[Xastir] APRSPoint discussion from APRS sig

[Tom Russo]

On Fri, Dec 03, 2004 at 03:28:04PM -0500, we recorded a bogon-computron collision of the <mckeehan at mckeehan.homeip.net> flavor, containing:
> On the APRS sig, there was some discussion about APRSPoint vs Xastir.
> 
> I thought I would toss my comments about using other mapping software into
> this group to get your feedback.
> 
> I use Delorme Street Atlas USA 2004 and Delorme Topo USA 3.0.
> 
> These have some features that I really like:
> 
> These are listed in the order that I find them useful.
> 
> 1. Fast map scrolling.
> The biggest improvement that I would like to see in Xastir is faster map
> scrolling/changing. I suspect that the reason it is currently as slow as it is
> is because of the large number of map formats supported (one of Xastir's
> greatest features). One way that I can imagine increasing the speed would be
> to convert all maps to a single format. Is this on one of the developer's idea
> list? Maybe not all map types would be able to fit into this format, but it's
> a thought worth exploring.

I think that the main reason for this speed issue is that Xastir reads in
all the maps every time it zooms or pans.

If it kept an in-core cache of some form or other of the maps in the current
view, then it could be sped up quite a bit, but there's a cost to that, too.  
Management of the cache could be tricky, and with a lot of maps some tradeoff 
would have to happen to keep memory bloat down.  

The new map caching of online tiger maps is a step in this direction --- if
a map has already been downloaded recently it isn't downloaded again and the
cached version is used, but the cache is still disk based.

> 2. "smart" zooming (i.e., different level of details shown at different zoom
> levels)
> I just began playing with Xastir's Auto Maps feature this past week; this
> comes very close to giving me what I want in the smart zooming...it just takes
> some knowledge, thought and patience :-)

Automaps is sort of the old way to do map management.  Use of the map chooser
to prune which maps get read in at specific zoom levels is better than the
automaps feature.  And for shapefile maps there is a way (through dbfawk) to
prune different line types depending on zoom level.  The problem is that
this is done every time a map is read in, and that is done every time the
view changes.

> 5. Fast flexible find feature.
> I have not played with this feature in Xastir very much, but when I have, it
> seems to be much less flexable than Delorme's; and Delorme has many more
> points of interest to display (businesses, etc).

They probably have access to a large commercial database of such points of
interest.

One can build "GNIS" format databases of points of interest, and use the 
Locate Map Feature feature of xastir to do some of this.  But getting the 
database is the trick.

> 6. Ability to "draw" on maps.
> I do this now in Xastir by creating my own shapfile maps and selecting them to
> display. Delorme only tops it by allowing you do do it interactively.

I'm on the hook to work on this, but wound up being much busier than I thought
and haven't had time to do anything at all except begin and discard two 
different toy graphical object management libraries.   Someday I'll get on it.

> If I could get something like APRSpoint to work with current versions of
> Street Atlas, I would probably use that in place of Xastir (on my Windows
> box). What do you guys think? Is this comparing apples to oranges or do some
> of my ideas have merit?

AFAIK there is no plan to make Xastir work with any non-open-source mapping
product.  There might be a way (and there's been some discussion of it) to 
make some sort of generic interface to Xastir from which data can be extracted 
and displayed in some other package, but nobody is working on that yet.

-- 
Tom Russo    KM5VY     SAR502  DM64ux         http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://www.qsl.net/~km5vy/
 "That which does not kill me is better than that which does."
    --Irving Nietzche, lesser known of the famous Nietzche twins