[Qgis-user] Diameter of buffers

[Jorge Gustavo Rocha]

Hi Herbert,


You are using a Mercator based projection to calculate distances [1]. It
was not designed for distance calculations.


Can you reproject to your own national/local projected coordinate
system? Compute the buffers using it and compare the results.


Regards,


Jorge


[1] https://en.wikipedia.org/wiki/Mercator_projection


Às 14:21 de 14/01/19, Herbert Faber escreveu:
> Dear all,
> When I put ring buffers arond dot objects, the diameter doesn't
> come out as I would expect.
>
> For instance, when I try to make ring buffer with a distance of 100
> meter and 25 segments around a dot object. The diameter of the buffer
> turns out to be approx 126 m when I measure it with the ruler tool.
>
> What am I doing wrong?
>
> I work with OSM Standard map in EPSG:3857 - WGS 84 / Pseudo-Mercator
> - projection and so are my shape files.
>
> Best regards,
> Herbert Faber 
>
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