Navigation Satellite Systems GNSS in general and, in particular, up to now the US GPS,– inertial navigation, robotics
–unmanned aircraft and other vehicles,– image processing, computer vision, mathematical modelling, numerical analysis,
software engineering and information technologies. These technologies have responded to market needs but have also
shaped the market and created brand new mapping methods like terrestrial mobile mapping in the mid nineteen-nineties –the so-
called Mobile Mapping Systems MMS– and the unmanned aircraft-based photogrammetry already in this century –the so-
called UAV-photogrammetry and remote sensing. Other remarkable recent contributions are combined nadir-oblique
multi-head camera configurations.
In mapKITE, we leverage the latest GNSS developments the new Galileo ranging signals, the new generation MEMS-based
inertial technology, image processing techniques and lightweight multi-copter unmanned aircraft.
As for market itself, we note that since geoinformation is a modern society infrastructure that has to be guaranteed and
regulated by public bodies, a significant part of the mapping market is public. These results in public bodies subject to social
demands for quality mapping services under ever diminishing budgets. This situation is further transferred to the mapping
industry subject to complex public budget dynamics. In the mapKITE concept we add significant value without adding
much complexity by an appropriate combination of already existing MMS and UAV-photogrammetry technologies.
MapKITE responds to needs in the specific area of corridor mapping with applications in general cartography, cadastre,
civil engineering, transport and environment. More specifically it addresses the need of combining MMS surveys with [manned
or unmanned] aerial surveys and the limitations and cost of current procedures where data from different surveys, terrestrial
and aerial, are combined to produce 3D cartographic models. While terrestrial mobile mapping systems are becoming a
standard tool, their limited and insufficient view from ground is becoming apparent to users.
In 2015, the European Commission EC and the European Global navigation Satellite systems Agency GSA, in the frame
of the European Union Framework Programme for Research and Innovation “Horizon 2020,” have awarded the “mapKITE”
project to an international consortium of organizations coordinated by GeoNumerics. One of the key goals of the
project is to analyse the contribution of the European GNSS Galileo and its E1 CBOC 6,1,111 and E5 AltBOC 15,10
ranging signals to mapKITE, specially focusing on its impact in corridor mapping markets. The project spans two years, until
March 2017.
We organize the article as follows: this first section provides the motivation and background behind the new concept, section 2
provides a high-level concept description of mapKITE, section 3 goes into more details and describes the system components,
section 4 reports on the first, preliminary achievements of the ongoing development project and section 5 summarizes and
concludes.
2. THE MAPKITE CONCEPT
MapKITE targets corridor 3D mapping of roads, railways and waterways. A mapKITE system is a tandem terrestrial-aerial
mobile mapping system for simultaneous geodata acquisition and post-mission processing. The carriers of the system are a
land wheeled vehicle or a boat TV and an unmanned aircraft UA both equipped with remote sensing, navigation and
communication payloads. In mapKITE, the UA is slaved to the TV: it “follows” the TV at an approximately constant flying
height above ground figure 4, while geodata images, laser scans and other data are acquired simultaneously from the TV
and the UA. By “following” we mean that a continuous stream of waypoints is computed in the TV and transmitted –uploaded–
to the UA, to steer the latter so it “follows” the former –with some selectable and variable horizontal shift– at a given
constant altitude [of tens of meters] above ground. We refer to this steering concept as a virtual tether, from the TV to the UA.
Thus, in mapKITE, geodata acquisition happens simultaneously on ground and on air, in such a way that the unmanned aircraft
imaging sensors “see” the terrestrial vehicle continuously.
Our tandem mapping concept can be seen in two different ways: from a mapping unmanned aerial system UAS point of view, it
is an UAS whose ground control station GCS moves. From a terrestrial mobile mapping TMM point of view it is a TMM
system –on a terrestrial vehicle TV– complemented with a mapping UAS.
Indeed, in mapKITE, the GCS of the unmanned aircraft is in the terrestrial vehicle. Since the GCS and the UA operate so close
from each other, the GCS-to-UA limited distance within human visual range imposed by unmanned aircraft regulations do not
affect mapKITE and, therefore, there is no restriction on the length ad spatial scope of the missions other than vehicle energy
supply autonomy. In practice, there is no restriction as the UA batteries can be replaced as needed. Note also that landing and
take-off manoeuvres for battery replacement can be turned into calibration manoeuvres of the remote sensing instruments.
A key characteristic of mapKITE is its geodetic positioning and orientation concept: the TV carries a surveying-grade
navigation real-time and orientation post-processing system as it belongs to its MMS nature; and the UA carries a surveying-
grade GNSS receiver or, additionally, a lightweight tactical- grade inertial measurement unit. Furthermore, the TV carries a
geometric target of known size and shape on its roof figure 3 and, possibly, a number of radiometric calibration targets. The
TV optical target materializes the accurate trajectory delivered by the MMS orientation system as a continuous series of
kinematic ground control points KGCPs to be observed by the UA remote sensing instruments. In mapKITE, KGCPs are, in a
way, for free, as all what we have to do to get them is to install a target on a vans roof and measure a couple of lever arms.
Clearly, the strength of KGCPs is that they are accurate, many and cheap. Their weakness is that they can only be “seen” in
one image. We compensate for this weakness by measuring their scale section 3. Another advantage of KGCPs is that they can
easily become traditional, static GCPs in the obvious way. Mathematical models to introduce scale factor measurements
can be found in Molina et al., 2016.
By combining accurate aerial control position or position-and- attitude, accurate continuous ground control KGCPs and
accurate sparse static ground control GCPs we set up a remarkably strong control configuration for later sensor
orientation and calibration with integrated sensor orientation ISO methods or for just sensor orientation with the “Fast AT”
method Blázquez and Colomina, 2012a.
This contribution has been peer-reviewed. doi:10.5194isprsarchives-XLI-B1-957-2016
958
We note that the velocity information provided by the aircraft INSGNSS system can be used for time synchronization of the
aircraft cameras Blázquez and Colomina, 2012b. This is of particular interest for mapKITE and for any aerial remote
sensing system equipped with low-cost mass-market devices.
Thus, measurements made on geodata acquired under the mapKITE paradigm, will be post-processed under a new,
extended ISO orientation-calibration concept to deliver accurate oriented-calibrated images of corridors and their environment
with ground sampling distances ranging from 2 to 10 cm.
Last, we call the attention of the reader to the importance of navigation in the practical execution of mapKITE. Navigation
is a real-time position, or position-velocity or position-velocity- attitude determination. The unmanned aircraft has to follow a
path which is a translation of the terrestrial vehicle path which, in turn, is computed by the navigation system of the terrestrial
vehicle. The path has to be moderately accurate few meters and smooth free of spurious acceleration and jerk peaks for
obvious safety reasons. Safe navigation of the mapKITE unmanned aircraft is not the central topic of this article but is a
critical part of of mapKITE which is addressed in the H2020 project and that relies on current and future GNSS infrastructure
and ranging signals and on optical tracking of the TV roofs target by an independent, redundant image-based navigation
system.
3. THE MAPKITE COMPONENTS
