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Traffic Sign Recognition System (TSRS): SVM and Convolutional Neural Network

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TSRS (Traffic Sign Recognition System) may play a significant role in the self-driving car, artificial driver assistance, traffic surveillance as well as traffic safety. Traffic sign recognition is necessary to overcome the traffic-related difficulties. The traffic sign recognition system consists of two parts—localization and recognition. In the localization part, traffic sign region is located and identified by creating a rectangular area. After that, in recognition part, the rectangular box provided the result for which traffic sign is located in that particular region. In this paper, we describe an approach toward the traffic signs recognition system. Here, we worked on 12 selected signs for traffic sign detection and recognition purpose. In this intention, we used a support vector machine (SVM) and convolutional neural network (CNN) individually to detect and recognize the traffic signs. We obtained 98.33% accuracy for SVM with an 80:20 train and test data ratio. On the other hand, the test result was 96.40% accurate for CNN.
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Traffic Sign Recognition System (TSRS): SVM and
Convolutional Neural Network
Nazmul Hasan1, Tanvir Anzum1, and *Nusrat Jahan2
1Computer Science and Engineering Department
Daffodil International University
{nazmul15-7914, tanvir15-7890}@diu.edu.bd
2Senior Lecturer
Computer Science and Engineering Department
Daffodil International University
nusratjahan.cse@diu.edu.bd
Abstract. TSRS (Traffic Sign Recognition System) may plays a significant
role in self driving car, artificial driver assistances, traffic surveillance as
well as traffic safety. Traffic sign recognition is necessary to overcome the
traffic related difficulties. The traffic sign recognition system has two parts-
localization and recognition. In localization part, where traffic sign region is
located and identified by creating a rectangular area. After that, in
recognition part the rectangular box provided the result for which traffic
sign is located in that particular region. In this paper, we describe an
approach towards traffic signs recognition system. Here, we worked on 12
selected sign to traffic sign detection and recognition purpose. In this
intention, we used Support Vector Machine (SVM) and Convolutional
Neural Metwork (CNN) individually to detect and recignize the traffic
signs. We obtained 98.33% accuracy for SVM with 80:20 train and test data
ratio. On the other hand, the test result was 96.40% accurate for CNN.
Keywords: Image processing. SVM. CNN. traffic sign.
1 Introduction
With the rapid growth of technological development, vehicles have become an
essential portion of in our routine lives. Because driving vehicles without follow
traffic rules, it creates more and more intricate traffic on the road. As a result, it is
one of the major reasons behind accidents every year. In recent times road
accidents are happening regularly in increasing manner across the world. Leading
reason of most road accidents is the ignorance or unawareness of the traffic sign.
The meaning of traffic sign is any entity, device, or board on the road that entity
carries the rules, indicates the warning or provides other explanation regarding
driving. Therefore, it also provides necessary information through traffic signals
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and traffic control devices to continue smooth car driving.
Traffic sign detection and recognition system is an crucial issue to reduce taffic
and increase the sustainability of selfdriving car without any incidence. TSRS
plays a crucial role in autonomous vehicle, smart driving and smart traffic system.
The traffic sign is used in Bangladesh since 1930’s and those are inadequate in
this current traffic situations. So, we need to underpin TSRS to provide an
autonomous vehicle to reduce traffic as well as road accident.
An approach assemble with video camera and an active machine with the
vehicle is a simple driver assistance system focused on frame by frame
observation of the motion frames can be implemented and there by generated the
alert signals accordingly. So, the driver would be able to take the decision
effortlessly. Road sign analysis is one of the significant aspects for automatic
driving support system. Real time qualitative road sign observation is the root for
any updated transport system. In this paper, we proposed this system to recognize
traffic sign with supervised classification algorithms. The outcome of this study
can be used for recognizing traffic signs and direction also to slow down or direct
driver to another safe route.
Fig. 1. Basic block diagram for TSRS
A simple block diagram to present the overall prospective has depicted in
figure 1. With the help of this diagram, we demonstrated the proposed system
towards automated car. In our proposed approach images is captures from vehicle
using a video camera. After pre-processing input data classification algorithm was
established to detect and recognize the traffic signs. Finally, we introduce a driver
alert system to minimize the error of car driving approach.
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2 Related Work
This section for highlights some recent related research works. Autonomas car is a
recent research topic. We found many researches on this field and the working
progress is too high.
In 2019, Wei-Jong Yang et al. proposed an approach to recognize traffic sign.
