Topological Consistent Generalization of OpenStreetMap<br />By Padraig Corcoran, Peter Mooney, Adam Winstanley<br />NUI Ma...
Problem Specification<br />2<br />LBS Device<br />
Generalisation by Simplification<br />Remove vertices in a guided and simplified manner<br />3<br />
A simplification should be invariant with respect to certain properties.<br />In the context of LBS, shape, size and topol...
Topological Invariance<br />5<br />Simplification not <br />Topological Invariant<br />Original OSM Map<br />
The Research Question<br />Given a map and corresponding simplification, can we determine if the simplification is  topolo...
Any method for determining topological invariant may be summarized in terms of the followingconstraints :<br />constraints...
Topological features can be classified as planar or non-planar.<br />8<br />Planar Topology<br />Non-Planar Topology<br />
Planar topology analysis<br />An analysis of three methods for determining planar topology invariance were examined in ter...
Symbol * indicates that determining topological invariance not subject to any constraint.<br />Symbol x indicates that det...
Non-Planar topology analysis<br />We analysized the techniques Kulik et al. (2005) and Weihua(2008).<br />Constraints on t...
Shape and size invariants<br />To satisfy shape invariants the contour evolution technique of Latecki and Lakmper (1999) w...
We determine if removing a vertex will significantly reduce the representation of the polygons shape and in turn not maint...
Results<br />14<br />38 Vertices<br />182 Vertices<br />
15<br />375 Vertices<br />34 Vertices<br />
Conclusions / Future Work<br />For LBS reducing map data size is very important.<br />This reduction must be subject to ce...
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7B_2_Topological consistent generalization of openstreetmap

  1. 1. Topological Consistent Generalization of OpenStreetMap<br />By Padraig Corcoran, Peter Mooney, Adam Winstanley<br />NUI Maynooth, Ireland<br />1<br />
  2. 2. Problem Specification<br />2<br />LBS Device<br />
  3. 3. Generalisation by Simplification<br />Remove vertices in a guided and simplified manner<br />3<br />
  4. 4. A simplification should be invariant with respect to certain properties.<br />In the context of LBS, shape, size and topological invariants are particularly important.<br />Few techniques satisfy multiple invariants.<br />4<br />
  5. 5. Topological Invariance<br />5<br />Simplification not <br />Topological Invariant<br />Original OSM Map<br />
  6. 6. The Research Question<br />Given a map and corresponding simplification, can we determine if the simplification is topological consistent without constraints?<br />6<br />
  7. 7. Any method for determining topological invariant may be summarized in terms of the followingconstraints :<br />constraints on the types of topology for which the technique can determine consistency without returning a false-positive;<br />constraints on the types of topology for which the technique can determine consistency without returning a false-negative;<br />constraints on the types of simplification to which the technique can be applied.<br />7<br />
  8. 8. Topological features can be classified as planar or non-planar.<br />8<br />Planar Topology<br />Non-Planar Topology<br />
  9. 9. Planar topology analysis<br />An analysis of three methods for determining planar topology invariance were examined in terms of their corresponds constrains:<br />De Berg et al. (1998) strategy;<br />Saalfeld (1999) strategy;<br />da Silva and Wu (2006) stragegy.<br />9<br />
  10. 10. Symbol * indicates that determining topological invariance not subject to any constraint.<br />Symbol x indicates that determining topological invariance is subject to constraints.<br />10<br />
  11. 11. Non-Planar topology analysis<br />We analysized the techniques Kulik et al. (2005) and Weihua(2008).<br />Constraints on the forms of simplifications to which they can be applied.<br />11<br />Simplification<br />Original Features<br />
  12. 12. Shape and size invariants<br />To satisfy shape invariants the contour evolution technique of Latecki and Lakmper (1999) was used.<br />Satisfy size invariants presented a challenge.<br />12<br />
  13. 13. We determine if removing a vertex will significantly reduce the representation of the polygons shape and in turn not maintain size invariance.<br />13<br />
  14. 14. Results<br />14<br />38 Vertices<br />182 Vertices<br />
  15. 15. 15<br />375 Vertices<br />34 Vertices<br />
  16. 16. Conclusions / Future Work<br />For LBS reducing map data size is very important.<br />This reduction must be subject to certain invariants.<br />Results on OSM data show this can be achieved.<br />Future work<br />Simplify all linear features.<br />Progressive transmission of maps for LBS.<br />16<br />

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