Raster Map Tile Diff Transmission for Bandwidth Reduction
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Solution Overview
Problem
Existing digital map transmission methods consume significant bandwidth and are inefficient when updating raster map images on client devices, as they require sending entire new images instead of only the differences.
Innovation Solution
A method where a network server generates and transmits a description of the pixel differences between the existing and new raster map images, allowing client devices to overlay and update the images efficiently, reducing bandwidth usage by using highly compressible difference raster map images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the server sends a new raster map image to replace the old version, then the map data is updated on client devices, but the bandwidth consumption increases significantly
Solution Approach 1:
The patent extracts only the changed portions (diff images) from the complete raster map image and transmits only these extracted differences to client devices. This allows map updates without transmitting the entire image, significantly reducing bandwidth consumption while maintaining update reliability.
Solution Approach 2:
The patent segments the raster map image into multiple tiles and further divides changed areas into separate diff image segments. Each segment represents a specific geographic region or change type, allowing selective transmission of only necessary portions rather than the complete image.
2Reliability
If the server transmits complete raster map images, then the map data is accurately updated, but the transmission time increases
Solution Approach 1:
The patent extracts only the essential change information (diff images) needed for map updates and transmits only these extracted portions. This extraction approach maintains update accuracy by capturing all necessary changes while dramatically reducing transmission time compared to sending complete images.
Solution Approach 2:
The patent transmits only the partial information needed for updates (the differences) rather than the complete image data. This partial action approach provides sufficient information for accurate map updates without the excessive transmission time required for full image transmission.
3Adaptability or versatility
If vector map data is used requiring client-side rendering, then the map can be scaled, but the computational cost on client devices increases
Solution Approach 1:
The patent uses raster image copies (diff images) instead of vector data, allowing client devices to simply overlay and composite images rather than performing computationally intensive vector rendering. This copying approach reduces client computational cost while maintaining adaptability through pre-rendered raster formats.
Solution Approach 2:
The patent substitutes the mechanical computation process (client-side vector rendering) with a simpler image processing operation (raster overlay and compositing). This replacement reduces the computational burden on client devices while preserving map scalability and visual quality.
Data Source
AI summary
A network server receives, from a client device, an indication of a first raster map image that depicts a geographic map of a certain region and a certain zoom level. The network server obtains a second raster map image corresponding to the geographic region and the zoom level and generating a description of a difference in pixels between the indicated first raster map image and the second raster map image. The network server then provides the description of the determined difference in pixels to the client device for generating the second raster map image at the client device.