[gdal-dev] Why are fields required in osmconf.ini file?
issworld2000 at yahoo.com
Sun Dec 4 16:53:22 PST 2016
Thank you for the information once again Jukka!
On Sunday, December 4, 2016 6:03 PM, jratike80 <jukka.rahkonen at maanmittauslaitos.fi> wrote:
Brad Hards wrote
>> Why is that so? Why do field names need to be predefined before their
>> extraction from the .osm file?
>> Why can't only those fields which already exist in the .osm file, be
> How could ogr2ogr possibly know what fields are in the file? It would
> a full parse of the file, and likely give you many more fields than you
> possibly want in any case.
Especially with shapefiles it is also practically impossible with any bigger
datasets. Dbf file can have only 255 fields, or 254 if fields may contain
NULL values https://msdn.microsoft.com/en-us/library/3kfd3hw9(v=vs.80).aspx.
There are 1012 different tags in the Irish OSM data today
http://taginfo.openstreetmap.ie/tags. It means that there are 758 more tags
than it is possible to save as fields into shapefiles.
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