1. A method comprising: determining pixels, in a portion of a depth map of an environment, that comprise edge pixels, wherein an edge pixel represents an edge of an object in the environment; and determining edges of an object in the environment by connecting the edge pixels; wherein the determining the pixels that comprise edge pixels comprises, for each pixel in the portion of the depth map: accessing a depth map that indicates, for each pixel of a group of pixels, a depth measurement of each respective pixel from a camera that obtained the depth map, the group of pixels comprising the pixel and pixels that are immediately adjacent to the pixel in the portion of the depth map; estimating a plane for the pixel based on a depth measurement of the pixel and respective depth measurements for the pixels that are immediately adjacent to the pixel in the depth map, the estimating the plane based at least in part on a total least squares algorithm or an approximation of a total least squares algorithm; determining inlier pixels, the inlier pixels comprising pixels of the group of pixels that belong to the plane; determining outlier pixels, the outlier pixels comprising pixels of the group of pixels that do not belong to the plane; determining a ratio of the inlier pixels to the outlier pixels; determining that the ratio is less than a threshold ratio; and determining that the pixel is an edge pixel at least partly in response to determining that the ratio is less than the threshold ratio, an edge pixel representing at least a portion of an edge of the object.