[postgis-users] LinearReferencing: measure vertex of linestring?
pramsey at opengeo.org
Wed Mar 28 12:29:50 PDT 2012
Create a ticket describing the calibration, that's useful info and
would be a good utility for LRS users for a future version.
2012/3/28 Andrés Maneiro <amaneiro at icarto.es>:
> Hello people,
> I'm reviewing what postgis is able to do in terms of Linear Referencing. As
> fas as I could see, to calibrate a linestring there is only the method
> So, as stated in the example, the operation will create a route like:
> SELECT ST_AsEWKT(ST_AddMeasure(
> ST_GeomFromEWKT('LINESTRING(1 0, 2 0, 4 0)'),1,4)) As ewelev;
> LINESTRINGM(1 0 1,2 0 2,4 0 4)
> What I'm wondering is if somehow I could calibrate the vertex of the
> linestring, having as a result, for example, this route:
> LINESTRINGM(1 0 1,2 0 *1.7*,4 0 4)
> The project I'm working on is related to road management, and it's very
> common that the ratio between a route's length and its measures is not
> constant. So, my doubt goes: is it somehow possible to create a route in
> postgis where the measure and the distance are not directly related?
> (For those who know how ArcGIS "dynamic segmentation" works, what I'd like
> to achive is something similar to calibrate a route using points ).
> Let me know if I explain myself properly.
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