1,783 research outputs found
Hotels-50K: A Global Hotel Recognition Dataset
Recognizing a hotel from an image of a hotel room is important for human
trafficking investigations. Images directly link victims to places and can help
verify where victims have been trafficked, and where their traffickers might
move them or others in the future. Recognizing the hotel from images is
challenging because of low image quality, uncommon camera perspectives, large
occlusions (often the victim), and the similarity of objects (e.g., furniture,
art, bedding) across different hotel rooms.
To support efforts towards this hotel recognition task, we have curated a
dataset of over 1 million annotated hotel room images from 50,000 hotels. These
images include professionally captured photographs from travel websites and
crowd-sourced images from a mobile application, which are more similar to the
types of images analyzed in real-world investigations. We present a baseline
approach based on a standard network architecture and a collection of
data-augmentation approaches tuned to this problem domain
Where was that photo taken? : deriving geographical information from image collections based on temporal exposure attributes
This paper demonstrates a novel strategy for
inferring approximate geographical information from the
exposure information and temporal patterns of outdoor
images in image collections. Image exposure is reliant on
light and most photographs are therefore taken in daylight
which again depends on the position of the sun. Clearly, the
sun results in different lighting conditions at different
geographical location and at different times of the day, and
hence the observed intensity patterns can be used to deduce
the approximate location of the photographer at the time
the photographs were taken. Images taken inside or at night
are temporally connected to the daylight images and the
geographical information can therefore be transferred to
related ‘‘dark’’ photographs. The strategy is efficient as it
only considers meta information and not image contents.
Large databases can therefore be indexed efficiently.
Experimental results demonstrate that the current approach
yields a longitudinal error of 15.7 and a latitudinal error of
30.5 for authentic image collections comprising a mixture
of outdoor and indoor images. The strategy determined the
correct hemisphere in all the tests. Although not as accurate
as GPS receiver, the geographical information is sufficiently
detailed to be useful. Applications include
improved image retrieval, image browsing and automatic
image tagging. The strategy does not require a GPS
receiver and can be applied to the existing digital image
collections
Determining the Geographical Location of Image Scenes based on Object Shadow Lengths
Many studies have addressed various applications
of geo-spatial image tagging such as image retrieval,
image organisation and browsing. Geo-spatial image
tagging can be done manually or automatically with GPS
enabled cameras that allow the current position of the
photographer to be incorporated into the meta-data of an
image. However, current GPS-equipment needs certain time
to lock onto navigation satellites and these are therefore not
suitable for spontaneous photography. Moreover, GPS units
are still costly, energy hungry and not common in most
digital cameras on sale. This study explores the potential of,
and limitations associated with, extracting geo-spatial
information from the image contents. The elevation of the
sun is estimated indirectly from the contents of image
collections by measuring the relative length of objects and
their shadows in image scenes. The observed sun elevation
and the creation time of the image is input into a celestial
model to estimate the approximate geographical location of
the photographer. The strategy is demonstrated on a set of
manually measured photographs
A Simple Content-based Strategy for Estimating the Geographical Location of a Webcam
This study proposes a strategy for determining the approximate geographical location of a webcam based on a sequence of images taken at regular intervals. For a time-stamped image sequence spanning 24 hours the approximate sunrise and sunset times are determined by classifying images into day and nighttime images based on the image intensity. Based on the sunrise and sunset times both the latitude and longitude of the webcam can be determined. Experimental data demonstrates the effectiveness of the strategy
Mariner Mars 1971 optical navigation demonstration
The feasibility of using a combination of spacecraft-based optical data and earth-based Doppler data to perform near-real-time approach navigation was demonstrated by the Mariner Mars 71 Project. The important findings, conclusions, and recommendations are documented. A summary along with publications and papers giving additional details on the objectives of the demonstration are provided. Instrument calibration and performance as well as navigation and science results are reported
Discovering Latent Clusters from Geotagged Beach Images
Abstract. This paper studies the problem of estimating geographical locations of images. To build reliable geographical estimators, an impor-tant question is to find distinguishable geographical clusters in the world. Those clusters cover general geographical regions and are not limited to landmarks. The geographical clusters provide more training samples and hence lead to better recognition accuracy. Previous approaches build geographical clusters using heuristics or arbitrary map grids, and can-not guarantee the effectiveness of the geographical clusters. This paper develops a new framework for geographical cluster estimation, and em-ploys latent variables to estimate the geographical clusters. To solve this problem, this paper employs the recent progress in object detection, and builds an efficient solver to find the latent clusters. The results on beach datasets validate the success of our method.
