A method for dynamically generating and rendering an object bounding fence in a mixed-reality scene, the method comprising: accessing a spatial mapping of an environment, the spatial mapping including perimeter edge data describing one or more perimeter edge(s) of an object (1205, 1210, 1215, 1220, 1225) located within the environment; wherein the perimeter edge data describes a portion, but not all, of the one or more perimeter edge(s) of the object such that the perimeter edge data constitutes incomplete data, and wherein the spatial mapping is a sparse spatial mapping as a result of including the incomplete data for the object; generating a gravity vector of a head-mounted device that is operating in the environment and that is displaying a mixed-reality scene; based on the perimeter edge data and the gravity vector, determining two-dimensional boundaries of the object within the environment; generating a bounding fence mesh (1335, 1340, 1345, 1350, 1355) of the environment, the bounding fence mesh identifying the 2D boundaries of the object within the environment; and rendering, within the mixed-reality scene, a virtual object (1410, 1530, 1535, 1540, 1545) that is representative of at least a portion of the bounding fence mesh and that visually illustrates a bounding fence around the object; wherein a visualization of a 2D bird's eye view of the environment is generated using the spatial mapping of the environment and is displayed within the mixed reality scene; wherein when the HMD determines that the HMD is located within a predetermined or pre-established threshold distance to the object, then the HMD triggers the display of the bird's eye view. accessing a spatial mapping of an environment, the spatial mapping including perimeter edge data describing one or more perimeter edge(s) of an object (1205, 1210, 1215, 1220, 1225) located within the environment; wherein the perimeter edge data describes a portion, but not all, of the one or more perimeter edge(s) of the object such that the perimeter edge data constitutes incomplete data, and wherein the spatial mapping is a sparse spatial mapping as a result of including the incomplete data for the object; generating a gravity vector of a head-mounted device that is operating in the environment and that is displaying a mixed-reality scene; based on the perimeter edge data and the gravity vector, determining two-dimensional boundaries of the object within the environment; generating a bounding fence mesh (1335, 1340, 1345, 1350, 1355) of the environment, the bounding fence mesh identifying the 2D boundaries of the object within the environment; and rendering, within the mixed-reality scene, a virtual object (1410, 1530, 1535, 1540, 1545) that is representative of at least a portion of the bounding fence mesh and that visually illustrates a bounding fence around the object; wherein a visualization of a 2D bird's eye view of the environment is generated using the spatial mapping of the environment and is displayed within the mixed reality scene; wherein when the HMD determines that the HMD is located within a predetermined or pre-established threshold distance to the object, then the HMD triggers the display of the bird's eye view.