What’s SuperNavigation Engine?

Car navigation industry has been boosted by automobile industry and intelligent transportation in the last few years. At present, car navigation system integrates GPS and GIS with the modern computer technology to enable real-time vehicle positioning and intelligent navigation. This greatly increases driving convenience and helps drivers to get to the destination easily.

Car navigation is one of the main GIS applications in mass informationization. SuperNavigation Engine (SNE) is a SuperMap’s car navigation platform and developed for satellite navigation developers. Its functions cover map display, map manipulation, POI query, routing, positioning and navigation, and etc. Those functions are offered in the class libraries in SNE. Additionally, a fully functional navigational application system (SuperNavigation) is available in SNE software package. This system is developed with a Win32 programming language and extendable or customizable.

Figure 5 SuperNavigation Engine	Figure 6 SuperNavigator

SuperNavigation Engine (SNE) is a professional car navigation engine platform developed with SuperMap Universal GIS Core (UGC) and the national standards of electronic map for car navigation application. It offers a fully customizable SDK for developing a car navigation system that can be run on multiple operating systems and multi CPUs in the different IDEs. The basic functions include map display, map operating, POI query, path analysis, position and navigation, and etc. All kinds of navigation solution providers and mobile device manufactures can rapidly customize their own navigation applications or OEM it into all kinds of terminal navigation products.

SNE is composed with 19 modules in three functional levels: fundamental layer, map visual layer and navigational application layer. The relationships are illustrated below, where the universal GIS fundamental modules are in blue color and every other color represents one type of engines:

Figure 7 SNE Architecture

　　◆ Universal GIS fundamental module: Defines fundamental data structure, algorithm, map display flowchart, as well as basic navigational element types. This module is compiled as Basci.dll and Basci.lib.

　　◆ Navigational data engine: the Universal GIS based data engine is responsible for managing the navigational data in NDF format. It provides data source read/write, POI index data query, and etc. This module is compiled as NdfEngine.sdx and NdfEngine.lib.

　　◆ GDI visual engine: the Universal GIS based visual engine displays SNE map data on Windows system. This module is compiled as WGraphics.uge and WGraphics.lib.

　　◆ Fast image engine: reading and displaying SIT (SuperMap Image Tower) image format. This module is compiled as SuSitEngine100.sdx and SuSitEngine100.lib.

　　◆ GPS module: processing GPS signal reception and protocol interpretation, data reading, and ect. This module is compiled as GPS.dll and GPS.lib.

　　◆ Routing engine: providing cross-layer searching among multi-layer road topology network data and implementing the optimal routing. This module is compiled as RouteAnalysis.dll and RouteAnalysis.lib.

　　◆ Navigational engine: providing navigation information during traveling and implementing intelligent vehicle navigating, including voiced tips, 3D roundabout magnification, and etc. This module is compiled as GuideEngine.dll and GuideEngine.lib.

Technical Features

Modular Architecture Design

SNE’s modular architecture can provide the different navigation functions to different engine modules. Every engine can be distributed in the class library, and also the logical relationships of engines are relatively independent. The engines can be collaborated with each other and divided flexibly to function independently. This structural model makes the whole system management easily and allows users to customize some of the application engines (e.g. GPS module, route analysis module), therefore, it meets the various developing needs for car navigation applications.

Cross Platform Development

SNE is developed with Universal GIS architecture, which is a brand new technical architecture designed by SuperMap. The fundation of Universal GIS is to separate all GIS functionalities and algorithms from the information technologies provided by the sophisticated software architecture design. The pith of Universal GIS is to establish a universal GIS core (UGC) for implementing the core GIS functionalities, which are relatively unchangable or not affected by the rapid technical change. With UGC, any change can be easily adapted by just implementing or adjusting peripheral modules and user interface. This will extend the application's life cycle and reduce a lot of repetitive investment due to the technical change. Universal GIS is an ideal software architecture that supports any existing computing device, operating system, programming language, database as well as data formats.

SNE, developed with a concise Universal GIS class library, fully utilizes cross platform, multiple environments, and the other technical features. Regarding to the limited hardware resources of the Mobile devices, UGC maks the core of SNE concise and efficient. Therefore, the navigation application developed with SNE platform, can exert technical advantages on different OS, hardware, programming languages or IDEs; the user can just focus on maintaining and updating of the peripheral functionalities.

Figure 8 SNE Integrated Developing Environments

Open Architecture Design

Considering users’ needs for customization, SNE provides a number of opened functions to meet user's requirements. For example, SNE opens workspace file to users so that the customizable map color scheme is available to obtain various visual effects; in the routing engine, the users are allowed to overload route searching classes to implement their customized route searching.

Multi-threading Map Rendering

Due to the limited hardware capability on the mobile device (e.g. PDA), it will take a considerable amount of time to process the large amount of data and display the map. Sometime, the map might flash quite often. To tackle this problem, the map display of SNE employs multiple threading and dual cache techniques.

Figure 9 Multi-threading map rendering (with symbols)	Figure 10 Multi-threading map rendering (without symbols)

With the Multiple threading, an application can undertake multiple tasks. For a single threaded CPU, only one thread is working in a given time period. If more tasks are desired to be processed at the same time, the multi-threading technique is needed. A time slice is allocated to a thread, thus allowing switching among different threads according to the certain strategies. As the time slice is very short, the user feel that multiple tasks are simultaneously executed. Therefore, multi-threading can obviously reduce latency and enhance user experiences.

