A work machine system includes a point cloud data sensor configured to detect point cloud data defining a plurality of points corresponding to a receiving vehicle and a grid map generator configured to identify a set of volumes and, for each respective volume in the set of volumes, identify a respective set of points having a location that corresponds to the respective volume and assign a point value to the respective volume based on the respective set of points. A parameter locator system is configured to identify a location of a structural object on the receiving vehicle based on the point values assigned to the volumes in the set of volumes and an unloading control system is configured to control the unloading operation based on the location of the structural object.