Abstract: In a system of a client and a server, the server stores three dimensional CAD data in a cache. The CAD data is stored in the cache in levels of detail further divided into tiles. When a client receives a request from a user to view part of a CAD file, the client determines which portion of the CAD file is being viewed, and at what resolution. The client then checks a client cache for tiles already stored for the desired view. The client requests the view data from the server by providing to the server the client's resolution, the boundary of the viewing area and a list of tiles that the client already has. The server uses the request information to return to the client only the data that is needed for the client's resolution and that is not already stored on the client.