Cataloging Public Objects Using Aerial and Street-Level Images – Urban Trees
Each corner of the inhabited world is imaged from multiple viewpoints with increasing frequency. Online map services like Google Maps or Here Maps provide direct access to huge amounts of densely sampled, georeferenced images from street view and aerial perspective. There is an opportunity to design computer vision systems that will help us search, catalog and monitor public infrastructure, buildings and artifacts. We explore the architecture and feasibility of such a system. The main technical challenge is combining test time information from multiple views of each geographic location (e.g., aerial and street views). We implement two modules: det2geo, which detects the set of locations of objects belonging to a given category, and geo2cat, which computes the fine-grained category of the object at a given location. We introduce a solution that adapts state-of-the-art CNN-based object detectors and classifiers. We test our method on “Pasadena Urban Trees”, a new dataset of 80,000 trees with geographic and species annotations, and show that combining multiple views significantly improves both tree detection and tree species classification, rivaling human performance
Use of mobile technology-based participatory mapping approaches to geolocate health facility attendees for disease surveillance in low resource settings.
BACKGROUND: Identifying fine-scale spatial patterns of disease is essential for effective disease control and elimination programmes. In low resource areas without formal addresses, novel strategies are needed to locate residences of individuals attending health facilities in order to efficiently map disease patterns. We aimed to assess the use of Android tablet-based applications containing high resolution maps to geolocate individual residences, whilst comparing the functionality, usability and cost of three software packages designed to collect spatial information. RESULTS: Using Open Data Kit GeoODK, we designed and piloted an electronic questionnaire for rolling cross sectional surveys of health facility attendees as part of a malaria elimination campaign in two predominantly rural sites in the Rizal, Palawan, the Philippines and Kulon Progo Regency, Yogyakarta, Indonesia. The majority of health workers were able to use the tablets effectively, including locating participant households on electronic maps. For all households sampled (n = 603), health facility workers were able to retrospectively find the participant household using the Global Positioning System (GPS) coordinates and data collected by tablet computers. Median distance between actual house locations and points collected on the tablet was 116 m (IQR 42-368) in Rizal and 493 m (IQR 258-886) in Kulon Progo Regency. Accuracy varied between health facilities and decreased in less populated areas with fewer prominent landmarks. CONCLUSIONS: Results demonstrate the utility of this approach to develop real-time high-resolution maps of disease in resource-poor environments. This method provides an attractive approach for quickly obtaining spatial information on individuals presenting at health facilities in resource poor areas where formal addresses are unavailable and internet connectivity is limited. Further research is needed on how to integrate these with other health data management systems and implement in a wider operational context
Historical collaborative geocoding
The latest developments in digital have provided large data sets that can
increasingly easily be accessed and used. These data sets often contain
indirect localisation information, such as historical addresses. Historical
geocoding is the process of transforming the indirect localisation information
to direct localisation that can be placed on a map, which enables spatial
analysis and cross-referencing. Many efficient geocoders exist for current
addresses, but they do not deal with the temporal aspect and are based on a
strict hierarchy (..., city, street, house number) that is hard or impossible
to use with historical data. Indeed historical data are full of uncertainties
(temporal aspect, semantic aspect, spatial precision, confidence in historical
source, ...) that can not be resolved, as there is no way to go back in time to
check. We propose an open source, open data, extensible solution for geocoding
that is based on the building of gazetteers composed of geohistorical objects
extracted from historical topographical maps. Once the gazetteers are
available, geocoding an historical address is a matter of finding the
geohistorical object in the gazetteers that is the best match to the historical
address. The matching criteriae are customisable and include several dimensions
(fuzzy semantic, fuzzy temporal, scale, spatial precision ...). As the goal is
to facilitate historical work, we also propose web-based user interfaces that
help geocode (one address or batch mode) and display over current or historical
topographical maps, so that they can be checked and collaboratively edited. The
system is tested on Paris city for the 19-20th centuries, shows high returns
rate and is fast enough to be used interactively.Comment: WORKING PAPE
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