Geometry Boost List: [ggl] spatial indexes - design

Subject: [ggl] spatial indexes - design
From: Barend Gehrels (barend.gehrels)
Date: 2011-01-12 17:13:57

hi Adam, List,

Sorry to start a new thread about this (working from another computer 
now). I asked today how the interface would look like and after that 
remembered that it was once long ago discussed in a private e-mail. 
Anyway, now that Boost.Range adaptors are within Boost, I think that 
range adaptors might be the perfect interface for usages of spatial indices.

See the page http://bit.ly/f1Zmu2

With, for example: boost::count( rng | boost::adaptors::filtered(pred), 
out );

So our spatial index might be queried using:

// "my_polygon_type", a polygon type somewhere
// "polygon_collection", a collection of polygons defined somewhere
// "my_box_type", a box type somewhere
// "my_spatial_indexe", a spatial index defined somewhere, and filled 
with the polygon collection

BOOST_FOREACH(my_polygon_type const& p, polygon_collection | 
boost::geometry::adaptors::spatial_filter(my_box_type(my_spatial_index, 
5, 5, 10, 10)))
{
   // do something with this polygon p, guaranteed intersecting the 
specified box
}

That (or slightly adapted) will probably only work if "my_polygon_type" 
has some identifier stored in the spatial index, together with the 
bounding box of that polygon. This identifier might be defined by a 
traits class defining how the identier (e.g. an integer) is accessed 
from the polygon. In some cases (point set) the identifier might be the 
point itself (so then the spatial index stores points).

So this is how it might be from user perspective. Seems workable? I 
realize I omitted the filling but that is probably more straightforward.

Regards, Barend