IEEE Geoscience and Remote Sensing Magazine - September 2019 - 48

TABLE 7. RESEARCH WORKS ON UAV-BASED TRAFFIC TARGET DETECTION AND TRACKING.
REFERENCE

PLATFORMS

AIM OF STUDY

METHODS

[175]

Rotary-wing UAV; red, green,
blue (RGB) camera

Detect and track moving objects on roads

Optical flow

[176]

UAV, gimballed vision sensor

Road-bounded vehicles search and tracking

Particle filter, point-mass filter

[177]

Rotary-wing UAV, RGB camera

Car detection and counting

SIFT + SVM

[178]

Rotary-wing UAV, RGB camera

Car detection, including the number, position,
and orientation of cars

Similarity measure

[179]

UAV, RGB camera

Vehicle detection

Multiclass classifier

[180]

Rotary-wing UAV, GoPro camera

Vehicle detection

Viola-Jones and HOG + SVM

[181]

Rotary-wing UAV, RGB cameras

Track container, moving car, and people

Optical flow

[182]

Rotary-wing UAV, infrared camera

Pedestrian detection and tracking

Classification, optical flow

[183]

Rotary-wing UAV, RGB camera

Detect, count, and localize cars

Deep CNN

[184]

Rotary-wing UAV, RGB camera

Visual object tracking (e.g., people and cars)

Deep CNN

[185]

UAV, visible camera

Vehicle detection

Deep CNN

[186]

Rotary-wing UAV, RGB camera

A large data set for object detection and tracking

Deep CNN

HOG: histogram of oriented gradient.

(a)

(b)

FIGURE 15. An illustration of vehicle detection and traffic monitor-

ing by UAVs based on deep learning: vehicle detection in (a) a
crossing and (b) a road and park. Orange boxes denote large cars
and green boxes small cars.
and leakage to help with the retrofitting of aging and energy-inefficient building stock and infrastructure.
Urban informal settlements are classified and identified based on very-high-resolution and up-to-date UAV
data to support informal settlement upgrading projects
[173]. Urban vegetation mapping is performed to identify
land cover types and vegetation coverage in urban areas,
which is significant for helping planners to take measures
for urban ecosystem optimization and climate improvement [174].
URBAN TRAFFIC MONITORING
UAVs, like eyes in the sky, provide an overhead point of
view for surveillance, especially in traffic monitoring [63],
[187], including the detection and tracking of traffic targets,
monitoring of crowds, and estimation of traffic density,
48

capacity, and flow. Traffic monitoring is beneficial for ensuring security, optimizing urban mobility, avoiding traffic
jams and congestion, and analyzing and solving environmental problems affecting urban areas.
Traffic target detection and tracking are two essential
technologies in urban traffic monitoring. However, UAVbased detection and tracking pose a daunting task, owing
to object appearance changes caused by different situations, such as occlusion, shape deformation, large pose
variation, onboard mechanical vibration, and changes in
ambient illumination [181]. Numerous methods have been
proposed for UAV-based traffic target detection and tracking, as shown in Table 7.
Various traffic targets, including cars, pedestrians, roads,
and bridges, are detected, localized, and tracked by UAV
visible or infrared cameras. An example of vehicle detection
and traffic monitoring is presented in Figure 15. In addition
to traffic scrutiny, UAV-RS can be used for traffic emergency
monitoring and documentation, pedestrian/vehicle crash
analysis, and pedestrian/vehicle behavior studies. In [188],
camera-equipped UAVs are used to record road traffic data
and measure every vehicle's position and movements from
an aerial perspective as a way to analyze naturalistic vehicle
trajectories and driving behavior.
ENGINEERING MONITORING
UAVs provide a bird's-eye view for engineers to use in the
planning, building, and maintenance of their projects [3].
With UAVs, construction managers can monitor the entire site with better visibility, so they are more informed
about project progress. In addition, engineering observation and inspection by UAVs can ensure field staff safety,
reduce production risks, and increase on-site productivity
IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE

SEPTEMBER 2019
IEEE Geoscience and Remote Sensing Magazine - September 2019

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