Throughout the course of the year the Village of Oak Brook, IL receives questions from residents concerning private tree ownership, typically to determine responsibility for maintenance. Often times these questions can be resolved by a trip to the field by village staff, by referencing building surveys which include tree planting plans, or by utilizing aerial imagery with property lines to see which property the stem of the tree is located on. If these options don’t yield an acceptable answer to the question, a surveyor needs to be called in to mark property boundaries to determine which property a tree is located. In an effort to avoid calling in a surveyor for a dead tree removal dispute involving four village properties, village engineers requested that Geographic Information System (GIS) staff use available Light Detection and Ranging (LiDAR) data to determine the location of a tree centroid to help pinpoint exactly who owns the tree.
GIS staff first determined the general location of the tree, under the direction of the village engineer, using aerial imagery. After the location within the village was determined, LiDAR bare earth elevation points for that area, which represent solid ground around vegetation, buildings, water, etc, were loaded into the GIS software. Once the bare earth points were loaded for the area in dispute a location in middle of the bare earth point cluster with no data was discovered, representing the canopy of the tree in dispute. As shown in the associated image, a centroid was then placed in the middle of the approximate tree canopy indicated by the LiDAR point cloud, representing the trunk location, which allowed village engineers to see which property the trunk of tree landed on. Without GIS, the resolution to this issue would have involved contacting a surveyor to come out, measure each property, and determine ownership. This process would have taken longer and cost significantly more than the process that was used, which involved leveraging the existing GIS information.