On 16 Jun 2008, at 19:17, Curt, WE7U wrote:
On Mon, 16 Jun 2008, Kristian Walsh wrote:
During development, we had considered xastir , but the need to re-
project all
mapping to UTM was a bit of a headache, so we did our own
visualisation
system.
Actually -> "unprojected" or "lat/long", but same idea. hi hi
:-)
Help monitor this new development and keep us honest WRT to map
projections, datums, etc. I'd love this to be genuinely useful in
the SAR field and for other emergency operations.
Me too. We were working on some statistical modelling (based on the
UK Centre for Search Research models) for missing persons. I'd like
to get that working in a more general visualisation system like xastir.
What we did was project the the vector data into the co-ordinate
system used by the raster mapping (in our case, Irish Grid). This
projection was only done for display: each recorded 'track' (in say,
WGS84 Lat/Lon) had a mirror 'projected track' whose points were in
the display projection (Irish Grid). Every time you convert from one
datum to another, you inevitably lose some accuracy.
Perhaps consider some of the Boost C++ libraries (www.boost.org):
they are
cross-platform and well supported.
Have only heard of the name. Will have to look at what that might
buy us.
There's a nice regular expression parser in there, as well as some
very clever serialisation and container classes. Some of the stuff
is "too clever by half", and it can throw up some of the most bizarre
compiler errors I've ever seen (so bad that the code has comments
like: "if you get a strange error on this line, you've left out a
'const'" ;-) )
The language hasn't moved much since the mid 80's. Apple have
recently
brought along an ObjectiveC 2.0, which adds garbage collection to
the mix.
The Objective-C runtime is the C runtime, with a couple of additional
runtime functions. All the things you hate about C are still there.
C++ is standardised, Objective-C is not.
The above pretty much blows it out of the water for me. Sounds like
C++ would be a better portable language for us than Obj-C. Thanks
for the info.
Does C++ have any standardized garbage collection?
No, unless you count std::auto_ptr< > as a garbage collected type. To
be honest, if you use the standard template library containers,
you'll be surprised how little you need a garbage collector. (My
personal choice is to clean up my own rubbish, but I'm not a zealot
about this).
We used GTK+ for our UI - it works on MacOS X (on X11) and on
Linux. We never
tried it on Windows.
I would not try to do a "one size fits all" UI - it will not work
well on any
platform. Decoupling the "engine" from the UI and allowing
differnt UIs would
be a better choice.
The current thought is to do a "reference" implementation for the
GUI clients using one language & widget set. Others can than port
this code to other languages or widget sets to give us more coverage
across the desired platforms. Whether we maintain these other ports
as part of the main body of Xastir-NG code or not will be up for
debate at the time. They may be considered entirely different
projects.
Sounds like a good plan, as it gives you a ready antidote to Second
System Disease. I'd avoid making the core too generic : it won't be
so bad that different clients have duplicated code in common if the
alternative is that every client needs thousands of lines of code to
convert from some abstract storage type into something useful.
--
Kristian
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