WORKSHOP REPORT

Report on the Sixth International Workshop onLocation and the Web (LocWeb 2016)
Dirk Ahlers1 and Erik Wilde2
1

NTNU – Norwegian University of Science and Technology, Trondheim, Norway,
dirk.ahlers@idi.ntnu.no2
CA Technologies, Zürich, Switzerland, dret@ca.com

Abstract
For describing and understanding the real world, location is an important factor. Consequently, it also appears in many Web applications and mining approaches as a crosscutting issue. LocWeb 2016 continues a workshop series addressing issues at the intersection of location-based services and Web architecture and was held at WWW 2016. It
combines geospatial search, information management, and Web architecture, with a main
focus on location-aware information access. The workshop drew contributions from various
fields, ranging from mobility analytics over new ways to understand cities to Web standards.
LocWeb2016 had an interdisciplinary combination of contributions, with two keynotes andthree long papers. We will briefly discuss the workshop theme and the contributions.

1

Introduction

Location has quickly moved into the mainstream of the (mobile) Web. It also continues tobe a strong driver of applications and research activities. After the initial boost and consolidation of approaches based on the simple use of geospatial coordinates, we now see anincreasing demand for more sophisticated location-based services, involving more powerfulmechanisms in terms of information retrieval, mining, analytics and semantics. New application areas for Web architecture, such as the Internet of Things (IoT) and the Web of Things(WoT), also mean that there will be increasingly rich and large sets of resources for which
location is highly relevant.
Following the successful LocWeb workshops in 2008, 2009, 2010, 2014, and 2015, LocWeb
2016 continues the workshop series, addressing issues at the intersection of location-based
services and Web architecture. Its focus lies in Web-scale systems and services facilitating
location-aware information access. The location topic is understood as a cross-cutting issue equally concerning Web information retrieval, semantics and standards, and Web-scale
systems and services.
LocWeb 2016 is the sixth event in the workshop series and took place on April 11th, 2016
in Montréal, Canada, co-located with WWW2016, the 25th International World Wide Web
Conference, which was held in the Palais des Congrès (geo:45◦ 30’N;73◦ 34’W).

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LocWeb is an integrated venue where the location aspect is discussed in depth within
an interdisciplinary community. It is also highly interactive and collaborative, with ample
room for discussion and demos that explore and advance the geospatial topic in its various
relevant areas. The workshop helps advancing the integration of the geospatial dimension
into the Web, and promotes challenging research questions.
Details, including most of the presentations made at the workshop and information about
previous editions, can be found on the workshop homepage1 and on the workshop series
homepage2 . The LocWeb report for 2015 has been previously published in SIGIR Forum [2]as well as those for previous years.

2Workshop Theme and Topics

LocWeb solicited submissions under the main theme of Web-scale Location-Aware Information Access. Subtopics included (i) geospatial semantics, systems, and standards; (ii) largescale geospatial and geo-social ecosystems; (iii) mobility; (iv) location in the Internet/Webof Things; and (v) mining and searching geospatial data on the Web. The workshop encouraged submissions describing Web-mediated or Web-scale approaches that build on reliable
foundations, and that thoroughly understand and embrace the geospatial dimension.
The workshop’s topics of interest were: Location-Aware Information Access, LocationAware Web-Scale Systems and Services, Location in the Internet/Web of Things, Large-scale
Geospatial Ecosystems, Standards for Location and Mobility Data, Location in Unstructuredand Semi-Structured Information Sources, Location Semantics, Modeling Location and Location Interaction, Geo-Social Media and Systems, Location-Based Social Networks, Geospatial
Web Search and Mining, Visual Analytics of Geospatial Data on the Web, Location-BasedRecommendation, Geo-Crowdsourcing, Mobile Search and Recommendation.

3Workshop Contributions

We had an interdisciplinary combination of contributions at LocWeb 2016, with one researchkeynote, one standards keynote and three full papers.

3.1

Keynotes

The first keynote was given by Luca Aiello, who talked about The Sensorial Map of theCity [4]. The keynote discussed the broad human sensorial range that can be used for urban
studies, furthering a theme from last years’ keynote. Apart from the classical sense of sight,
Luca discussed sound and smell as important aspects of a cityscape. While difficult to capture
in real life, he showed an approach that uses data containing implicit perceptions of soundand smell from social media to draw new kinds of urban maps, thus adding a new factor tolocation characteristics mined from Web sources.
A second keynote titled GeoJSON Update was given by Erik Wilde, which was an update
about the ongoing standardization effort for the GeoJSON format. GeoJSON moved frombeing a community standard to establishing an IETF working group, which was working on12

http://dhere.de/locweb2016/
http://dhere.de/locweb/

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the specification text until mid 2016. In the meantime GeoJSON has been published by theIETF as RFC 7946 [6].

