A method and system for searching for data covered by nodes in a quadtree are disclosed. Nodes at a selected level of the quadtree are encoded with an index. The index nodes store data related to the level of descendants and ancestors of each index node. To search for data covered by a particular desired node, the index node ancestor or descendant of the desired node is determined. Based on the data in the index node, the desired node can be located without a full traversal of the quadtree. The quadtree nodes store elevation data for points on the Earth.