Description

The current repository is an implementation of detection method for low-performance Linux single-board computers. The method is used for detection of pedestrians, cyclists and vehicles in city environment. The method is based on analysis of geometrical object features in a foreground mask. The foreground mask is obtained using background subtraction algorithm. Classification is performed using logistic regression classifier. Implementation of the method is based on the publication “Fast Object Detection Using Dimensional Based Features for Public Street Environments”.

Prerequisites

The method can be used only when following conditions are satisfied:

1. Known intrinsic and extrinsic (angle about X axis and height of installation) camera parameters.
2. The camera is mounted on a static object.
3. The trained classifier for a particular usage scenario. The training uses 3D object models and camera parameters on input.

Usage

usage: run_detection.py [-h] [-c CLF] config

Run the lightweight detection algorithm

positional arguments:
  config             path to the configuration file

optional arguments:
  -h, --help         show this help message and exit
  -c CLF, --clf CLF  override path to the pickled classifier file given in
                     config

If the trained classifier is already existing and the camera has been calibrated, the algorithm can be run via:

python3 run_detection.py path_to_config.yml

Config structure

key	type	description
log_level	int	logging level: 10 - debug, 50 - critical
device	str	path to video device or file
resolution	list of ints	resolution (width, height) used for processing (1 - set as capturing resolution if it is supported by driver; 2 - resize captured frame to this resolution before processing)
fps	int	set capturing frame-per-second parameter if it is supported by driver
angle	int	camera incline towards to ground surface: 0 deg. - the camera is parallel to the ground surface; -90 deg. - camera points perpendicularly down
height	int	ground surface coordinates in meters relatively to a camera origin (e.g. -5 is 5m of camera height)
focal_length	int	camera focal length in mm
clf	str	path to the object containing the trained classifier
out_dir	str	output data such as logs, detection images, detection csv data will be stored in this directory
save_img	bool	enable or disable saving detection images with bounding rectangles and probabilities
save_csv	bool	enable or disable saving per-object detection information
stream	dict	define streaming parameters by keys: enabled - boolean to enable or disable streaming to rtsp streaming server, server - address:port of a rtsp streaming server
clahe_limit	int	value of contrast limiting for adaptive histogram equalization (see CLAHE)
bgs_method	dict	parameters of background subtraction method defined by keys: name - name of the method available in OpenCV (MOG2, KNN or CNT) , parameters - list of parameters passed to method constructor
dilate_it	int	number of times dilation is applied (dilates an image by using a specific structuring element)
time_window	int	number of samples defining periodicity of detection information printing (FPS, number of detections)
o_class_mapping	dict	mapping the integer object class to its string name of the following format: {class(int): class(string)}
sl_conn	dict	specifies parameters of connection to SL daemon by keys: detect_port - the port on which the detection application receives for messages from SL daemon, sl_port - the port of SL daemon to which the detection application sends messages, notif_interval - interval in seconds defining frequency of notifications sending to SL daemon
lamp_on_criteria	list of ints	sends signal to switch on lamp when the criteria is satisfied. List [q, N]: On how many N frames out of the last q frames target objects have been detected
lamp_switching_time	int	time required for a physical lamp to change its state
cont_area_thr	float	filter out small objects having contour area lower than the threshold (cont_area_thr): object_contour_area / (RES[0] * RES[1]) > cont_area_thr, set 0 to disable
extent_thr	float	filter out objects having extent lower than the threshold (extent_thr), set 0 to disable
max_distance	float	filter out objects detected on distances more than the threshold (max_distance), set 0 to disable
margin	int	filter out objects intersecting frame margin (left, right, up, down), set 0 to disable
base_res	list of ints	resolution used for calibration
camera_matrix	2D list of floats	camera intrinsics obtained via camera calibration
dist_coefs	2D list of floats	radial and tangential camera lens distortion coefficients
optimized_res	list of ints	resolution used for points reprojection after lens distortions removal
optimized_matrix	2D list of floats	camera intrinsics for points reprojection after lens distortions removal

Project structure

.
├── demo                            # Data for testing
│   ├── clf                         # Classifiers
│   │   ├── clf_name_1.pcl          # Pickled dictionary containing sklearn object
│   │   └── ...
│   ├── configs                         # Configuration files examples 
│   │   ├── config.yml                  
│   │   └── ...
├── prepare_img                     # Usefull scripts
└── requirements                    # Python packages lists

Related

1. Camera calibration
2. Camera matrix optimization
3. Classifier training
4. Bundle into a single executable
5. Streaming server

Cite

I. Matveev, K. Karpov, I. Chmielewski, E. Siemens, and A. Yurchenko, “Fast Object Detection Using Dimensional Based Features for Public Street Environments,” Smart Cities, vol. 3, no. 1, Art. no. 1, Mar. 2020, doi: 10.3390/smartcities3010006.