Joint special issue


During the conference, three workshops led by respected international experts will be realized.

GNSS positioning using low-cost receivers for pedestrian navigation and mapping applications (Dr. Paolo Dabove, Politecnico di Torino, Italy)

In the last few years some significant advances have been made in the field of positioning using mass-market and portable devices, thanks to the available microtechnology. The spread of miniaturized Global Navigation Satellite System (GNSS) chipsets mounted on many devices like smartphones, with their low-cost production and the microelectronic components miniaturization, have increased the spread of location-based applications and services (LBS), which the user can use to perform numerous spatial related tasks.

Apart from the processing strategy, the performance of a GNSS positioning mainly depends on the quality of the receiver hardware, going from the high-grade dual-frequency geodetic receivers to miniaturized low-cost single-frequency receivers up to GNSS receivers installed on portable devices, like smartphones and tablets. The use of the latter along with free and open source software, with the aim of estimating a precise trajectory allowing up to decimeters level of accuracy, is the focus of this workshop. In particular, the workshop provides an insight into the widespread use of free and open source software (FOSS) for GNSS positioning, focusing the attention on the RTKLIB software and the RTKGPS+ app, both for real-time and post-processing purposes.

Different GNSS positioning techniques will be considered and investigated, starting from post-processing (static and kinematic - PPK) up to real-time (Real Time Kinematic – RTK - and Network Real Time Kinematic - NRTK) methods, trying to give an overview of possible positioning accuracies obtainable using these new interesting devices. A brief overview related to PPP and PPP-RTK positioning techniques will be provided, as an interesting alternative solution for processing strategy using these portable instruments.

We will analyze, acquire and process the data collected from different types of GNSS receivers and we will see how it is possible to use a smartphone as a tool for precise positioning, whether its internal sensor is used for estimating the positioning solution or if it is used as a calculation engine for an external low-cost GNSS receiver. If the hygienic-sanitary and environmental conditions permit, during the workshop we will carry out also a practical experience of data collection.

Visual-Inertial Navigation: Basics and Beyond (prof. Stephan Michael Weiss, Alpen-Adria-Universität Klagenfurt)

At the beginning of the workshop, we discuss the basics of vision based motion estimation and the fundamentals of visual-inertial navigation. After a short introduction, we will focus on two main approaches, loosely and tightly coupled fusion, and discuss benefits and drawbacks of each method. We will further learn that visual-inertial navigation can be done via statistical filtering or through the use of a non-linear optimization methods -- again, both methods have their benefits and drawbacks. With this in mind, we will have a closer look at what states can actually be estimated in such a setup. We will also discuss what states cannot be estimated and the implication of this issue. Some states, such as sensor calibration states like distance and rotation between the camera and the inertial measurement unit require specific motion to be estimated. Focusing on such required motion, we will talk about the so called observability aware motion generation to ensure that an autonomous systems generates informative motion for its state estimation.

With this overview on the aspects of visual-inertial navigation in mind, we will provide an overview of today's visual-inertial motion estimators. We will review the main research directions currently pursued in this area and discuss their advantages and limitations. A focus will be put on their applicability on resource constrained systems as well as their ability to work in visually challenging environments. While the computational complexity seems to be well tackled already in great commercial products, the issue of visually challenging environments continues to keep researchers busy. We discuss one of our latest approaches to demonstrate that even on visually fairly homogeneous surfaces, we can provide visual-inertial motion estimation.

Techniques and Systems for Wi-Fi Positioning (Dr. Günther Retscher (TU Wien, Austria)

Wi-Fi is one of the most widely used signal-of-opportunity for positioning and tracking of mobile users. It is widely adopted for smartphone-based indoor positioning systems due to the availability of already deployed infrastructure for communications. A high number of Access Points of public and private networks are visible guaranteeing a high signal ubiquity. The Wi-Fi signals have therefore a high potential to employ them for numerous applications for localization and guidance. Localization is either based on direct measurements of the Received Signal Strengths (RSS) of the surrounding Wi-Fi Access Points or on the measurement of the Round Trip Time (RTT) between the mobile device and Access Points. Localization methods therefore include lateration and fingerprinting algorithms. Depending on the positioning technique adopted different level of positioning accuracies are achievable. This workshop addresses the most commonly used localization approaches and algorithms. A special emphasis is given on novel approaches for RSS- and RTT-based positioning and their combination and integration into hybrid positioning solutions. The workshop provides an insight into the widespread use of Wi-Fi, such as the use and application for mobile devices, new emerging application fields for localization of mobile users in indoor, urban and transitional environments, Location-based Services (LBS), algorithm developments for these application fields as well as the use of new and traditional technologies based on Wi-Fi for indoor spaces. Several case studies will showcase the major application fields and the research requirements to go ahead.