[OSM-talk] Newbie - queries and usability suggestions

[Robert (Jamie) Munro]

Lars Aronsson wrote:
> Calum Polwart wrote:
>> I've uploaded a track, and started doing some mapping from it.  
>> That's fine.  But because my track in above 54' N it doesn't 
>> render on slippy.
> 
> The new slippy map is useless.  The old slippy map was useless 
> too, but in different ways.  Every approach I have seen has been 
> useless in its unique way.

The new slippy map is most certainly not useless. It's just still a
beta. It's a lot more useful that the previous map was getting (in the
areas it covers), and is getting better. I expect making it more up to
date and covering the whole world is a much simpler problem than getting
it to the stage it is at now.

> Ultimately, we need some solid GIS experience on how to make the 
> database, API and slippy map generation fast and scalable.  A new 
> tile must be generated in a tiny fraction of a second (20 ms or 
> so), independent of the scale, and it must be possible to 
> invalidate only the right parts of the tile cache.

I disagree. If an edit can appear on slippy within an hour, that is
easily fast enough (as long as people are made aware that they should
expect up to an hours delay). I don't know what the rate of tile
invalidation will be

>  In a map of 
> England, the tile that covers London is the real challenge.  It is 
> based on many thousands of line segments, and doesn't really need 
> to be redrawn if only a small street is modified. 

Really it should only include roads that are major enough to show up -
an algorithm based on road length might be a good method to pick
important roads. Tile invalidation would only happen at low zoom levels
if a long road was edited, and possibly only if it was edited 'enough'.

Robert (Jamie) Munro

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