Tile Visibility Index

In this paper, an encoding for image tile visibility index is proposed. Image tile visibility index is a structure to describe visibilities of image tiles. The index can be used to improve response time of a web map service using image tiles by reducing numbers of requests and responses of image tiles based on the visibility information. The image tile visibility index needs to be transferred from a web map server to a web browser, therefore an encoding of the image tile visibility index is required. In this paper, we provide a data model for the image tile visibility index and present an encoding for the index.