# Difference in vector / raster area measurements

I'm comparing raster and vector distance zones.

So I created a line, calculated the Euclidean distance, and reclassified the raster to two zones: from 0-10m and 10-20m. To compare it with vector distance, I created a Multiple Ring Buffer with the same line and the same two zones, 0-10m and 10-20m.

When I'm calculating the area, for example for the 0-10m zone, the (vector) buffer has an area of 1475 m² while the Euclidean distance raster for the same zone has an area of 1493 m²!

Can someone please explain why those two values differ?

• If you were to select all distances in the raster that are less than or equal to the buffer radius and inspect the boundary of that zone, you would find that it consists of whole cells in the raster, and thereby only discretely approximates the vector buffer. You really should be comparing the raster solution to a rasterized version of the vector solution: any substantial discrepancy between those two would be worth investigating. – whuber Jun 23 '14 at 20:16