1. A computing system comprising: a processor; and memory that comprises instructions that, when executed by the processor, cause the processor to perform acts comprising: comparing a first property of a first superpixel assigned to a first pixel in a first radar image and a second property of a second superpixel assigned to the first pixel in the first radar image, wherein the first pixel is included in a first edge of the first superpixel; and in response to determining the first property and the second property are similar, identifying the first superpixel and the second superpixel as having similar radar-reflecting properties and labeling the first edge as an internal edge; or in response to determining the first property and the second property are dissimilar, identifying the first superpixel and the second superpixel as having contrasting radar-reflecting properties and labeling the first edge as an external edge.