James D. Carswell

Investigating ultrasonic positioning on mobile phones

In this paper we evaluate the innate ability of mobile phone speakers to produce ultrasound and the possible uses of this ability for accurate indoor positioning. The frequencies in question are a range between 20 and 22 KHz, which is high enough to be inaudible but low enough to be generated by standard sound hardware. A range of tones is generated at different volume settings on several popular modern mobile phones with the aim of finding points of failure. Our results indicate that it is possible to generate the given range of frequencies without significant distortions, provided the signal volume is not excessively high. This is preceded by the discussion of why such ability on off-the-shelf mobile devices is important for Location Based Services (LBS) applications research. Specifically, this ability could be used for indoor sound trilateration positioning. Such an approach is uniquely characterized by the high accuracy inherent to sound trilateration, with little computational burden on the mobile device, and no specialized hardware or audible noise. Combined with a fast internet connection and other sensors present in modern smartphones, such as accelerometers and magnetometers, our approach confirms mobile phones as a suitable platform for indoor LBS applications.

An environment for content-based image retrieval from large spatial databases

In this paper, we address the problem of content-based image retrieval using queries on shape and topology. We focus on the particularities of image databases encountered in typical topographic applications and present the development of a spatial data management system that enables such queries. The query requires user-provided sketches of the shape and spatial configuration of the object (or objects) which should appear in the images to be retrieved. The objective of the search is to retrieve images that contain a configuration of objects sufficiently similar to the one specified in the query. Our approach combines the design of an integrated database with the development of a feature library and the necessary matching tools. In this paper, we present our overall scheme, introduce some individual database components, and provide some implementation results.

Scale and Orientation-invariant Scene Similarity Metrics for Image Queries

In this paper we extend our previous work on shape-based queries to support queries on configurations of image objects. Here we consider spatial reasoning, especially directional and metric object relationships. Existing models for spatial reasoning tend to rely on pre-identified cardinal directions and minimal scale variations, assumptions that cannot be considered as given in our image applications, where orientations and scale may vary substantially, and are often unknown. Accordingly, we have developed the method of varying baselines to identify similarities in direction and distance relations. Our method allows us to evaluate directional similarities without a priori knowledge of cardinal directions, and to compare distance relations even when query scene and database content differ in scale by unknown amounts. We use our method to evaluate similarity between a user-defined query scene and object configurations. Here we present this new method, and discuss its role within a broader image retrieval framework.

An environment for mobile context-based hypermedia retrieval

This paper proposes a novel solution to querying hyperlinked multimedia cultural heritage datasets based on the users context. Context in this sense is defined as the users location in virtual space and the particular mobile device being modeled together with user preferences or profile. The purpose is to automatically push relevant data from the database server to the client based on this comprehensive definition of the users context. Consideration in regard to which mobile device is currently being modeled is a primary filter for determining what data will be sent and in what format. For example, image data will not be sent to a mobile phone and video will not be sent to a PDA. The CHI (Cultural Heritage Interfaces) project differs from many of the models encountered on the Web in that its primary focus is not the accurate 3D rendering of a street/landscape, but the simulation of such a physical reality to explore the adaptive hypermedia paradigm in the context of a spatial navigation interface.

Touch2Query enabled mobile devices: a case study using openstreetmap and iphone

This paper describes our mobile spatial interaction (MSI) prototype Touch2Query which presents the idea of using the touch screen on mobile devices to assist in performing ad-hoc spatial queries. This approach differs from conventional mobile LBS applications where the query shape (search space) is limited to either a bounding box or radius. Instead, we provide functionality that allows users to interactively draw any desired query shape overlaid on an area of interest directly on a mobile device with their finger by combining vector primitives such as circles, polygons, polylines, and points. With the help of location and orientation aware mobile devices, mobile maps, and real-time distance and area measurements, Touch2Query gives the users freedom to perform customised spatial queries on objects/areas of interest while realising a better contextual understanding of their spatial environment at the same time.

