I have output from a geophysical technique that produces X,Y,Z and scalar value for millions of points, which have been stitched together appropriately (by networkx if it matters) into multilinestringzm format, then inserted into a PostGIS DB by my own (homebrewed) geophysical code.
There is one multilinestring per Z value (roughly 10-20% of the ~12 million points all share the same Z values), and each of the 10 or so Z values and their corresponding multilinestringzm geometries are in a separate row of the table.
What I'd like to be able to do is color each point in a multilinestring according to its M value, but have been struggling for quite some time in how to accomplish this. (Even better would be to have a color gradient on the line segment between two points.)
I really need to have this work in QGIS (or ARCscene?) because there is a whole lot of other normal 2D GIS info to integrate. My earlier trials outputting my data in VTK format and using VisIt from LLNL to read both the VTK and GIS files, while successful, is too heavyweight to share with my colleagues in joint projects.
Any hints on how to color-by-m-value?