Efficient pre-computing of simplified vector data for rendering at multiple zoom levels

Abstract

Aspects of the invention relate generally to accessing, storing, and processing vector data to represent various geographical features such as roads, rivers, lakes, countries, continents, and oceans on one or more maps. More specifically, the vector data may be pre-simplified for rendering at different zoom levels. The simplification process is based on removing vertices from vector data in order to reduce the number of points in a given polygon or line. As this process is very expensive in terms of time and processing power, the system and method allow for estimation of the proportion of vertices which that would be removed from the original geometry. Based on this estimation, one may decide whether or not the simplification is worth the effort to compute and store the simplified data.

Description

BACKGROUND OF THE INVENTION[0001]Various map services employ vector data to represent geographical features such as roads, rivers, lakes, countries, continents, oceans, etc. For example, a geographical feature or object may be represented by connecting the vertices of one or more vectors. While the great majority of these features are relatively small, for example, about 1-1.5 kilobyte, a significant number of them may be extremely large, for example, on the order of a megabyte or larger. The largest features may involve hundreds of thousands, or sometimes millions of vertices. Transmitting all of this information to a client device to render these features at all zoom levels based on their original geometry is impractical and wasteful of computing resources.[0002]These map services may receive a request from a client device for a map of a given location and, in response, transmit a portion of the map information for display on the client device. These services may also transmit hig...

AI Technical Summary

Benefits of technology

[0006]The simplification process is based on removing vertices from vector data in order to reduce the number of points in a given polygon or line. Such a process may be very expensive in terms of time and processing power; thus, aspects of the invention allow for estimation of the proportion of vertices that may be removed from the original geometry. Based on this estimation, one may decide whether or not the simplification is worth the effort to compute and store the simplified data.

Problems solved by technology

Transmitting all of this information to a client device to render these features at all zoom levels based on their original geometry is impractical and wasteful of computing resources.

However, at the lowest zoom level many objects may no longer be visible as they may overlap one another or be drawn within a single pixel.

However, when zooming out at world level, all of the finer details in the geometry of the Atlantic Ocean (or the Massachusetts coastline) are no longer distinguishable.

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