osmandapp/Osmand — pull request #163 by jmakovicka (2012-02-16 20:33:02+00:00)
Title: Skip downloading empty tiles

Hi,

recently, I proposed an approach to reduce download bandwidth in tile
batch downloader by checking of the tile contents. The idea was to
check four quadrants of each downloaded tile, and skip all tiles on
higher zoom levels in the corresponding quadrants if the quadrant is
empty (contains only pixels of the same color).

This branch adds the above functionality. It makes a difference especially
for coastal areas like eg. Barcelona or the Netherlands.