[Xastir-dev] Optimizing Shapefile drawing

[Tom Russo]

On Thu, Dec 16, 2004 at 11:14:50AM -0800, we recorded a bogon-computron collision of the <archer at eskimo.com> flavor, containing:
> On Thu, 16 Dec 2004, Tom Russo wrote:
> 
> > I had an idea today for how to improve the speed of shapefile rendering.
> > I wanna run it up the flagpole first.
> >
[...]
> 
> It sounds like a great idea!  The only thing that would make me
> hesitate would be if we were ready at this point to go to an SQL
> back-end.  That's a ways off, so these improvements should be
> useful for quite a while.

Nod.  The SQL back-end is one that could be much better than anything.  GRASS
has gone to treating every type of vector layer in a way that can be 
queried with SQL (with some unfortunate side-effects, but overall it's
extraordinarily powerful).  I was just thinking how much better an
SQL query engine would be for customizable rendering of vector layers 
than dbfawk ever will be.

> How hard would it be to generalize it to cover ALL types of vector
> maps?  In that case we could speed up anything OGR could handle plus
> Shapefiles, PocketAPRS, dosAPRS, WinAPRS maps.

The technique would be applicable to any layer for which sub-rectangles
can be extracted.  For shapefiles that's trivial, because each point, polyline,
and polygon has its bounding box stored with the file.  For others it might
require that we compute one while generating the rtree.

-- 
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