DevelopmentSeed
Land forms as a black and white mask
The land forms were designed as a black-and-white mask. The advantage of doing this versus using Mapnik's transparency capabilities is that it gives you the ability to make transparency out of non-background objects and avoids any weirdness associated with overlapping semi-opaque shapes.
Blog post with more details at developmentseed.org/blog/2010/dec/21/designing-single-cus....
Land forms as a black and white mask
The land forms were designed as a black-and-white mask. The advantage of doing this versus using Mapnik's transparency capabilities is that it gives you the ability to make transparency out of non-background objects and avoids any weirdness associated with overlapping semi-opaque shapes.
Blog post with more details at developmentseed.org/blog/2010/dec/21/designing-single-cus....