They worked with shaped based detection algorithms and for classification
purpose they choose convolutional neural network. After simulation they got 97%
sign recognition accuracy [1]. In this paper [2] author proposed SVM based
classification algorithm to recognize traffic sign. Here, they considered 8 types of
road signs. For training purpose they used 600 different images for each signs and
for test purpose 120 images was considered. In this paper, they tested individual
signs with real data and their accuracy level was 66.6% to 100%. Prashengit Dhar
et al. in 2017 proposed a Traffic Sign Recognition (TSR) system. Here, they were
used HSV color model and deep CNN for automatic features extraction as a
classifier. After this study, they achieved 97% accuracy [3]. In 2019 [4] Aashrith
and et al. used Convolutional Neural Networks for recognizing traffic sign. Here,
they found 99.18% accuracy on using Belgium Data and German Traffic Sign
Benchmark (GTSDB). Where as they got 99.50% accuracy almost 0.32%
improvement at accuracy. In 2016 at paper [5], Di Zang et al. classified their
dataset using Support Vector Machine then detection part is done by CNN. Their
accuracy was almost 96.50%, and they used GTSDB dataset. In 2017 at paper [6],
Ardianto et al. used SVM to classified object and got 91.5% accuracy in detection
purpose and they also used GTSDB dataset. They improved it to add a feature
called Histogram of Oriented Gradients (HOG) that help to increase its accuracy
up to 98%. In 2017 Shi et al., applied SVM to detect which region of image
contain a traffic sign [7].
Pavly Salah Zaki and et al. worked on traffic sign detection, multiple entity
detection system. In 2019, they used Faster Recurrent CNNs, Single Shot Multi
Box Detector along with several feature extractors to detect traffic sign. However,
they underpin F-RCNN to get best results. Here, they used the GTSDB dataset.
The GTSDB holds complete 900 images, where 800 for training and 100 for
testing [8]. In 2020, Yanmei Jin and et al. also worked with GTSRB dataset to
propose a Single Shot Detector algorithm combine with multi feature fusion and
they called it MF-SSD. However, in this time they divided total 900 images into
600 training and 300 as a test data to detect traffic sign [9]. In 2017, Yassmina
Saadna and Ali Behloul discussed a system to identify and recognize traffic sign.
Their main goal was to find out traffic sign detection methods to locate the
regions-of-interest that contain traffic sign. They divided the methods into 3 steps-
focused color, shape, and finally considered learning based methods [10]. In 2016,
for detecting and classifying the traffic signs they proposed an approach. It has 2
main steps: road sign detection, after that classification with recognition. To
classify the traffic sign they used neural network and to complete this work they
picked four types of traffic signs: Stop, No Entry, Give Way, and Speed Limit
Sign. Considered total 3 hundreds sets images, and they got 90% and 88%
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accuracy for detection and recognition purpose [11]. So, detection and recognition
of traffic sign is necessary to build an autonomas car driving system.
3 Proposed Methodology
To recognition traffic sign we focused two machine learning algorithms. Many
recent research works on traffic sign used SVM and CNN. For detecting and
recognizing traffic sign we used these two algorithms. In the next step we also
evaluated the proposed approach with CNN and SVM.
3.1 Data Collection and Preparation
To complete this study a dataset was built from cropping video frame. We also
collect some random video and crop traffic sign area to build a real dataset. Then,
we categorized its own classes and split the whole data into training and validation
dataset. We have total 1200 images to propose SVM and CNN model.
Table 1. 12 Traffic Signs with Description.
Description
Traffic Sign
Description
Traffic Sign
Turn Left
Danger
Stop
40km/h
Only Left
30km/h
Only Right
Turn Right
Road Merges
Ahead
Pedestrian
Speed Breaker
Bike
5
We have considered 12 different classes and each class completed with 100
images. Split the whole dataset as training and validation purpose. To generate a
model with SVM, 80% data for trining and 20% data for testing purpose is
considered. Meanwhile, for CNN classification we have divided dataset into two
classes train and validation. For training purpose data volume was 1080 images
and 120 images for testing purpose, where total 12 different traffic signs was
contained. Table 1 to represnt the selected 12 traffic signs. Here, we illstrated evey
traffic sign with sample an image.
In the next section, we are attending to elaborate the work procedure of our
proposed approach to detect and recognize traffic sign.
