I want to statistically sample a map printed on graph paper by using Google Earth to print out an aerial view of on island to compute the area of the island that is inhabitable by animals. I'm thinking of counting the total number of axis points of the graph paper and subtracting out those axis points that are uninhabitable due to their being covered by road or buildings. I would count each uninhabitable axis point as being the area of one whole cell of the graph paper and thus estimate the habitat area by this sampling process.
Is this a sound approach? Is there a better way to do this?