[Qgis-user] GPS Points CRS and delete doubles

[Greg Troxel]

"L.W." <eaglelw at gmx.de> writes:

> after I had imported my points correctly ... over 300.000 points
>
> how to equalize / convert the CRS over all layers and have the same
> visual output?

qgis is set up to deal with data being in one CRS and displayed in
another.  It is normal to use a projected CRS (as you are, or UTM, or
some other national/regional plane coordinates) as the project CRS and
have data in WGS84 or some national datum.  Other than skipping
transforms in some cases and causing errors of about a meter due to
confusion about WGS84 being a datum ensemble (and your data if from a
phone is surely not good enough that you'd notice this, and there is not
problem from WGS84 to 3857), this works fine.

So just leave the project CRS as you had it, and use the WGS84 codepoint
for your data and it should work.

> I like CRS 3857 more because (OSM and Google) the map looks better at
> this CRS.

Sure.  all of the lat/lon CRS are awkward because there is distortion
since 1E-5 of latitude and 1E-5 of longitude are not the same distance.

> But the more important question for me is how to delete double points
> not only by coordinate but with use of the timestamp in the same table.

I wonder if what you really want is a DP simplification, and surely that
must be an option in qgis already.

  https://docs.qgis.org/3.16/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html#qgissimplifygeometries
  https://docs.qgis.org/3.16/en/docs/user_manual/working_with_vector/functions_list.html#simplify

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