[Tagging] Accuracy of survey

Tom Pfeifer t.pfeifer at computer.org
Wed Dec 24 11:00:36 UTC 2014

Friedrich Volkmann wrote on 2014-12-23 23:59:

> There are no GPS traces for pipeline markes. There are traces for roads and
> paths only.

It was not clear if the OP indeed wants to map pipelines,
or was just quoting the pipeline expert for his opinion about
surveying methods. And if you walk/drive along the pipeline, you
could create a trace, and even repeat over time.

> These traces can bear a systematic error due to reflections
> (e.g. under a cliff).

Yes of course, and in an "urban canyon" our multi-trace bell curve would be
very flat due to the even larger amount of multipath reception
and the position noise it injects.

> Even if you collect plenty of GPS traces with no systematic error, these
> still cannot beat a theodolite triangulation.

I tend to agree on the practical side, although triangulation has error
sources too, and we haven't defined the scale of your experiment, and the
number of my traces, for the scientific comparison. ;-)

My main argument, if you read it in context, was that crowdsourcing
of traces from consumer-grade devices provides a significant statistical
advantage over a single trace of such, an effect that the pipeline expert
might not have been aware of.


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