Interpolating this to get a surface (that is what listplot3d does, but listpointplot3d doesn't) is quite complicated and takes a lot of time with millions of points, i'm not sure if Mathematica will be able to handle it. Interpolating your data on a rectangular grid will make plotting this possible, i guess you don't really need 48 million datapoints to visualize your surface? right? i gues 10^4-10^5 should be enough to get an idea of what the data looks like...

Hi Malcolm,

is your data on a regular grid? if yes: no do no supply the x and y data per point, rather just give an array of heights, and then DataRange to set the x and y values. If you supply x,y,z triplets it will do so-called delaunay triangulation on all your point which is very slow...

--SH

With large amount of datapoints I found that importing it as binary files is the fastest, probably mainly because it can directly read it from the files and put it directly in the memory.

For using the dat files you can read it in many different ways:

Going from SemanticImport, to Import, to ReadList you go from slow, normal, to fast. But they have their differences with respect to robustness.

In the end it really depends also on WHAT you read. a 2.4GB file is quite hefty, but the data might be much smaller when stored binary...