Digital Image Similarity for Geo-spatial Knowledge Management

The amount and availability of high-quality geo-spatial image data, such as digital satellite and aerial photographs, is increasing dramatically. Task-based management of such visual information and associated knowledge is a central concern for organisations that rely on digital imagery. We are developing geo-spatial knowledge management techniques that employ case-based reasoning as the core methodology. In order to provide effective retrieval of task-based experiences that center around geo-spatial imagery, we need to forward novel similarity metrics for directly comparing the image components of experience cases. Based on work in geo-spatial image database retrieval, we are building an effective similarity metric for geo-spatial imagery that makes comparisons based on derived image features, their shapes, and the spatial relations between them. This paper gives an overview of the geo-spatial knowledge management context, describes our image similarity metric, and provides an initial evaluation of the work.

Mobile Visibility Querying for LBS

This article describes research carried out in the area of mobile spatial interaction (MSI) and the development of a 3D mobile version of a 2D web-based directional query processor. The TellMe application integrates location (from GPS, GSM, WiFi) and orientation (from magnetometer/accelerometer) sensor technologies into an enhanced spatial query processing module capable of exploiting a mobile devices position and orientation for querying real-world spatial datasets. This article outlines our technique for combining these technologies and the architecture needed to deploy them on a sensor enabled smartphone (i.e. Nokia Navigator 6210). With all these sensor technologies now available on off-the-shelf devices, it is possible to employ a mobile query system that can work effectively in any environment using location and orientation as primary parameters for directional queries. Novel approaches for determining a users visible query space in three dimensions based on their line-of-sight (ego-visibility) are investigated to provide for “hidden query removal” functionality. This article presents demonstrable results of a mobile application that is location, direction, and orientation aware, and that retrieves database objects and attributes (e.g. buildings, points-of-interest, etc.) by simply pointing, or “looking”, at them with a mobile phone.

EgoViz --- A Mobile Based Spatial Interaction System

This paper describes research carried out in the area of mobile spatial interaction and the development of a mobile (i.e. on-device) version of a simulated web-based 2D directional query processor. The TellMe application integrates location (from GPS, GSM, WiFi) and orientation (from digital compass/tilt sensors) sensing technologies into an enhanced spatial query processing module capable of exploiting a mobile devices position and orientation for querying real-world 3D spatial datasets. This paper outlines the technique used to combine these technologies and the architecture needed to deploy them on a sensor enabled smartphone (i.e. Nokia 6210 Navigator). With all these sensor technologies now available on one device, it is possible to employ a personal query system that can work effectively in any environment using location and orientation as primary parameters for directional queries. In doing so, novel approaches for determining a users query space in 3 dimensions based on line-of-sight and 3D visibility (ego-visibility) are also investigated. The result is a mobile application that is location, direction and orientation aware and using these data is able to identify objects (e.g. buildings, points-of-interest, etc.) by pointing at them or when they are in a specified field-of-view.

Sketch-Based Image Queries in Topographic Databases

In this paper we present the development of a system prototype for sketch-based queries for the content-based retrieval of digital images from topographic databases. We discuss our overall strategy and associated algorithmic and implementation aspects, and we present associated database design issues. The query tools devised in this research are employing user-provided sketches of the shape and spatial configuration of the object(s) which should appear in the images to be retrieved. Our matching tool is inspired by least-squares matching (lsm) and represents an extension of lsm to function with a variety of raster representations. Our strategy makes use of a hierarchical organization of feature shapes within a feature library. The results are ranked according to statistical scores and the user can subsequently narrow or broaden his/her search according to the previously obtained results and the purpose of the search. Our approach combines the design of an integrated database environment with the development of a feature library and the necessary matching tools. We discuss our overall strategy and individual database components and present some implementation results.

Asynchronous ultrasonic trilateration for indoor positioning of mobile phones

In this paper we discuss how the innate ability of mobile phone speakers to produce ultrasound can be used for accurate indoor positioning. The frequencies in question are in a range between 20 and 22 KHz, which is high enough to be inaudible by humans but still low enough to be generated by todays mobile phone sound hardware. Our tests indicate that it is possible to generate the given range of frequencies without significant distortions, provided the signal volume is not turned excessively high. In this paper we present and evaluate the accuracy of our asynchronous trilateration method (Lok8) for mobile positioning without requiring knowledge of the time the ultrasonic signal was sent. This approach shows that only the differences in time of arrival to multiple microphones (control points) placed throughout the indoor environment is sufficient. Consequently, any timing issues with client and server synchronization are avoided.