Map Server Tile Rendering Bandwidth Optimization

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Solution Overview

Problem

The transmission of high-resolution map images for interactive digital maps is inefficient due to high bandwidth requirements, with existing compression methods either causing noticeable quality loss or not providing significant bandwidth savings, especially with the proliferation of high-resolution screens in devices.

Innovation Solution

A map server generates multiple image layers with varying resolutions for different types of geographic data, applying appropriate compression techniques such as lossy or lossless compression based on the data type, allowing for efficient transmission and client-side rendering of digital maps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high-resolution map images are transmitted to support high-resolution screens, then image quality is improved, but bandwidth usage increases significantly

Engineering Contradiction:
Improveimage qualityVSAvoidbandwidth usage
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The map image is divided into multiple layers, each representing different geographic features (roads, water bodies, buildings, labels) at different resolutions. This segmentation allows selective transmission of layers based on their importance and resolution requirements, reducing overall bandwidth usage while maintaining image quality for critical features.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different layers are assigned different resolutions based on their specific requirements. Critical features like roads and labels are transmitted at higher resolutions, while less critical features like water bodies and forests are transmitted at lower resolutions. This local quality approach ensures that bandwidth is allocated efficiently according to the actual visual importance of each geographic feature type.

Inventive Principle:
Principle #3Local quality

2Quantity of substance

If compression is applied to reduce bandwidth usage, then bandwidth efficiency is improved, but image quality deteriorates due to lossy compression artifacts

Engineering Contradiction:
Improvebandwidth usageVSAvoidimage quality
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The map is segmented into multiple layers, allowing different compression strategies to be applied to each layer based on its characteristics. This enables lossless or minimal-loss compression for layers where quality is critical, while allowing more aggressive compression for layers where quality loss is less noticeable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different compression algorithms and compression ratios are applied to different layers based on their visual importance and characteristics. Critical layers like roads and labels use lossless or high-quality lossy compression, while less critical layers like water bodies use more aggressive lossy compression, optimizing the balance between bandwidth usage and perceived image quality.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3391247B1Split tile map rendering
Publication Date: 2023.04.26 GOOGLE LLC
  • EP3391247B1 patent drawingFigure 1
  • EP3391247B1 patent drawingFigure 2A
  • EP3391247B1 patent drawingFigure 2B

AI summary

To efficiently transmit image map data to a client device, a map server selects map data for rendering a digital map of a certain geographic area at the client device and generates multiple map image layers using the selected map data, each covering the geographic area. In particular, the map server generates (i) a first map image layer including a first type of geographic data and having a first resolution, and (ii) a second map image layer including a second type of geographic data and having a second resolution. The map server then transmits the multiple map image layers to the client device via a communication network for generating a single digital map of the geographic area.