[OSM-dev] SVG maps and web browsers (was: Re: "Retina" tiles - best way to support them?)

[Igor Brejc]

SVG has several problems:

   1. It's a general-purpose graphics format. It allows a lot of things,
   but that comes with a cost - implementing and maintaining a SVG rendering
   engine is difficult, making it efficient is even more so.
   2. Although SVG is supposed to be a standard, not everyone implements
   its renderers (or converters) the same way. Adobe's implementation is
   particularly buggy & non-compliant (see
   http://igorbrejc.net/openstreetmap/maperitive-vs-adobe-illustrator). Oh
   yes, and _very_ slow, especially if you want to have high-precision text
   positioning on a per-letter basis (see
   http://maperitive.net/docs/manual/Commands/ExportSvg.html#Precision%20Typography)
   - this is why Maperitive SVG sample you tried is so slow.
   3. You're stuck with existing implementations of rendering engines.
   Writing your own would be a mammoth (and wasteful) effort, because of the
   point #1.

SVG comes in handy when you want to have a map that can be imported as a
vector drawing into desktop publishing software (Illustrator, Inkscape
etc). For rendering maps on the fly on mobile devices, I'd recommend using
a native renderer or HTML5.

Igor

On Sun, Jul 1, 2012 at 11:16 PM, Robert Joop <
5313501608656osm at rainbow.in-berlin.de> wrote:

> On 12-06-28 19:09:42 CEST, Stefan de Konink wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA512
> >
> > On 27-06-12 23:12, Robert Joop wrote:
> > > Why unreadable? What viewport setting do you use?
> >
> > A mapquest widget is used within a native app.
>
> Ok, I had web browsers in mind, out of personal experience.
>
> > > How good is the SVG support on mobile devices?
> >
> > <http://en.wikipedia.org/wiki/Scalable_Vector_Graphics#Mobile_profiles>
>
> Well, this doesn’t tell me anything about the quantity and quality of
> the support on the devices out in the field.
> But this doesn’t concern you, I suppose, as with an app you’ll cover
> only a small part of the market (expressed in percentage of devices,
> not in percentage of market share, of course), and you can know those
> devices fairly well, or bring along the libraries as needed...?
>
> Me, thinking along mobile web browser support, am much more reluctant
> when it comes to using SVG heavily on them.
>
> Actually, thinking about it, I wonder whether desktop browsers are up for
> it. Following the hint on http://wiki.openstreetmap.org/wiki/SVG
> I tried the OSM SVG export, central Cologne at zoom level 15, and loaded
> the result in Firefox 3.6 on my netbook: it takes ages to render, some
> 45 seconds.
> The Maperitive example offered there for the center of Dublin takes some
> 30 seconds to render.
>
> The remainder of the tests is with the OSM Cologne export.
> My desktop PC is even slower, 100 seconds with Firefox 3.6.
> A more current desktop PC at work:
> - 31 seconds with Firefox 3.6
> - 6 seconds with Firefox 10
> - 2 seconds with Chrome 20
>
> But how about mobile devices? In case anybody's as curious as myself:
>
> Acer A100 (Android 4): some 14 s
>   Opera Mobile on it seems slightly faster
> Samsung Galaxy Tab 10.1: also some 14 s; panning and zooming almost fast
>   enough to use.
> Windows Phone 7: no SVG support
> HTC Desire, HTC Sensation: I get a blank page!
> Apple iPhone: more than 2 minutes till it has finished rendering, and
>   then panning and zooming feels glacial as well.
> Apple iPhone 4: some 33 s where nothing seems to happen, then the finished
>   result appears. Panning and zooming is too slow to use.
>
> (On most devices, one can watch the map getting rendered.)
>
> To sum it up, I believe it is safe to say that heavy use of SVG like those
> from OSM exports should only be used on targets you know very well. ;-)
>
> YMMV,
> have fun,
> rj
>
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