[Qgis-developer] distance measure feature isn't working correctly

[Martin Dobias]

On 7/30/07, Maciej Sieczka <tutey at o2.pl> wrote:
> Tim Sutton wrote:
> > Em 25/07/2007, às 03:57, Byambaa Mendbayar escreveu:
>
> >> I have feedback on distance measure tool in QGIS. It isn't working
> >> correctly; I mean it wasn't correct distance value on map. I have
> >> tested that issue on both on SVN Trunk (head) and Release-0_8_1
> >> branch. By the way I have old version of QGIS compiled by myself I
> >> didn't remember that version's revision. This old compiled version
> >> is working well for distance measuring and area measuring.
>
> I'm not sure if this is a bug or a new feature - in QGIS 0.8.1 and 0.9
> one *has to* "Enable the fly projection" for measuring tools to return
> expected values. Defining a projection for your project that suits the
> projection of your dataset is not enough. Could a knowledgable QGIS
> develepor explain?

AFAIK change of the behaviour was part of fixes by Magnus Homann who
added this way possibility to measure distances and areas in degrees.
In my original concept I've expected that when measuring, everyone is
interested in measuring only in real distances/areas e.g. in meters,
making the design simpler.

> Furthermore, I noticed a regression in 0.9 compared to 0.8.1 - you
> can't set units to meters or feet when working in lat/lon projection
> and to degrees for metric/feet system - through the interface that pops
> up after clicking the camera icon in the bottom-right. QGIS will always
> reset units to degrees for the former and to meters/feet in the latter
> case. However, you can manage the units fine if you do the same
> operation via Settings -> Project properies -> General. Strange.

I suggest to file a ticket for measure tool with ideas how it should
work in ideal world, what's needed there and what's not needed etc.
We'll try to fix current problems until the release of 0.9, if there
any ideas how to further improve measuring we can add them in some
future version since we're already in feature freeze.

Martin