def validate(self, field_data, all_data):
        pass
Converts EPSG:900913 to pyramid pixel coordinates in given zoom level
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-0.96/django/db/models/fields/__init__.py/Field.validate--crossover with--dataset/ETHPy150Open Ecotrust/create-utfgrids/globalmaptiles.py/GlobalMercator.MetersToPixels