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Learn how Data Science powers Automatic Traffic Challan

Published: 25th April, 2023
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Harshini Bhat

Data Science Consultant at almaBetter

Explore how data science enables automatic traffic challans. Discover the role of machine learning and computer vision in improving road safety.

Imagine driving down a busy street, lost in thought when suddenly you hear the sound of a siren behind you. Your heart rate increases, wondering what traffic violation you have done. As you wait for the officer to approach your car, you wonder how they even know I broke the law.

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The answer lies in the power of data science. Traffic challans, or tickets, are no longer issued by police officers on the road. Instead, a complex system of cameras, sensors, and algorithms work together to automatically detect traffic violations and issue challans to the offending driver.

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In this article, we will explore how data science power this innovative system, making our roads much safer and reducing human error by detecting and penalizing traffic violators efficiently. At the very outset, first, let us know what the Automatic Traffic challan system is. The Automatic Traffic Challan System is a computerized system that aims to make the process of issuing traffic tickets for traffic violations more efficient. It uses cameras, sensors, and algorithms to detect and identify traffic violations like running a red light or over-speeding.

As we have understood the basics of the automatic traffic challan system. Now let us learn to create an Automatic Number Plate Recognition system. We will be following the steps as shown below

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Step 1: Research

A good data scientist spends ample time researching the problem statement to make the solution holistic and comprehensive. We may first have to answer some basic questions, like how a real-time solution is required. How much accuracy is required? Let us try answering a few of these questions to get a better understanding.

Who are the stakeholders?

There are multiple stakeholders involved in this system. Traffic police are the primary users of the system, as they are responsible for issuing traffic tickets based on the violations detected by the system. Vehicle owners are the ones who are penalized if they are found to have violated any traffic rules. The municipal corporation plays a crucial role in setting up the system, as they are responsible for maintaining the city's infrastructure, including the roads, signals, and cameras. Finally, the government enacts laws related to traffic and provides the necessary funds for setting up and maintaining the system.

How can data be collected and what are the Factors affecting the quality of the data?

Data collection for an automatic number plate recognition (ANPR) system typically involves capturing images or video footage of vehicles and their number plates using cameras mounted on roads, toll booths, parking lots, or other locations. The ANPR system can then process and analyze the data to automatically read and recognize the number plates.

Factors affecting the quality of the data collected for an ANPR system include :

  1. Camera placement and angle: The positioning and orientation of the camera can affect the quality and clarity of the image captured.
  2. Lighting conditions: Poor lighting, excessive glare or reflections from the sun, and headlights can affect the quality of the image captured, making it difficult for the ANPR system to recognize the number plate.
  3. Weather conditions: Adverse weather conditions such as rain, snow, fog, or haze can affect the visibility and clarity of the number plate, making it difficult for the ANPR system to recognize it.
  4. Vehicle speed: The vehicle's speed can affect the image's quality captured, especially if the vehicle is moving at high speed.

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What is the accuracy required with respect to real-time solutions?

Real-time processing means that the ANPR system can process the data as it is captured, without any significant delay or lag, and provide quick and accurate results. A high-accuracy ANPR system should recognize number plates accurately, even when partially obscured, damaged, or distorted. To develop a model, we can first try and experiment with a single class of detecting number plates of cars and then improve the model by customizing it to our requirements.

Step 2: Design the Solution

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Experimentation - Identify the Vehicle: ANPR

Baseline Model

Establishing a baseline model is essential to develop an effective automatic number plate recognition (ANPR) system. Creating such a model requires careful consideration of various factors, including developing a Proof of Concept (POC), dataset selection, pre-trained models, and algorithm selection.

The first step in creating a baseline model for an ANPR system is to develop a Proof of Concept. This involves building a simple prototype or test model to demonstrate the key features and functionality of the system. The POC can help test the feasibility of the ANPR system and establish a baseline for its performance.

The next step is to select a dataset of vehicle images with their associated number plates. A publicly available dataset can ensure that the system is developed on a diverse and representative data set. This will also help in comparing the performance of the ANPR system with other ANPR systems. A large dataset can help the system to learn different plate sizes, font styles, colors, and other attributes that can affect the recognition accuracy.

Pre-trained machine learning models, such as convolutional neural networks (CNNs), can be used as a starting point for developing an ANPR system. These models help reduce the amount of training required for the ANPR system and provide a good starting point for the system's architecture. CNNs have shown remarkable performance in the field of object detection, and their use in ANPR is becoming more and more common.

Custom Training & Model Tuning

Custom training and model tuning are key aspects of machine learning that involve refining an existing model or building a new one to improve its performance. Building an Automatic Number Plate Recognition (ANPR) system involves a few important steps.

Data collection and training: we need to collect data that includes high-quality images of number plates from various sources, such as cars, buses, and trucks. This data is then used to train the ANPR model, teaching it to recognize different features in number plates.

Eliminate possible corner cases: It's important to test the model on various datasets to ensure it can handle different scenarios, such as varying lighting or weather conditions. This step helps to identify any possible "corner cases" where the model may struggle to recognize number plates. Once these cases are identified, the model can be retrained to handle them better.