3.2Paper Presentations

The workshop accepted 3 full papers. Due to a very diligent PC, we had over 5 reviews
per paper on average which led to an overall acceptance rate of 60%. We had internationalauthor groups from Europe and Asia, but this time there were no cross-country authorships.
Full papers had 20 minutes of presentation and 10 minutes of time for discussion. The
proceedings [3] are available in the ACM Digital Library3 and also from the conference
page4 , as part of the WWW 2016 Companion. Slides for all papers are available from theworkshop homepage.
The first paper was by Hakan Bagci and Pinar Karagoz about Context-Aware Friend
Recommendation for Location Based Social Networks using Random Walk [5]. It discussed apersonalized recommendation approach for Location-based Social Networks (LBSNs). Subgraph analysis is used to link locations, users, and relationships and a ranking approachbased on random walks delivers friend recommendations based on a user’s context. Theirapproach considers social, personal, and spatial contextto consider popularity, expertise, andmultiple degrees of friendship. The evaluation shows that the recommender can outperform
good baselines and is stable over various datasets.
Lisette Espı́n Noboa presented a joint paper with Florian Lemmerich, Philipp Singer andMarkus Strohmaier titled Discovering and Characterizing Mobility Patterns in Urban Spaces:
A Study of Manhattan Taxi Data [8]. The work focuses on discovering and explaining spatiotemporal mobility patterns by combining both non-negative tensor factorization (NTF) forclustering and HypTrails, a Bayesian approach for hypotheses generation based on previous
work of their group. They use openly available data in the form of the well-known Manhattan
taxi data set together with census and foursquare data The combined approach allows totest different mobility hypotheses generated from three categories and derive explanations
for the specific type of mobility patterns existing within taxi rides. The work shows a goodtheoretical grounding and very thorough evaluation, arguing for more granular mobility
analysis to better understand spatio-temporal patterns.
Peter Rushforth presented a paper on Maps for HTML: A New Media Type and Prototype
Client for Web Mapping [11]. The main argument in this paper is that in the same way asbrowsers have started to incorporated other previously add-on based functionality such asvideo and audio, the same might happen for Web maps. Browser-based maps are ubiquitousin today’s Web, and yet browsers themselves are still fundamentally unaware of location andmapping as a concept (apart from the very limited Geolocation API [9], with a new but stillrather limited version being proposed [10]). The solution presented uses HTML5 custom elements [7] as their current implementation foundation, but could also be natively implemented
by browsers. Rushforth participates in the Maps For HTML Community Group (CG) 5 whichaims at creating a draft that would become part of the general HTML5 landscape.
3

http://dl.acm.org/citation.cfm?id=2872518&picked=prox
http://www2016.net/proceedings/forms/companion.htm#95
https://www.w3.org/community/maps4html/
4

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4Discussion Session

This discussion session was started by the organizers with an introduction of location-relatedcharacteristics of the hosting city. This was to highlight the highly local and specific usesof location and of place and how this can lead to location being highly context- and citydependent.
One interesting peculiarity about Montreal from the LocWeb viewpoint is that is contains the so-called Underground City (La Ville Souterraine or RÉSO in French). This is atunnel network that connects buildings and subway stations within a large part of downtown Montreal. It could be more accurately called an indoor city as it is not fully separated
underground, but uses a tunnel system to connect both underground places and also open
malls and public buildings with atrium structures starting in the basement. An impression
is given in Fig. 1 with maps of the structure available on the Web6 .
Montreal shares this with some other Canadian cities – for example Toronto PATH –and also some other places around the world that have extensive underground structuresthat not only concern one building, but form an underground network. This “city below”
does not necessarily follow the same network structure similar of the road network of thecity above because it is mostly pedestrian in nature and so often incorporates paths throughbuildings, as can also be seen in the Montreal example in Fig. 1. Structures can also beoverground, such as the Calgary +15 covered skywalk or the Central Elevated Walkway inHong Kong, that create a pedestrian bridge network connecting buildings for easier accessby pedestrian on top of traffic. Tunnels, bridges, or skywalks appear in many cities, andin these examples, the structures are in large parts open and accessible. There is anotherclass that are not open to the general public, such as bridges between office buildings orutility and transport tunnels between hospital or university buildings. Then there is also theaspect of out-of-bounds, fenced off, or abandoned structures, giving rise to the subcultureof urban explorers7 or the guild of trespassers8 . Such structures may not even be mapped atall. One motivation for structures such as RESO can be to get out of the cold or get out of
the heat; but also to connecting vast public transport networks such as underground metrostations. There was a previous discussion at LocWeb2014 about how Tokyo subway stations
are dubbed dungeons, both in reference to RPGs (role playing games) and the difficulty innavigating them or using mobile local search in them, for example due to the lack of GPS
signals, prominent landmarks, or good maps.
Such urban overlapping structures [1] and the complexities of 3D structures in an often
still 2D mapping mindset provide a number of interesting challenges to the LocWeb topic.
There are challenges for navigation that needs all pathways and connections mapped andneeds to develop stronger towards a combination of outdoor and indoor mapping and also for
local search in the extraction and presentation of results that are not at default level. On ausual map, POIs may be overlapped by, e.g., a street and need to be represented accordingly;
on the other hand, identifying and extracting location references to a specific place withina large indoor or underground structure is significantly more difficult that extracting anaddress, with geocoding being an additional issue.
Another topic of discussion that was raised concerned the granularity of location infor6

http://ville.montreal.qc.ca/pls/portal/docs/page/arrond_vma_fr/media/documents/vm_carte_reso.pdf
7
http://weburbanist.com/category/global/urban-exploration/8
http://wiki.lspace.org/mediawiki/Trespassers’_Society

