[Xastir] [tiling] reading tiles slow

[Tom Hayward]

On Tue, Aug 17, 2010 at 09:29, Jerry Dunmire <jerry at dunmire.org> wrote:
> Of course there would still be a problem when combining bitmaps from
> different projections, UTM is far different than Mercator and that is
> only two of several possible projections. One of the combined maps
> would be slow to load. On the other hand, combining bitmaps might not
> be a common and useful enough feature and perhaps it should be dropped
> in order to speed up the load times.

My use case: At a public service event, displaying one JPEG .geo map
(sourced from a scanned handout from race officials, unknown
projection) over a sea of OSM maps.

I usually only use one base raster layer, like OSM, but may overlay
single maps for special purposes. In this use case, I think it would
be much faster to optimize projection for OSM maps, because there are
a lot more OSM tiles than special-case overlay(s). Not knowing the
projection of my scanned map, I wouldn't be bothered if it were
displayed in OSM projection without conversion. And the way I use it,
I'm usually zoomed in enough that the projection differences would be
minimal anyway.

It would be nice if projection was a configuration option, although I
would guess a lot of code modification would be required to slip this
in, and could be prone to bugs if something was missed.

Tom KD7LXL