Dual cache refers to a technique that the images are firstly created on RAM, and presented from the memory to the screen. With this technique, the screen flash can be effectively minimized and the visual effect is enhanced also.

Efficient Indexing Algorithm

Point of Interest (POI) has much attribute information within the massive data. A number of indexing methods are available for accessing the attribute data. The data structure of indexing is tighten; the algorithm of indexing has been optimized; the index data expanding problem is resolved efficiently for querying millions of POI in real time. Five basic POI query modes are provided in SNE.

Hierarchical Fast Search

For any navigation software, the precision and efficiency of routing are important indicators. The routing engine of SNE is developed with the road network model specified by the National Standards of Application Storage Format for Digital Map in Vehicle Navigation System. With multi-scale, multi-mode, and adaptive seamless hierarchical fast search techniques, the real-time analysis of large scale road network (million grades) is implemented, and the analysis results can match actual road status maximally.

Dead Reckoning

Positioning technology is a foundation of the intelligent navigation. Its precision and real-time ability directly affects the usability and overall performance of a car navigation application. When ever the GPS signal is too weak to be received, this dead reckoning technique can infers to the current position of a vehicle based upon the previous traveling tracks. GPS and DR are combined together in SNE to ensure precision and continuous positioning and navigation in various environments.

Dynamic 3D Synthesis Magnification of Road Junction

The conventional navigation software uses either 2D road view or static 3D texture presentation for road junction magnification. The former method can not provide the good visual effect while the latter one increases the software size to provide a large number of magnified images. Conversely, SNE employs OpenGL to dynamically synthesize 3D magnification of a road junction in real time according to the actual road status, thus resulting in a vivid effect and enhancing users’ visual experience.

Figure 11 Dynamic 3D junction guiding	Figure 12 3D Junction guiding in full screen mode

Smart Driving Tip Synthesis

SNE adopts smart driving tip synthesis to avoid frequent reading driving tips from the GPS device screen. According to the road and vehicle status, the road junction mode is automatically analyzed with filtering out the unnecessary data, and then the driving tips are synthesized to offer a more precise, humanized, and safer navigation message.

Rapid Application Development

SNE provides a professional data compiling service for users to cope with massive data and effectively reduce developing difficulty; SNE offers a complete application framework for users to build their professional navigation application rapidly. With the user manuals, sample codes, and developing guidelines, the developers can quickly start navigation application development.

Main Functionalities

Basic Map Operation

SNE delivers complete map display and operation functions for navigation applications, including many map visual effects, extensible vector symbol libraries, conventional/multi-threading map zooming, panning, full extent displaying, rotation, and etc.

SIT is SuperMap’s exclusive fast image pyramid technique that can capable of handle massive image data compression and presentation. SIT is introduced into SNE for real-time GB level image presentation.

Figure 13 Visual effect of SIT

POI Search

Five basic POI index query methods, full text, address, alphabet, telephone and around are available in SNE. The users can combine these indexes to achieve the advanced user-defined search.

Figure 14 POI Index query mode

Routing

SNE routing engine complies with the national standard for road network model with hierarchical fast search technique for real-time analysis of large scale road network status. Its main features include:

Million grade real-time road network analysis
Support for complex traffic rules related to time, car model, lane, and etc.
Options available for avoiding traffic jam or accident spot
Preset five route searching options: Fastest Route, Shortest Route, and Highway Priority, Avoid Highways, and Recommended Route (high level road and landscape road preferred). Below is a comparison between Fastest Route and Avoid Highway routes with the same starting point and ending point.

Figure 15 Fastest route	Figure 16 Avoid highway route

User defined route search option for flexible routing
Considering the impact of both search speed and precision on route plan, four route search strategies are available. They are synthesis search (synthesize multiple level networks searching), fast search (speed searching with upper level of road networks), precise search (route searching with all level of networks), and realized search (route searching with consideration of real time transport information)

Provide two route recovery modes: simplified route recovery mode – the roads inside the complex junctions (crossroads, loop island etc.) are not recovered; precise route recover mode – all roads are recovered.

GPS / DR Positioning

Vehicle positioning is the base of the intelligent navigation. Its precision directly impacts the usability and performance of the navigation software. SNE combines GPS and Dead Reckoning technologies to ensure the availability of positioning and navigation for various signal situations.

With the combination of GPS and DR, the precise positioning will correct the error of DR when the GPS signal is strong. This avoids accumulating errors caused from DR. Whenever the GPS signal temporarily unavailable or so weak, the corrected DR will ensure the vehicle positioning in the certain time period.

Rectifying Deviation and Matching

Rectifying deviation and Matching is the technology to match the vehicle position data output from GPS/DR with the detailed road data in digital map. After confirming that the vehicle position does not deviate or is in stillness status, the vehicle position is matched to the most possible matching road. By combining intelligent map matching and GPS/DR, the positioning information can synchronize ambient information to correct deviation and enhances the overall accuracy of the positioning.

Voice Guidance

SNE voice navigation adopts intelligent synthesis technology with real human voice.