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Figure 1: Underground City views: Atrium of Complexe Desjardins; view from Complexe Desjardins towards Complexe Guy-Favreau with the tunnel crossing under Boulevard René-Lévesque;map of RESO
mation, issues in making sense of patterns as well as bias in datasets that can be hard todetect. Another point in line with the workshop topics was the use of Web standards forpresentation and also extraction of location information.

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5Conclusion and Future Directions

LocWeb2016 had a broad variety of contributions, reflecting the cross-cutting issue of locationon the Web, reaching from standards over varied analysis approaches to rich applications.
WWW2016 was a good conference to hold this workshop. We could reach many interested
and interesting participants from industry and academia and the conference itself also hosted
some additional papers discussing increasingly complex location models as an important partof the approach. The workshop showed again that location is still a complex and rich topic to
be further analyzed and developed and we are looking forward to more exciting contributionsin this field.

Acknowledgements
We would like to thank the authors of submitted papers for their efforts, and all attendeesof LocWeb 2016 for making this an interesting and interactive workshop. We speciallythank Luca Aiello for his keynote. A very special thanks goes to our co-organizer Bruno
Martins from University of Lisbon, Portugal. We are especially grateful to the members of
the program committee for their hard work in reviewing the contributions and providing
substantial feedback on a tight deadline:
Andreas Henrich, Universität Bamberg, Germany; Arjen de Vries, CWI, Netherlands;
Bruno Martins, University of Lisbon, Portugal; Carsten Keßler, CUNY, USA; Chandan Kumar, University Koblenz-Landau, Germany; Christoph Trattner, Graz University of Technology, Austria; Christopher Jones, Cardiff University, UK; Claudia Hauff, Delft University, Netherlands; Clodoveu Davis, Universidade Federal de Minas Gerais, Brazil; DirkAhlers, NTNU, Norway; Erik Wilde, Siemens, USA; Francisco López-Pellicer, Universidad
Zaragoza, Spain; Massimiliano Ruocco, Telenor Research, Norway; Max Egenhofer, University of Maine, USA; Rainer Simon, AIT Austrian Institute for Technology; Ross Purves, Universität Zürich, Switzerland; Steven Schockaert, Cardiff University, UK; Torsten Suel, NewYork University, USA; Vanessa Murdock, Bing, USA; Yana Volkovich, Centro Tecnológicode Catalunya, Spain.
Finally, we would like to thank the organizers of WWW2016 for hosting the workshop,
as well as ACM and Sheridan for their support.

References[1] Dirk Ahlers. Search and Navigation in Complex Overlapping Urban Spaces. In
Making Places Workshop @ NordiCHI2014, 2014.
[2] Dirk Ahlers, Erik Wilde, and Bruno Martins. Report on the Fifth Workshop
on Location and the Web (LocWeb 2015). SIGIR Forum, 49(2):123–128, 2015.
[3] Dirk Ahlers, Erik Wilde, and Bruno Martins, editors. LocWeb ’16: Proceedingsof the 6th International Workshop on Location and the Web, WWW 2016 Companion.
International World Wide Web Conferences Steering Committee, 2016.
[4] Luca Maria Aiello. The Sensorial Map of the City. In Ahlers et al. [3], pages
529–529.

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[5] Hakan Bagci and Pinar Karagoz. Context-Aware Friend Recommendation forLocation Based Social Networks using Random Walk. In Ahlers et al. [3], pages
531–536.
[6] Howard Butler, Martin Daly, Allan Doyle, Sean Gillies, Tim Schaub,and Stefan Hagen. The GeoJSON Format. Internet RFC 7946, August 2016.
[7] Domenic Denicola. Custom Elements. World Wide Web Consortium, WorkingDraft WD-custom-elements-20161002, October 2016.
[8] Lisette Espı́n Noboa, Florian Lemmerich, Philipp Singer, and MarkusStrohmaier. Discovering and Characterizing Mobility Patterns in Urban Spaces:
A Study of Manhattan Taxi Data. In Ahlers et al. [3], pages 537–542.
[9] Andrei Popescu. Geolocation API Specification. World Wide Web Consortium,Recommendation REC-geolocation-API-20131024, October 2013.
[10] Andrei Popescu and Steve Block. Geolocation API Specification Level 2. World
Wide Web Consortium, Working Draft WD-geolocation-API-v2-20111201, November
2011.
[11] Peter Rushforth. Maps for HTML: A New Media Type and Prototype Client forWeb Mapping. In Ahlers et al. [3], pages 543–548.

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