3.2 Convolutional Neural Network
Convolutional neural network is a part of deep learning approch. Convolutional
neural network represents a vast breakthrough in image recognition. Many
research fields focused on CNN to achieve the highest accurate result. A CNN
model constracts with following four layers:
Convolutional layers
Relu function
Polling layers
Fully connected layer
Convolution is the first step to create complete network. Here, Convolutioal
operates on two images in 2D format. One as a input image, and another output
image. It helps to understand the features from images by making relation between
pixels. A convolution of two funcation f and g is defined with following the
equation
𝑚
(𝑓 𝑔)(𝑖) = ∑ 𝑔(𝑗) 𝑓(𝑖 𝑗 +m/2) (1)
𝑗=𝑖
Next, relu is placed after convolution operation. This “relu” fuction considered
for executing non-linear operation. It performs on pixel wise operation and sets 0
insted of all negative values. There are other non-linear functions such as tanh or
sigmoid also used in CNN but “relu” performs best amon them in different
situations. On the other hand, Polling progressively decrese the size of the input
images. Polling helps to decrese the number of dimentions and the number of
claculation required. Polling also helps to control overfitting. There are many
types of polling. But in this paper we used max polling.
Fully connected layer, combines our features into output stage. It predicts the
class level with better accuracy. The error is computed and then occured back
propagation. This process is continue layer by layer. A sample flowchart for our
proposed model on CNN and SVM is given in figure 2.
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Fig. 2. Flowchart of our model
3.3 Support Vector Machine (SVM)
SVM is a familiar supervised machine learning algorithm. It is usually worked for
regression and classification problems. This algorithm distinct classess by
generating hyperlane between two classes. Actually it divides dataset into required
classes. In the SVM model, it will be clearly understanding with an example for
two classes. We can easily understand the process of SVM model with the help of
figure 3.
Fig. 3. Spilt data into two classes (SVM)
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To understand the work process of SVM we neeed to know the region-of-
interest “ROI module. This region of interest follow three steps. First one is,
color transformation. That converts the colourful images into grayscale images.
The second step is to control shape of images. Finally, it refines the ROI. This
exploits the regularity of traffic signs with their color and shape with better
competence.
In this paper, to describe the methodology, the size of the cells and blocks are
varied to get several image sizes. We used 9-bin histograms for this methodology.
To train the model we rescale the training images to 32x32 pixel images. HOG
descriptors to calculate and train SVM classifier. The m number of support vectors
are merged to a single one where multiply every vector with its weight “a” and
adding it with a global vector “v”. Equation 2 for cumputing the suport vector
[12].
m
𝑣 = ∑ 𝛼𝑖. 𝑣𝑖 (2)
𝑖
Now, we are going to illustrate the whole work process of SVM with the help of
figure 4. Here, we depict all the steps of SVM to reciognize the traffic signs for
TSRS.
Fig. 4. SVM for Traffic Sign Detection and Recognition
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4 Result Analysis
In this section we are going to discuss about result which was obtained from SVM
and CNN. SVM classification for Traffic sign detection and recognition provided
98.33% accuracy (80:20 data split ration), while in CNN method we achieved
99.56% training accuracy and 96.40% validation accuracy. The training accracy,
validation accuracy and loss of CNN model is visualized in figure 5 and 6.
Fig. 5. Accuracy of Training and validation
Fig. 6. Line chart for Training and validation loss
For SVM method we were getting 98.33% accuracy when we splited total
dataset into 80:20 ration for training and testing purpose. However, we acieved
99.17% accuracy when considered 90:10 ration. Figure 7 for presenting the
performance of SVM.
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Fig. 7. Result of SVM
After that, we developed a system using SVM to evaluate the results with real
time video. The detection part uses image processing techniques that creates
contour on each frame and finds all ellipse or circles among those contours. Then,
the detection part marked as categorized traffic sign. Some sample results shown
in following figures.
Fig. 8. Recognize Danger Sign
Fig. 9. Recognize Drive 30 km/h” Sign
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Fig. 10. Recognize Turn Right” Sign
Figure 8, 9, and 10 to understand the performance of SVM with the help of some real
time data. If we implement the full system with CNN then it will be work well then SVM
as we have mentioned their accuracy level. After complete our study we obtained TSRS can
be an established and sustainable system. Many researches are going on with traffic issues
and self-car driving purpose. We needed an accurate model to implement this system to
provide the better solution in every case.
5 Conclusion
This paper study was to represent an original effective traffic sign detection and
recognition approach towards the design of TSRS. As a recent research topic
TSRS is getting popular day by day. In this study, it is done using SVM and
CNN classification algorithms to decline extensive traffic difficulties. In our ex-
periment, we obtained highest training accuracy from CNN 99.56%, while the
test accuracy was 96.40%. We showed the real time evaluation results of SVM,
where the system performed 98.33% accurately. Many research focused on SVM
and CNN to solve this specific problem.
In future, our aim is to increase the number of traffic sign classes with large
amount of quality data. As in a machine learning research, to maintain data vol-
ume and data quality is most important and time consuming part. To provide a
complete system to overcome the traffic issues our ambition is to implement a
system with distance calculation form car to traffic sign.
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