Evaluate the trade-off between speed and accuracy: when building an ANPR system, we must evaluate the trade-off between speed and accuracy. The system needs to be fast enough to process many vehicles quickly while maintaining high accuracy. To evaluate this trade-off, we can compare the performance of different models on the same dataset using metrics such as precision, recall, F1 score, and inference time. Based on the results, the most suitable model can be deployed.

Ground Testing, Monitoring, and Re-training

Ground testing, monitoring, and re-training are all important steps in implementing a Machine Learning solution that works effectively in the real world. This process involves a few key steps in an Automatic Number Plate Recognition (ANPR) system.

  • We need to test the solution in a real-world environment, replicating all possible scenarios where the system may be required to recognize number plates. This includes varying lighting conditions, distances, angles, weather conditions, and different types of number plates. This testing helps to identify any weaknesses in the system and provides feedback for improvement.
  • Monitoring the system's performance is also crucial to ensure that it remains accurate and effective over time. This involves regularly evaluating the system's accuracy under different conditions, so you can detect any issues that arise and address them promptly.
  • If the system's performance decreases or new number plate types are introduced that it cannot recognize, re-training the system is necessary. This involves collecting new data and training the system on that data to improve its accuracy and effectiveness. These steps, ensure that our ANPR system remains effective and accurate over time.

Now that we have got a thorough understanding of the use case, we can now go ahead with the implementation

To check out step 4 and step 5, which is the baseline model implementation, you can follow this Google Collab notebook.

Conclusion

To wrap things up, we can see that the Automatic Traffic Challan System is a remarkable example of what data science can achieve. It leverages cameras, sensors, and smart algorithms to accurately and efficiently detect traffic violations, taking human error out of the equation. Creating an Automatic Number Plate Recognition system is a vital part of this process, but it requires a thoughtful approach that takes various factors into account, like selecting the right dataset, using pre-trained models, choosing the right algorithm, and fine-tuning the model. By doing so, we can develop an ANPR system that delivers real-time and accurate results, improving road safety and holding traffic violators accountable for their actions.

INTERVIEW QUESTIONS

  1. Can you explain the principles behind convolutional neural networks (CNNs) and how they can be applied to license plate recognition?

Answer: Convolutional Neural Networks (CNNs) are a type of neural network that is good for recognizing images. CNNs work by learning to extract features from images, using a set of layers that perform operations such as filtering, pooling, and activation. In the case of ANPR, CNNs are used to recognize license plates from images captured by cameras. The CNN model is trained on a dataset of license plate images, where the input is the image, and the output is the license plate number. During training, the CNN learns to extract and classify the features of the license plate, such as the characters' shape, size, and color, as well as any patterns or textures on the plate.

The basic idea behind CNNs is that they use a set of learned filters to perform convolution operations on the input image. The convolution operation involves sliding the filter over the image and computing the dot product between the filter weights and the corresponding pixel values in the input. The resulting feature maps are then passed through a non-linear activation function to introduce non-linearity into the model.

The CNN architecture typically consists of several layers, including convolutional, pooling, and fully connected layers. Convolutional layers extract features from the input image while pooling layers reduce the spatial dimensions of the feature maps.

Finally, fully connected layers process the flattened feature maps and produce the final output. In ANPR, CNNs can achieve high accuracy and robustness in recognizing license plates, even in challenging conditions such as low light, poor image quality, or occlusion. However, one of the challenges of using CNNs for ANPR is obtaining a large and diverse dataset of license plate images that covers various license plate types, styles, and variations.  

How would you evaluate the performance of an ANPR system?

Answer: The performance of an ANPR (Automatic Number Plate Recognition) system can be evaluated using various metrics such as:

  1. Accuracy: This measures the percentage of correct license plate recognition among all the license plates detected by the system.
  2. Precision: This measures the percentage of correct license plate recognitions out of all the license plate recognitions made by the system.
  3. Recall: This measures the percentage of correct license plate recognitions out of all the actual license plates present in the scene.
  4. Processing Speed: This measures the time taken by the system to detect and recognize license plates.
  5. Robustness: This measures the system's ability to perform well in different lighting conditions, weather conditions, and varying camera angles.

A good ANPR system should have high accuracy, precision, recall, fast processing speed, and high robustness to perform well in real-world scenarios.  

QUIZ

Q1. What is the advantage of using a CCNN in ANPR system?

  1. Improved accuracy in character recognition
  2. Faster processing of images
  3. Better detection of license plates
  4. None of the above

Answer: A) Improved accuracy in character recognition

Q2. Which layer of CNN is responsible for detecting features such as edges and corners in an image?

a) Convolutional layer

b) Pooling layer

c) Fully connected layer

d) None of the above

Answer: a) Convolutional layer

Q3. What is the role of a fully connected layer in CNN for the ANPR system?

a) To reduce the dimensionality of the feature map

b) To perform the final classification of the characters

c) To generate the output image

d) None of the above

Answer: b) To perform the final classification of the characters

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Read our blog on the receptive field for CNN in layperson's words to know more about convolution neural networks.

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