does not necessarily imply that the accuracy of the final prod-
uct is also high. One advantage of
ASPRS
2015 is its applicabil-
ity to data across a wide range of spatial resolutions. While
appropriate for high-resolution mapping from small
UASs
, the
standard is equally applicable to small-scale mapping from
satellites, which often have G
SD
s of several meters.
The advantage of having standards such as
ASPRS
2015 for
digital orthoimages and
DEM
s is that they provide statistically
verifiable measures of accuracy, which can be used to compare
surveys carried out using different survey methods and at differ-
ent scales. This can help the user community to develop reason-
able expectations about the levels of accuracy appropriate to
specific projects. For surveys carried out by small
UASs
there
are also a number of other benefits. The technology is compara-
tively new, and it is often difficult to know if the orthoimages
and
DEM
s produced from such surveys accurately reflect ground
conditions. By providing a comprehensive framework for test-
ing and accuracy assessment,
ASPRS
2015 will allow operators
and data users to develop an understanding of what level of ac-
curacy is appropriate and achievable under different conditions.
This will help to provide the nascent commercial
UAS
industry
with legitimacy and help to weed out unethical operators.
The surveys described in this paper are in many ways typi-
cal of the kinds of survey that are increasingly being carried
out using small
UASs
. In each case, a good number of high
quality horizontal and vertical checkpoints were available, al-
lowing project accuracy to be realistically assessed. However,
establishing large numbers of high quality checkpoints is time
consuming, and may erode many of the cost advantages of
surveying using small
UASs
. This is especially a challenge for
commercial operators, who may be under pressure to com-
plete several jobs in a single day. Under such circumstances,
rigorous accuracy checking is likely to be impractical for
every job. By using experience derived from previous jobs,
which have been checked against
ASPRS
2015, it is possible to
estimate the likely range of accuracy of the survey, and this
can later be tested in the field, if deemed necessary
.
This study shows how
ASPRS
2015 can be used to provide
estimates of accuracy for surveys conducted by small
UASs
.
By assigning accuracy classes to digital data products, it is
possible to assess whether surveying using a small
UAS
is
the most cost-effective method to obtain the required data,
or whether some alternative method, such as ground based
lidar, would be more appropriate. By allowing accuracy to be
statistically tested and compared in this manner, it is likely
that
ASPRS
2015 will make a positive contribution towards the
development of a strong
UAS
industry, which can fulfill the
expectations of users across a variety of different sectors.
Acknowledgments
The authors are grateful for support provided by the Natural
Sciences and Engineering Research Council of Canada, the
University of Calgary, and Ventus Geospatial.
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(Received 02 December 2014; accepted 20 February 2015;
final version 10 April 2015)
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October 2015
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