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Sorry if this sounds too broad and opinion-soliciting...

I think the difference between Node and Vertex had been discussed before (for instance) Difference between node and vertex in GIS?, good and detailed discussions between renowned GIS leaders are open for us (me) to learn.

And my take is (sorry again if this is too simplistic... and I can be totally wrong...) "Vertex" is for location (xy) and "Node" includes its topology.

Is it still valid, given we now have 3D-GIS more closer than before? I mean; Vertex is the XYZ locator?

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To me a vertex can be a 2d or 3d coordinate. It's a mathematical point in space (2d or 3d) where lines meet. (Caveat: my background is Computer Science).

A "node" is an object in an object-oriented system (C++ in the case of QGIS and Qt). As such, it can have any information attached to it (as a control point in a bezier curve, x and y coordinates on the canvas, elevation etc.). It can also be part of a network (and have a degree etc.)

I'd say that a node is an abstraction of a vertex. A node might choose to ignore the z-value, in which case it is the same as a point in 2D. Or it might include it, in which case it's 3D.

I've written code to export gdal rasters to .obj files; Blender is very specific on what it means by a vertex - xyz :)

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