Welcome to ROSMASTER M3 PRO repository

Depth pseudo-color image

1. Content Description

This section subscribes to the Deep Color Image topic and uses OpenCV image processing to convert a black-and-white depth image into a pseudo-color image.

This section requires entering commands in the terminal. The terminal you open depends on your motherboard type. This lesson uses the Raspberry Pi 5 as an example. For Raspberry Pi and Jetson-Nano boards, you need to open a terminal on the host computer and enter the command to enter the Docker container. Once inside the Docker container, enter the commands mentioned in this section in the terminal. For instructions on entering the Docker container from the host computer, refer to this product tutorial [Configuration and Operation Guide]--[Enter the Docker (Jetson Nano and Raspberry Pi 5 users, see here)].

Simply open the terminal on the Orin motherboard and enter the commands mentioned in this section.

2. Program startup

First, in the terminal, enter the following command to start the camera,

ros2 launch orbbec_camera dabai_dcw2.launch.py

After successfully starting the camera, open another terminal and enter the following command in the terminal to start the deep pseudo-color image conversion program:

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ros2 run yahboom_M3Pro_DepthCam GetDepthColor

After startup, as shown below,

Different colors indicate the difference in depth information.

3. Core code analysis

Program code path:

• Raspberry Pi 5 and Jetson-Nano board

  The program code is in the running docker. The path in docker is/root/yahboomcar_ws/src/yahboom_M3Pro_DepthCam/yahboom_M3Pro_DepthCam/GetDepthColor.py

• Orin Motherboard

  The program code path is,/home/jetson/yahboomcar_ws/yahboom_M3Pro_DepthCam/yahboom_M3Pro_DepthCam/GetDepthColor.py

Import the library files used

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from cv_bridge import CvBridge
import cv2
from rclpy.node import Node
import rclpy
from sensor_msgs.msg import Image

Defines the depth image decoding format

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encoding = ['16UC1', '32FC1']

Define subscribers and define deep image topics

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self.sub_depth = self.create_subscription(Image,"/camera/depth/image_raw",self.get_DepthImgCallBack,100)

Define self.depth_bridge to convert the message format into an image format that openc can handle

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self.depth_bridge = CvBridge()

Convert image data message into image

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depth_image = self.depth_bridge.imgmsg_to_cv2(depth_frame, encoding[1])

Call the opencv image processing function cv2.applyColorMap to convert the depth map

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depth_to_color_image = cv2.applyColorMap(cv2.convertScaleAbs(depth_image, alpha=1.0), cv2.COLORMAP_JET)

cv2.convertScaleAbs: performs a linear transformation on the image data and converts it to 8-bit unsigned integer (uint8) format with the scaling factor being the scaling factor.

cv2.applyColorMap: A function that converts a single-channel grayscale image to a pseudo-color image (Pseudo-color) , enhancing the visualization effect through color mapping. This parameter has two variables, the first variable is a single-channel 8-bit or floating-point image (grayscale image), and the second variable is a color map. The following values are optional:

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cv2.COLORMAP_AUTUMN # red -orange-yellow         
cv2.COLORMAP_BONE #Black-white (grayscale with a bluish tint )           
cv2.COLORMAP_HSV #HSV color space            
cv2.COLORMAP_JET #Blue- cyan -yellow-red (classic heat map )            
cv2.COLORMAP_WINTER #    blue -green      
cv2.COLORMAP_RAINBOW #Rainbow    color (red-purple )     
cv2.COLORMAP_OCEAN #dark blue-light blue          
cv2.COLORMAP_SUMMER # green -yellow         
cv2.COLORMAP_SPRING # Magenta - yellow         
cv2.COLORMAP_COOL #cyan - magenta           
cv2.COLORMAP_HSV #HSV color space cycle            
cv2.COLORMAP_PINK #pink tone           
cv2.COLORMAP_PARULA #MATLAB Parula style         
cv2.COLORMAP_VIRIDIS #Modern scientific color scale (green-purple)        
cv2.COLORMAP_INFERNO # Black -Red-Yellow-White (high contrast )        
cv2.COLORMAP_PLASMA # purple -red-yellow         
cv2.COLORMAP_MAGMA # black -red-white          
cv2.COLORMAP_TWILIGHT # blue -pink - white gradient