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1

Let's assume we have the following layers "borders" (line) and "ocean" (polygon), see image below. With the following geoalgorithm Vector > Geoprocessing Tools > Difference..., it is possible to delete edges of the polygons that border the ocean. The output new "borders" layer will look as following Keep on mind that this object is a MULTILINESTRING....


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while inserting data in table you can have two check 1)You can create a buffer (st_buffer) around your road network and check if point intersects (st_intersects) your buffered area. 2) The distance between last recorded gps coordinates of that point and new gps coordinates is not more than 100m (ST_DISTANCE). Only then you insert that record in you DB. ...


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I have implemented such algorithm in Java using JTS. Here is the source code: https://github.com/jgaffuri/OpenCarto/blob/gh-pages/src/main/java/org/opencarto/algo/line/GaussianLineSmoothing.java The main steps are the following: Densify the input line with additional vertices along each segment. Prepare gaussian coefficients. Compute the position of the ...


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Other than with expressions, you can use the line-width-assistant - it's probably easier because you don't need expressions (but you can, if you want, see below). Select the assistent, select the source ( field that contains the values/width-information in your attribute table), than update values (that automatically selects min./max. values - otherwise ...


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That's quite easy: use pixel, points or mm as units for the width of the line (road, river) - thus a unit that refers to your rendered image/screen and not to the real world. Like this, you have the "Google-maps-effect" you refer to: your line is rendered always in the same width on your screen, whatever scale you zoom to. However, if you want to have "real-...


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