Computational Aspects: How Landmarks Can Be Observed, Stored, and Analysed - Landmarks: GIScience for Intelligent Services - page 146

Tabl e 5. 5 The five most prominent landmarks of the world and for some well known cities,
according to the approach by [ 5 ]
1st

2nd 3rd 4th 5th

World Eiffel Trafalgarsquare Tatemodern Bigben Notredame

New York Empirestatebuilding Timessquare Rockefeller Grandcentralstation Applestore

London Trafalgarsquare Tatemodern Bigben londoneye Piccadilycircus

Rome Colosseum Vaticano Pantheon fontanaditrevi Basilica

Berlin Brandenburgertor Reichstag Potsdamerplatz Berlinerdom Tvtower

Photos taken with digital cameras may contain much more information than
just the image itself. The Exchangeable image file format (Exif) standard
specifies the format for images, as well as for sound and tags, used by digital
cameras, including those in smart phones. This information encompasses the
camera type and basic information about how the image was taken, namely,
exposure, aperture and focal length, but also the date it was taken, the (GPS)
position it was taken at (if the camera allows for this), the photo's resolution,
the color space, the ISO setting, aspect ratio, the software used in the camera,
and much more. In addition, today's photo websites store information about
who has uploaded a photo (the user, either by name or ID), when it was
uploaded, and which digital album it is contained in. Furthermore, these
sites allow users to describe their photos by comments and/or tags. Tags are
freeform keywords associated with an element—here a photo. Typically, users
are free to choose whatever content they like in their tags.

Crandall et al. [ 5 ] may have presented the most advanced attempt to mine such
digital photograph collections. Their approach can deal with millions of photos. The
authors are able to identify the most representative images for the most prominent
landmarks of the largest US or European cities, and to track photographers through
a city, for example. This approach exploits the so called scale of observation ,i.e.,
the fact that on different levels of scale different effects are observable. Observing
on the scale of countries, cities will appear as clusters, when observing on the scale
of a single city, points of interest and tourist attractions will emerge.
Using an estimate of the scale, latitude / longitude values of the photos' locations
are treated as points in a plane and clustered by the mean shift technique. This
technique yields peaks in the distribution of photos. The magnitude of these peaks
represents the number of different photographers that took a photo at this location.
Tab le 5.5 shows some results for different cities. The labels are automatically
generated by picking the top tag within a cluster according to TFIDF.