous / accurate control descriptions can overcome some of these issues. C2 course, Unit 3, Map production

13. Course overprints - 2 Printing onto digital maps: • Single database of sites and descriptions so less margin for errors. • Easy to check by the controller, proofs are simple to produce. • Output from course planning software, usually incorporates control descriptions therefore easy to share draft courses with controller. • Manually check the course lengths are correct! Don’t forget the limitations of digital printing, control circle and line breaks are very important in order to show detail under lines. Be very careful with easy and moderate courses that lines between controls do not delete paths. It is possible to change the order in the print set-up so that black and/or brown and/or blue override purple but this can cause other problems. C2 course, Unit 3, Map production