4 replies to this topic

[rok]

I'm making a range map for Proteus anguinus using NaturalEarth vector for countries and a vector layer of the olm's range from the IUCN. The problem is that although both layers are in GCS_WGS_1984 coordinate system, they do not overlay perfectly (see below).



I reckon this is a common issue when working with data from different sources - some are more precise than others ... so what do you usually do in such cases? Manually edit one feature so it matches the other?

Edited by rok, 17 November 2010 - 02:24 PM.

[radek]

I got some good answers here. Might be of some help.

[David Medeiros]

Are the olm range data a subset of all nations displayed such that each nation in the subset is included in its entirety? As opposed to having the olm range cover portions of some nations?

If so than you could just duplicate the NE country layer, remove the nations not in the olm subset and re-classify or symbolize the new layer.

[frax]

Which of the layers do you find have the most accurate coast lines?

[jamesf]

If you're using ArcGIS, usually I identify one layer that's more accurate than the other layers. From there, I'll load everything into a geodatabase and define some topology rules that will assist me in snapping one layer to the other. (The advantage to the topology is you can browse through the errors and mass-select some of the easier fixes and auto-fix them.)