New answers tagged linear-referencing
I was able to get around this by editing my coordinate system to display in miles.
Create points at the ends of road SP-322. In double type field of the points set 0 for start point and road length for end point. Use points to calibrate roads into routes Create events along the road using your table, thus record in your table SP-322, 3555 (m) will become a point 3555 m from the start of road SP-322
I've written a function for PostGIS which uses linear referencing functions to redistribute vertices for [Multi]LineString and [Multi]Polygon geometries. For PostGIS 2.0 and earlier, ST_LineInterpolatePoint needs to be renamed to ST_Line_Interpolate_Point. CREATE OR REPLACE FUNCTION ST_RedistributeVertices(geom geometry, distance double precision) RETURNS ...
As I explained in Snap points to line and calculate chainage using Open source GIS the QGIS LRS plugin accepts points not lying on the line to calibrate it, so it's not a problem that your points are not on the line. By the way, I assume you already loaded the txt file as a point layer (say gps_layer). As you may have already read, you first need to ...
That's a very nice use case for Linear Referencing tools. Have a look at my answer to this post: QGIS Linear Referencing. There I explain the capabilities of the QGIS LRS plugin. That should help you get started.
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