Introduction
Counting people in a given area is an
important task in many fields, such as security, retail, and transportation.
However, manually counting people is a tedious and time-consuming task.
Therefore, developing an automated system for counting people can greatly
benefit these industries. In this article, we will explore how to build a human
detector and counter using Python with the help of data science.
Human
Detection
The first step in building a human counter
is to detect the presence of humans in an image or video stream. This can be
achieved using object detection techniques. One popular object detection
technique is the use of convolutional neural networks (CNNs). CNNs are deep
learning models that have proven to be effective in object detection tasks.
There
are several pre-trained CNN models that can be used for human detection, such
as YOLO (You Only Look Once), Faster R-CNN (Region-based Convolutional Neural
Networks), and SSD (Single Shot Detection). These models can detect humans in
real-time with high accuracy.
Once
the human detection model is selected, we need to implement it using Python.
The Python programming language has several libraries that can be used for
object detection, such as OpenCV, TensorFlow, and PyTorch. In this article, we
will use the TensorFlow Object Detection API, which is a powerful and
easy-to-use framework for building object detection models.
To
use the TensorFlow Object Detection API, we need to first install the required
dependencies, including TensorFlow, protobuf, and pillow. Once the dependencies
are installed, we can download the pre-trained model and the configuration
files from the TensorFlow Object Detection Model Zoo.
The next step is to write a Python script
that uses the pre-trained model to detect humans in an image or video stream.
The script should load the pre-trained model and the configuration files, and
then use them to perform object detection on the input image or video frames.
The output of the object detection model should be a list of bounding boxes that
contain the detected humans.
Human
Counting
Once we have detected humans in an image or
video stream, the next step is to count them. There are several ways to count
humans, but one of the simplest and most effective methods is to use centroid
tracking.
Centroid
tracking is a technique that tracks objects by their centroids. The centroid is
the center of mass of an object, which can be calculated by taking the average
of its x and y coordinates. To use centroid tracking, we need to first extract
the bounding boxes that contain the detected humans from the output of the
object detection model.
We
can then calculate the centroid of each bounding box, and use these centroids
to track the movement of each human. For each frame of the video stream, we can
compare the centroids of the detected humans with the centroids of the
previously detected humans. If the distance between a current centroid and a
previous centroid is below a certain threshold, we can assume that the current
centroid corresponds to the same human as the previous centroid. If the
distance is above the threshold, we can assume that a new human has entered the
scene.
To implement centroid tracking in Python,
we can use the OpenCV library, which provides several functions for working
with contours and centroids. We can write a Python script that reads the input
video stream, performs human detection using the TensorFlow Object Detection
API, and then uses centroid tracking to count the number of humans in each
frame of the video.
Conclusion
In this article, we have explored how to
build a human detector and counter using Python with the help of data science.
We have seen how to use object detection techniques to detect the presence of
humans in an image or video stream, and how to use centroid tracking to count
the number of humans. By combining these techniques, we can build an automated
system for counting people that can greatly benefit industries such as
security, retail.
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