[OSM-talk] SVG tiles

[elvin ibbotson]

Yup! Osmarender seems to produce SVG, and I guess SVG is an  
intermediate stage in producing the bitmap T at H tiles, but
what I am suggesting should be considered is a server that would  
deliver tiles in SVG format instead of/as an alternative to bitmap  
tiles. Could this be done simply (as if anything was ever simple :-)  
caching the SVG between running Osmarender and converting SVG to  
bitmaps?

On 21 Apr 2008, at 18:00, 80n wrote:

>
> On Mon, Apr 21, 2008 at 2:33 PM, elvin ibbotson  
> <elvin.ibbotson at poco.org.uk> wrote:
> poco.org.uk
>
> I have developed a mobile-phone Java app (called 'mom') to navigate  
> OSM maps and save GPX tracks (amongst other things) which will soon  
> be out there for people to download. It uses mapnick PNG tiles at 5  
> of OSM's scales (3, 6, 9, 12 & 15) which look nice but are quite  
> big files to download to a phone (typically 12kB-15kB for scale 15)  
> so take a significant amount of time and eat into a user's data  
> allowance to fetch.
>
> I considered using the compact binary downloads aimed at mobile  
> apps, but this is raw data and the graphics limitations of mobile  
> Java mean the maps drawn from it would not look very pretty.
>
> I am fairly ignorant of OSM data structures and back-room software  
> but I understand SVG is used in producing bitmap tiles. As I  
> understand it, the idea of SVG is not only to give nice, scalable,  
> graphics, but to do so using smaller file/download sizes than  
> bitmaps. Many/most of the newest mobile phones are able to draw SVG  
> graphics in Java, as are browsers, and desktop Java will soon  
> include SVG graphics, so it looks to me like the way forward. If  
> tiles were available as SVG I am sure it would be relatively easy  
> to substitute them for bitmap tiles in slippy maps or apps like  
> mine. Not only would downloads be faster but a smaller range of  
> scales would be needed, with the same data set and appearance being  
> used for a range of scales and scaling of the SVG image used for  
> intermediate (or infinitely adjustable) scales.
>
> I had been intending to get round to mailing this list enquiring if  
> SVG downloads were possible/available when the Export tab appeared.  
> My initial delight** was slightly diminished when I exported a map  
> in two formats - SVG and PNG - and found the SVG version was 340kB  
> while the PNG file was 132kB. A glance at the SVG data suggests  
> that text is actually drawn (sometimes more than once (for  
> background then again for the text itself) using long, elaborate  
> paths and shape definitions of every character at every orientation  
> and size, rather than just using the SVG text element!!! I suspect  
> it also incorporates bitmap images as icons rather than using SVG  
> definitions. I think SVG is the way forward, but not if the file  
> sizes end up almost three times bigger than bitmaps!
>
> Take a look at Osmarender.  This creates proper SVG.  Details here:  
> http://wiki.openstreetmap.org/index.php/Osmarender
>
>
>
> I suggest that, if has not already been done and is hidden  
> somewhere I haven't looked, that a server should be dedicated to  
> scalable map tiles using a compact and efficient implementation of  
> SVG coding.
>
> **Hats off to those involved, by the way <     :-)
>
> elvin.ibbotson at poco.org.uk
>
>
>
>
>
>
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