
2 Wenhui Chen 1et al.
1 Introduction
Aircraft flight phases include departure, cruising, and landing. Compared to other phases, the landing phase has
the largest risk of flight accidents, as it is the most difficult phase to operate in. A successful landing requires
maintaining the proper glide angle and descent speed, as well as ensuring that the aircraft’s flight path is aligned
with the runway centerline and crosses the intended landing point on the runway. Therefore, reducing pilot work-
load and improving safety during the landing phase are vital goals for the aviation industry. Existing landing
phase navigation systems include the instrument landing system and ground-based augmentation system. How-
ever, the deployment cost of such systems is high. In recent years, the visual navigation system has emerged as
a new development in this field due to its low cost. Many studies [1–6] are aimed at achieving automatic land-
ing with the help of computer version technology. As an important part of the visual navigation system, airport
runway segmentation classifies the runway markings at the pixel level, resulting in segmentation results that can
indicate whether the aircraft is aligned with the runway centerline and whether the current glide angle is reason-
able, which helps pilots better perceive the runway position, enabling automatic landing and improving safety
during the landing phase.
Existing solutions to airport runway segmentation are mainly implemented by identifying runway character-
istics such as textures [7] and line segments [8, 9]. However, such traditional image processing methods provide
limited categories and cannot distinguish instances in the same category. Moreover, these methods are difficult
to adapt to complex scenes, as some unrelated objects with similar shapes or structures may decrease accuracy.
Segmentation methods [10–13] based on deep learning (DL) provide good generalization and performance but
rely on related datasets. A few studies [14–17] have proposed datasets for airport runway segmentation. However,
the datasets in [14–16] are remote sensing image datasets taken from the Earth view, which are not applicable to
aircraft landing phase scenes. Additionally, they all have a small quantity of data and are not publicly available.
Due to the lack of relevant large-scale, publicly available datasets, existing segmentation methods based on DL
are difficult to apply to this field. In addition, those methods cannot be perfectly applicable because they mainly
target irregular objects, whereas airport runway segmentation is for objects with more regular shapes.
To address the two issues raised above, namely, the lack of large-scale, publicly available datasets and the in-
applicability of existing methods, we propose a benchmark for airport runway segmentation (BARS), along with
a smoothing postprocessing module (SPM) and a contour point constraint loss (CPCL) function. Furthermore,
the average smoothness (AS) is designed to measure the smoothness of the segmentation results. BARS contains
10,256 airport runway images from the aircraft view, with images captured from the X-Plane simulation platform
1. There are 30,201 instances with three categories in BARS. The LabelMe toolbox 2is used to complete the
annotation, and a semiautomatic annotation pipeline is designed to reduce the annotation workload. Compared
with other datasets [14–17], the proposed BARS 1) has the largest number of images, 2) contains the fullest
categories and instance annotations, 3) involves a variety of scenes, and 4) holds large variations as the images
are obtained in different weather and at different times. Some examples from BARS and other datasets are shown
in Fig. 1. We employ instance segmentation methods to simultaneously segment different runway markings and
to distinguish instances, such as multiple runways within an image. Eleven representative instance segmentation
methods, which include mask-based [18–20] and contour-based methods [21,22], are evaluated on BARS. SPM
and CPCL are proposed based on the regular shape airport runway characteristic. SPM is a plug-and-play mod-
ule that is designed for the inference phase of mask-based instance segmentation methods. SPM employs coarse
to fine smoothing operations to alleviate the problem of rough segmentation boundaries. CPCL is proposed for
contour-based methods, which can smooth boundaries and speed up the convergence of the model by introducing
prior knowledge to restrict the contour points.
1X-Plane, https://www.x-plane.com/
2Labelme, http://labelme.csail.mit.edu/Release3.0/