https://dl.acm.org/citation.cfm?id=3274985
https://pdfs.semanticscholar.org/3425/a9ba03ba65cc9e9e0a0c1b73a8359e6772ac.pdf
https://www.perrygeo.com/
http://brian-mcgill-4.ums.maine.edu/postgis_zonal.pdf
http://www-cs.ccny.cuny.edu/~jzhang/papers/zonalstat_tr.pdf
http://www.guru-gis.net/efficient-zonal-statistics-using-r-and-gdal/
https://robbymarrotte.weebly.com/blog/faster-zonal-statistics