I've got data from all over Europe in one feature class projected in Web Mercator Auxiliary Sphere. Due to the fact, that length and area values are not usable I'm now working on a python script (ArcGIS 10.0) that projects the features to the corresponding UTM zones and writes the calculated values back to the orginal fc.
First the script assigns the corresponding UTM zone to each feature via spatial join with an UTM zone fc. Within the next step I'd like to select all features within one UTM zone and project them (e.g. all features with value 32 will be projected to UTM ETRS89 zone 32 and so on). My problem is, that project_management does not have a "where_clause" so what will be the best way to make this selection? I've got lot's of data in one feature class and many feature classes, so speed does matter...
If anybody knows a better way to get precise length and area values for data in Web Mercator projection, please let me know!
Thanks in advance!