[Xastir] ESRI shapefiles

[James Ewen]

> > One thing that I'd like to do for Xastir is pull the data 
> apart into 
> > various layers. Right now, I get every road in Alberta drawn when 
> > zoomed out. I'd like to pull only major highways into a 
> map, the next 
> > map would have secondary roads, and the close in layer 
> would have all the local roads.
> 
> If you could easily do that, you'd have the fastest map 
> system that you could do with Xastir currently.
> 
> You wouldn't have to read and skip those features that you 
> weren't intending to draw.

PalmAPRS maps have zoom level information encoded into them. There's no way
you can display fine details on a Palm when zoomed out a long way. 

There's no reason that this concept has to be limited to the Palm platform.
In my opinion, all vector maps should have this included in their
definition.

With the dbfawk file, I'd assume that all data still needs to be read, to
determine if it needs to be displayed or not. Does this speed up the display
time since it doesn't have to draw the lines? 

My road data for Alberta is 40 MB in size... It takes about 5 seconds to
draw the map for me. It would be nice to speed that up.

>From what I understand of the Xastir map implementation, what I'd need to do
is:

Make 1 map of Alberta with only the main highways..
Make a couple maps with secondary highways, splitting the province up into
say 4 sections.
Make many maps with street level detail, splitting the sub areas into a
large number of sections.

Each level of map would then have it's attributes set so that it display at
appropriate zoom levels. This would allow Xastir to only load the most
appropriate sections of data, by not only zoom level, but also area to be
displayed.

James
VE6SRV




> Perhaps Tom might have a clue as to whether this could be 
> done easily.  I haven't tried that.  You might be able to 
> easily create some tools using ogr2ogr or shapelib to do it.
> 
> -- 
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