IEEE Geoscience and Remote Sensing Magazine - September 2016 - 43

of galaxies. Quality control will be implemented through
checking citizen performance against expert controls and
providing the same image to more than one person to
interpret. The first version of the game was launched in
October 2015 with a focus on deforestation.
THE EARTHWATCHERS PROJECT
Geodan set up the Earthwatchers project as a way to engage
students in the near-real-time detection of deforestation in
Borneo while simultaneously teaching them about remote
sensing. Embedded within a high school-level course,
students are charged with keeping watch on an area, and,
as near-real-time Landsat imagery is processed and made
available, they alert the system when changes are detected.
These changes are then investigated on the ground by nongovernmental organizations working closely with the local
communities. Such a joined-up approach has resulted in
the successful detection of illegal deforestation and real action on the ground while raising awareness among school
populations that live in areas far removed from these illicit
activities. The information collected through the Earthwatchers system also provides validation data for changedetection algorithms.
As part of the EducEO project, the Earthwatchers application is being extended to the time series of Sentinel 1 synthetic aperture radar (SAR) imagery (Figure 4) to determine
whether this data stream can be used to identify deforestation, particularly in areas that are prone to persistent cloud
cover. Part of the exercise will test the effectiveness of the different renderings of SAR data, i.e., true color, false color, and
vegetation indices or radar, in comparison with Landsat 8 imagery. We expect that the students will find patterns and issues that may never be uncovered using automated methods
alone and will provide valuable validation data. At the same
time, the students will learn to analyze SAR imagery and understand its potential as part of their mainstream education.
CHALLENGES AND BARRIERS TO ADOPTION
There are a number of key challenges associated with
crowdsourcing and CS projects that have relevance to the
use of the data for supporting EO. These challenges are
discussed in this section.
DATA QUALITY
Crowdsourced geospatial data production is typically an
open, lightly controlled process with few constraints, specifications, or quality-assurance processes. This is in contrast
to the authoritative geospatial data production practices
of national mapping and cartography agencies (NMCAs)
and businesses, which are typically less flexible and more
controlled [35]. The potential massive use of these production methods has been a concern, especially to government
organizations and academic institutions, due to differences
in the methods of production. However, EO-based mapping
projects are nearly always laboratory based and lack field
checking. Therefore, in some cases, crowdsourced data may
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ieee Geoscience and remote sensinG maGazine

FIGURE 3. Examples of different piles in the Picture Pile game corresponding to different themes.

FIGURE 4. The Earthwatchers interface showing the areas adopted

by the students and the Sentinel 1 imagery.
be the only option for ground-based calibration and validation. Moreover, experiences from the crowd could help to
inform EO data producers about product quality and fitness
for purpose, which could help to market EO products or services in the future.
ISO 19113, which is an international standard for reporting on the quality of geographic data, proposes a set
of data quality descriptors including completeness, logical
consistency, positional accuracy, temporal accuracy, and thematic accuracy [55]. It should also form a structured approach
for considering quality-assurance protocols in a crowdsourcing context. There are a number of different ways that quality
can be controlled. Where possible, automated quality-assurance methods should be used, e.g., when individuals contribute data that fall outside an allowable range. When this
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Table of Contents for the Digital Edition of IEEE Geoscience and Remote Sensing Magazine - September 2016