Abstract: Aspects of the disclosure relate to generating a digital terrain model (“DTM”) from a digital surface model (“DSM”). For example, the DSM may include a plurality pixels associated with coordinate information and elevation information, including the elevation of features such as buildings and large vegetation. Initially, a set of vertices defining a polygon may be identified. A set of seed pixels, corresponding to points of the DSM of “bare” earth (without buildings or large vegetation) may also be identified. These may be the same or different from the set of vertices. An adaptive flood filler algorithm is used to evaluate the pixels of the polygon starting with the seed pixels. This process validates or invalidates the state of the pixels. The result is an approximation of a DTM for the polygon.

Abstract: Aspects of the disclosure relate to generating a digital terrain model (“DTM”) from a digital surface model (“DSM”). For example, the DSM may include a plurality pixels associated with coordinate information and elevation information, including the elevation of features such as buildings and large vegetation. Initially, a set of vertices defining a polygon may be identified. A set of seed pixels, corresponding to points of the DSM of “bare” earth (without buildings or large vegetation) may also be identified. These may be the same or different from the set of vertices. An adaptive flood filler algorithm is used to evaluate the pixels of the polygon starting with the seed pixels. This process validates or invalidates the state of the pixels. The result is an approximation of a DTM for the polygon.

Abstract: Methods for drawing an aligned rectangle or rotated rectangle on an electronic device are provided. In one aspect, a method includes receiving a first user input at a first location of a movable indicator in a graphical user interface includes an x-y axes, and determining whether the movable indicator has moved from the first location prior to receiving a second user input. The method also includes providing, for display, a rectangle based on coordinates of the first location and the second location and aligned to the x-y axes. The method further includes providing, for display, a first rotated rectangle, based on coordinates of the first location and a third location of the indicator, which is rotated about the x-y axes based on an angle calculated from the first location and the second location. Systems, graphical user interfaces, and machine-readable media are also provided.