[Qgis-user] degrees: is degr/min/sec still used? Or decimal preferable?

[Tobias Wendorff]

Hi there,

I had a similar discussion some days ago. It was not about deg/min,
about about precision. But the discussion isn't not that far away.

QGIS, GDAL and other tools are locked to IEEE 754 arithmetics.
I often had problems with this in the past, since only 14-15 digits
behind the dot/comma can be trusted at all.

So when using decimal degress with a higher resolution, you might
ran into problems. Better store them as string, like in good old Excel.

But also three digits make a problem. I've tried a QGIS plugin, which
shows the WKT output of the current geometry. Since I'm working in a
metric projection (UTM32N), I'm fine with three digits at millimeter
level. The plugin has thrown out crazy values with 15 digits:

Input geometry was 593024.302, plugin's output was 593024.30009235432
or anything like that. That's a no go for a GIS, which could be used
in cadastre offices :D

Best regards,
Tobias




Am Mo, 10.04.2017, 08:39 schrieb Richard Duivenvoorde:
> Hi List,
>
> Had a discussion here with some people about the use of showing the
> latlon degrees in degrees/minute/seconds tuple instead of the decimal
> notation:
> "4.40069397,51.71060887"
> vs
> "4°24?02.49807059?E,51°42?38.19184916?N" (or variations on that)
>
> Is there some general preference in this? To me the first one is just
> easier to handle, but I'm not sure what the general preference is in the
> GIS world.
>
> Any comments?
>
> Or is everybody using the national crs's anyway :-)
>
> Regards,
>
> Richard Duivenvoorde
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