Mobile Navigation With SVG

Christian Schmitt

SVG Open 2005

Contents

Introduction

Contents

Indoor positioning systems

Pathfinding + Map generator

Map viewer + navigation

Demo

conclusion

Indoor Positioning Technologies Overview

Infrared (IR)

Wireless LAN (WLAN)

Ultra-wide band (UWB)

Hybrid solution

Infrared

Principle/Features

IR beacons sending a specific code. Directed connection. Range: 80-300 cm Accuracy: see range

Advantages

Universal Inexpensive Basic technology

Disadvantages

Line of sight required Does not scale very well Maintenance costs

WLAN

Principle/Features

Fingerprinting based on signal strength measurements

Accuracy: 3-7 meters

Pros

Use of existing WLAN infrastructure Most PDAs have WiFi. WiFi tags Easy to setup Large area covered

Contras

High power consumption of WLAN card Poor update rate Calibration step

Ultra Wide Band

Features

No multipath distortion Time Difference of Arrival, Angle of

Arrival Accuracy: 15cm

Pros

Accuracy Good update rate

Contras

Special hardware Complex Setup

Our hybrid solution

WLAN from Ekahau Inc

Coverage: whole floor Accuracy: 3 meters

UWB from Ubisense

Coverage: single room Accuracy: 20 cm

IR from guideID and Eyeled

Coverage: few emitters in front of pictures

Pathfinding

Introduction

Contents

Indoor positioning systems

Pathfinding + map creation

Map viewer + navigation

Demo

conclusion

SVG Map generation

Problem: the same SVG map will not render on

all platforms

Solution:create a common semantic description

of the map together with transformation rules specific to each platform

Implementation

DTD suitable for room plans User Interface to define a new

map XSLT transformation to output

SVG A XSLT file for each target

platform

The A* algorithm implementation

A* algorithm

Is a graph search algorithm that finds a shortest path from a given initial node to a given goal node

Uses an heuristic to direct the search Cost function is the distance between

two nodes

Implementation

Route computation on client (Windows Mobile 2003)

Implemented using STL library Graph stored as text file

Map viewer

Introduction

Contents

Indoor positioning systems

Pathfinding + helper tools

Map viewer + navigation

Demo

conclusion

Viewer functionalities

Zoom in/out, panning

Display of the current position

Selection of a destination and display of the optimal route

Animations of objects

Support for information browsing on the map

On the search for perfection

First step: Personal Java application rendering raster

bitmap

Drawbacks: Raster bitmap: not scalable, high footprint Java: weak user interface, waste of system

resources, no access to hardware resources

Next step: Native C++ application rendering SVG.

Which SVG viewer to use ?

Which SVG viewer?

Only two native SVG viewers available for Windows Mobile-based PDAs:

eSVG and BitFlash

eSVG

eSVG 1.6 license purchased in Mai 2003

Performance issues Latest version with .NET support

BitFlash

BitFlash SDK license purchased in Spring 2004

Fast rendering and good interaction capabilities

Using BitFlash SDK

Usage guidelines

Create player instance, load document Communication with the player via commands and callback

functions, DOM API Only one thread should access the player at the same time

Example

Zooming in:

BFZoomEvent zoomData;zoomData.fpFactor = 0x7FFF;//0xcccc; // 1.5 in 16.16 fixed point zoomData.iCenterX = (BF_INT16)point.x;zoomData.iCenterY = (BF_INT16)point.y;int dwWait=WaitForSingleObject(hSVGPlayerSemaphore,INFINITE);CheckStatus(BFprocessCommand( pPlayer, BF_COMMAND_VIEW_ZOOM,

&zoomData ));CheckStatus(BFprocessCommand( pPlayer,

BF_COMMAND_VIEW_REDRAW, 0 ));ReleaseSemaphore(hSVGPlayerSemaphore,1,NULL);

Integration of positioning technologies

Ekahau/Ubisense

Server: Middleware server connecting to Ekahau and Ubisense Server, keeping position information up-to-date and delivering position data to clients

Client: Location Thread connects to server, parses messages and refreshes buddy position on map

IR

IR thread is listening on IR port (serial) IR code found => trigger animation

Issues

Refresh rate (only Orinoco cards provide good results)

Integration

Demo

Demo

Conclusion

Positioning

Appropriate combination of positioning systems needed to achieve best tradeoff between quality of service and cost

Indoor navigation is still a very challenging research topic

SVG

SVG maps are perfect for mobile navigation Rendering of SVG maps no longer too slow

Future work

Better navigation : audio output and personalized routes

Seemless integration of positioning systems Tests on Symbian and .NET

Thank you !