New answers tagged topology
Shapefiles do not support topology directly, as you have discovered. The data must first be imported in to a geodatabase, and specifically a feature dataset within that geodatabase. If you need to continue on in shapefile form, you'll have to export it back out once you're done topology checking and editing. The answer to the actual/original question is ...
Hypsography deals with the peak hights or one can say spot heights which we derive hights after completion of top maps
JTS is only for cartesian coordinates, your's are ellipsoidal. So I would say the answer is "do not use JTS for this". You would need write a method for the calculation yourself.
As per my comment in that question, it's to do with the spTransform. Simply remove the offending line: world <- spTransform(world, CRS("+proj=robin"))
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