[Tile-serving] [osm2pgsql] Coordinate precision not sufficient at very high zoom levels? (#519)

[damiendevienne]

Hello, 
I posted this question on the mapnik gitgub, but it seems not to be the right place 
I have some trouble with the shapes of my polygons using mapnik when these polygons are representing very very small area (at zoom 29 for example) The shape of the obtained polygon (see below) makes me think that the lat/lon coordinates are somehow cut or rounded 
Is there a way to increase precision of lat and long at osm2pgsql import ? Or is it something related to PostGis? Or to Mapnik? 

Any suggestions would be very welcome, 

Thanks

![image](https://cloudgithubusercontentcom/assets/15011328/11899895/8ed45ba8-a5a2-11e5-9bc8-186680eb49c4png)

NB: I checked that the precision of my input (xml osm) data was ok (in the file I load with osm2pgsql)

Here are the coordinates of the polygon on the right in the figure:
```console
lat                                         lon
368593577908583469593 -1364353178351570328175
368593577762137325493 -1364353178072946803923
368593577646674175341 -1364353177780122727825
368593577563547691867 -1364353177476531620016
368593577513732517659 -1364353177165732589060
368593577497812585619 -1364353176851369475742
368593577515974635261 -1364353176537128042867
368593577568005725809 -1364353176226692276884
368593577653295811913 -1364353175923701755323
368593577770844937902 -1364353175631709014226
368593577919274961729 -1364353175354137093223
368593578096845675418 -1364353175094240633314
368593578301475188752 -1364353174855066264115
368593578530764487411 -1364353174639418320169
368593578782025321772 -1364353174449825090164
368593579052311914879 -1364353174288509329415
368593579338455334948 -1364353174157362325047
368593579637100843271 -1364353174057921691542
368593579944747151700 -1364353173991353251893
368593580257787323262 -1364353173958437537294
368593580572551227093 -1364353173959560194817
368593580885348615084 -1364353173994708257055
368593581192512198541 -1364353174063469786859
368593581490440769244 -1364353174165038318222
368593581775641343512 -1364353174298223159155
368593582044770284867 -1364353174461462891998
368593582294672206245 -1364353174652843669890
368593582522417317904 -1364353174870121776507
368593582725335489059 -1364353175110749738508
368593582901047689404 -1364353175371906523594
368593582901047689404 -1364353175371906523594
368593582926684426582 -1364353175448112409640
368593582922754592346 -1364353175540891882633
368593582889304238748 -1364353175649157101645
368593582826725496560 -1364353175771638682079
368593582735752089974 -1364353175906900794701
368593582617450588046 -1364353176053357330488
368593582473207970196 -1364353176209291440557
368593582304715328135 -1364353176372875076083
368593582113948103895 -1364353176542189949316
368593581903142863965 -1364353176715251336759
368593581674771098022 -1364353176890030105994
368593581431510308732 -1364353177064477229408
368593581176212392592 -1364353177236547409734
368593580911870599692 -1364353177404223416147
368593580641584050994 -1364353177565539176896
368593580368521589463 -1364353177718603404855
368593580095884654213 -1364353177861621801981
368593579826869621741 -1364353177992917487416
368593579564630502432 -1364353178110951070323
368593579312241770296 -1364353178214338768726
368593579072662480556 -1364353178301868574351
368593578848701497463 -1364353178372514108219
368593578642984498472 -1364353178425447055133
368593578457923332081 -1364353178460047111287
368593578295687729351 -1364353178475908379141
368593578158179724369 -1364353178472845051772
368593578047011449783 -1364353178450893011586
368593577963486307425 -1364353178410309475055
368593577908583469593 -1364353178351570328175
```

---
Reply to this email directly or view it on GitHub:
https://github.com/openstreetmap/osm2pgsql/issues/519
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