[GRASS-user] Re: link to datasets from other locations?

Dylan Beaudette dylan.beaudette at gmail.com
Thu Jul 2 11:25:12 EDT 2009

On Thu, Jul 2, 2009 at 12:07 AM, Hamish<hamish_b at yahoo.com> wrote:
> 2c POV:
> *every* single GIS I have seen which does on-the-fly reprojection has had
> major problems which can present itself in a way which is not obvious
> to the user (typically due to mixed datums). Then the user happily goes
> along doing their work, publishing their reports, only sometimes
> realizing that something has misaligned internally. Or ugly non-solutions
> like rubber sheet dragging to visually correct the misalignment without
> considering the real cause become taught as the de facto method in the
> workflow. (easier than teaching about ellipsoids and datum math)
> I admit it's not the same as theoretically it could be done correctly,
> but I sort of class it with the common request for scalebars or 1:xx,xxx
> map scale for lat/lon cartography. It sounds like a good idea, and lots
> of other software give the users what they demand there, but that doesn't
> mean it's valid or a good idea. For map projections it is not invalid,
> just really really hard to get right (probably because "right" is often
> a very subjective answer in geodetics).
> Hamish

Yes. I am probably preaching to the choir here, but I have seen this
time and time again in both GIS classes, along with faculty, making
these type of basic (but not obvious) mistakes. Seems like a good
idea, but usually results in confusing and mysterious errors when
processing the data.


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