[OSM-talk] OSMXAPI question: is it me, or...

[80n]

On Thu, Sep 11, 2008 at 8:27 AM, Lambertus <osm at na1400.info> wrote:
> Thanks for the quick action. The amount of data downloaded by the query was
> significantly more then before so that was already promising. Looking at the
> data in JOSM showed no sign of crippled roads so that bug appears to be
> squashed.
>
> However the bbox parameter still does not seem to do what I expect from it
> (data returning from UK, NL, DE and BE instead of roughly a province in NL).

Given that relations can contain an arbitrary collection of
unconnected ways the notion of where a relation is might be a bit
tricky.

The current algorithm draws a box around the extent of each relation
and then tests whether that overlaps with the bbox you have requested.

Having thought about it for a moment it should probably test the
extent of each way within the relation.  This would give better
precision.

I'm not sure if this is the cause of what you are seeing, but it seems likely.


> Reversing the parameters gives almost but not exactly the same result:
>
> -rw-rw-r-- 1 lambertus lambertus 16519465 Sep 11 08:45 data.osm.4 (wget
> http://www.informationfreeway.org/api/0.5/relation[network=rcn][bbox=5.5,52.0,6.3,52.3])
> -rw-rw-r-- 1 lambertus lambertus 16397318 Sep 11 09:14 data.osm.5 (wget
> http://www.informationfreeway.org/api/0.5/relation[bbox=5.5,52.0,6.3,52.3][network=rcn])

The order of the predicates should not make any difference at all.
All I can think is that the database had changed during that time, so
you would have got the same results either way.

>
> The one that was downloaded half an hour later is a bit smaller to my
> surprise. I tried to find out what was the difference but visually there are
> no changes to spot, but diff outputs so much that I don't know what to do
> with it.
>
> 80n wrote:
>>
>> I've found a bug and fixed it.  Can you try again and let me know how it
>> goes?
>>
>> 80n
>>
>>
>