
MM ’22, October 10–14, 2022, Lisboa, Portugal Yue He et al.
Figure 1: Samples of complex scenarios in the CULane dataset:
(a) Crowded (b) Dazzle (c) Shadow (d) Night. The �rst column
shows the ground truth, and we highlight the elliptical re-
gion for comparison between lines before repainting (second
column) and after repainting (third column).
Either combining shape prior of lanes or designing the auxiliary
task has shown its comprehensive consideration and competitive
results for lane detection, it is still a challenging task due to many
factors such as the wide variety of lane markings appearance includ-
ing solid or dashed, white or yellow. Moreover, complex road and
light conditions leading to occlusion and low illumination increase
the invisibility of lanes. All these diculties require the method to
have the ability to extract lanes under complicated environments.
Taking CULane dataset [
23
] as an example in Fig. 1, we present
four representative scenarios, including crowded, dazzle, shadow,
and night. In these scenarios, complete lanes cannot be visually
detected by comparing lanes in the wild (the second column) with
the ground truth annotations (the rst column). The inherent in-
visibility of lanes hinders the progress of the algorithms. In this
paper, we focus on nding a more discriminative lane feature space
and maintaining a similar distribution of lanes in the wild. The
Repainting and Imitating Learning (RIL) framework is proposed to
increase the visibility of lanes by repainting module without extra
data or labor labeling, and improve feature discrimination while
transferring lane knowledge from teacher to student via imitating
learning simultaneously.
First and foremost, the inherent invisibility of lanes in the wild
intractable by current lane detection methods is alleviated by a sim-
ple but eective repainting module in our repainting step. Through
this module, virtual data is generated based on the location of lanes
annotated in the ground truth without the requirement of extra data
or laborious labeling. This module highlights the fuzzy lanes and
makes lines more prominent and continuous. As shown in Fig. 1,
the lane regions in the third column become more distinctive and
continuous while maintaining other non-lane regions unchanged.
Based on these ideal lanes, the teacher will be trained in advanced
and achieves upper bound performance.
A simple solution by directly adding the virtual data as data
augmentation does not work, since there exists a distribution gap
between virtual data and real data. Thus, to better utilize virtual data,
imitating learning step is introduced including a scale-fusing distil-
lation module and a coupled adversarial module. In the scale-fusing
distillation module, dierent stages of feature representations from
the teacher are treated as the ideal enhanced feature space. Noticing
that the teacher model has the same architecture as the student.
The teacher’s feature maps of the same size as the student’s feature
maps are distilled directly. Besides, the teacher’s larger feature maps
are down-sampled to distill student’s semantic feature maps simul-
taneously for ner lane details. Both the same scale and cross scale
information are distilled, helping student to imitate the teacher.
To further eliminate distribution gaps not only between dierent
networks but also between dierent input data, coupled adversarial
module is proposed to build a bridge to connect networks as well
as data. A pair of discriminators are coupled by adding in another
student’s output of virtual data. The rst net-sensitive discrimina-
tor is to distinguish teacher and student networks when they are
fed into virtual data. The second data-sensitive discriminator is to
distinguish between virtual data and real data which feed to the
student network. By coupling two discriminators, the student can
better imitate the enhanced teacher features dynamically through
the learning process.
Our main contributions are summarized as follows:
•
We introduce a simple yet eective Repainting and Imitating
framework (RIL) for lane detection, focusing on discriminat-
ing lane features and maintaining the similar distribution of
lanes in the wild by nding an enhanced feature space.
•
We repaint the real lane data to ideal virtual data in the
repainting step, achieving enhanced representation under
complicated environments.
•
We combine the scale-fusing distillation module with the
coupled adversarial module in the imitating step, building the
bridge between networks and data to weaken the learning
gap.
The proposed RIL framework can be easily plug-and-play in most
cutting-edge methods without any extra inference cost. Experi-
mental results prove the eectiveness of RIL framework both on
CULane [
23
] and TuSimple [
33
] for four modern lane detection
methods including UFAST [
26
], ERFNet [
27
], ESA [
11
] and Cond-
LaneNet [14] respectively.
2 RELATED WORK
Lane detection Recent approaches [
4
,
16
,
19
,
25
] focus on the deep
neural networks and signicantly boost the lane detection perfor-
mance due to the powerful representation learning ability. Some
methods[
11
,
23
,
27
] treat lane detection as a semantic segmentation
task. For instance, SCNN [
23
] designs slice-by-slice convolutions
within feature maps to exchange pixel information between pixels
across rows and columns in a layer. Inspired by network architec-
ture search (NAS), CurveLanes-NAS [
36
] designs a lane-sensitive
architecture to incorporate both long-ranged coherent lane infor-
mation and short-ranged local lane information. Despite the promis-
ing results, the computational complexity in these methods brings
heavy inference overhead. Therefore, row-wise classication based
methods [
9
,
14
,
26
,
37
] have been proposed for ecient lane detec-
tion. These approaches divide the input image into grids and predict
the most probable cell to contain a part of a lane, which realize the
trade-obetween speed and accuracy. More recently, SGNet [
28
]
introduces a structure-guided framework to accurately classify, lo-
cate and restore the shape of unlimited lanes. Unlike the systematic