V831

Preface

AprilTag Tag tracking is a commonly used visual tag ,V831 It also has this function .

One 、AprilTag Mark tracking ranging

Look at the code first

#!/usr/bin/python3
from maix import display, camera 

f_x = (6 / 5.76) * 240 #  The focal length of the lens is 6MM, photosensitive cmos What's your length 5.76mm,240 Pixels are the length of the screen 
f_y = (6 / 3.24) * 240 #  The focal length of the lens is 6MM, photosensitive cmos The width of 3.24mm,240 Pixels are the width of the screen 

c_x = 240 * 0.5  #  Half the screen resolution 
c_y = 240 * 0.5  #  Half the screen resolution 

while True:
    t = camera.capture()
    mks = t.find_apriltags(families = 16,fx = f_x,fy = f_y,cx = c_x,cy = c_y)
    for mk in mks:
      x_tran = mk['x_translation']
      y_tran = mk['y_translation']
      z_tran = mk['z_translation']
      # Family information 
      fam = mk['family']
      # Outline data 
      x, y, w, h, id  =  mk['x'], mk['y'], mk['w'], mk['h'], mk['id']
      # Inner frame data 
      x1,y1 = mk['corners'][0]   # Access the list of dictionaries 
      x2,y2 = mk['corners'][1]
      x3,y3 = mk['corners'][2]
      x4,y4 = mk['corners'][3]
      z1,z2 = mk['centroid']
      # Virtual distance 
      length = (x_tran*x_tran + y_tran*y_tran + z_tran*z_tran)**0.5

      # Draw frame 
      t.draw_rectangle(x, y, x + w, y + h, color=(0, 0, 255), thickness = 2) 
      # Print ID
      t.draw_string(int(x + w*0.15) , int(y + h*0.15) , str(id), scale = 4.0, color = (255, 0, 0), thickness = 3)  
      # Draw the inner frame 
      t.draw_line(x1, y1, x2, y2, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x2, y2, x3, y3, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x3, y3, x4, y4, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x4, y4, x1, y1, color = (0, 255, 0), thickness = 3)  
      
      if(fam == 16):
        t.draw_string(x, y-20, "TAG36H11", scale = 1.0, color = (255, 0, 0), thickness = 2)
      
      t.draw_string(x, y+h+15, str(int(length * 3.0649 - 2))+" cm", scale = 1.0, color = (255, 0, 0), thickness = 2)  

    display.show(t)

If you want to obtain the coordinates of the four points of the label, you only need to obtain the key value in the dictionary as corners The value in the list of , And want to get the outline ( Blue box ) You only need to get the key value in the dictionary as x , y , w , h The value of , Finally, just like the operation in the code .

The key values of the dictionary are as follows ： ‘x’ , ‘y’ , ‘w’ , ‘h’ , ‘id’ , ‘family’ , ‘centroid’ , ‘corners’ , ‘x_translation’ , ‘y_translation’ , ‘z_translation’ , ‘decision_margin’ , ‘hamming’ , ‘goodness’ , ‘x_rotation’ , ‘y_rotation’ , ‘z_rotation’.

Introduce the meaning of several key values .‘x’ , ‘y’ , ‘w’ , ‘h’ The values returned by the key values are the upper left corner of the outer frame x Coordinates and y Coordinates and the length and width of the outer frame . Pay special attention to the key value ‘corners’ It returns a list , The values in the list represent the coordinates of the four vertices of the inner box .

In this code, the principle of ranging is also similar to small hole imaging , You can see the previous ranging blog about how to use it , I know this value is not very accurate （ It may be due to tracking and ranging ）, I will optimize this ranging algorithm later .

Two 、 AprilTag Obtain angle information and display of three-dimensional coordinates

Also look at the code first

#!/usr/bin/python3
from maix import display, camera 
import math

f_x = (6 / 5.76) * 240 #  The focal length of the lens is 6MM, photosensitive cmos What's your length 5.76mm,240 Pixels are the length of the screen 
f_y = (6 / 3.24) * 240 #  The focal length of the lens is 6MM, photosensitive cmos The width of 3.24mm,240 Pixels are the width of the screen 

c_x = 240 * 0.5 #  Half the screen resolution 
c_y = 240 * 0.5 #  Half the screen resolution 

while True:
    t = camera.capture()
    mks = t.find_apriltags(families = 16,fx = f_x,fy = f_y,cx = c_x,cy = c_y)
    for mk in mks:

      # Inner frame data 
      x1,y1 = mk['corners'][0]   # Access the list of dictionaries 
      x2,y2 = mk['corners'][1]
      x3,y3 = mk['corners'][2]
      x4,y4 = mk['corners'][3]
      
      # Get angle information 
      x_rol = mk['x_rotation']
      y_rol = mk['y_rotation']
      z_rol = mk['z_rotation']
      # Draw the inner frame 
      t.draw_line(x1, y1, x2, y2, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x2, y2, x3, y3, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x3, y3, x4, y4, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x4, y4, x1, y1, color = (0, 255, 0), thickness = 3)  
    
      # Displays the current angle 
      t.draw_string(2, 2, "X rotation is: "+str(int(180*x_rol/3.14))+" Angle", scale = 1.0, color = (0, 0, 255), thickness = 1)    #90° ~ 270°   Directly opposite is 180°. Up and down 
      t.draw_string(2, 15, "Y rotation is: "+str(int(180*y_rol/3.14))+" Angle", scale = 1.0, color = (0, 0, 255), thickness = 1)   #0° ~ 90°,270° ~ 360°    Directly opposite is 0°.  about 
      t.draw_string(2, 30, "Z rotation is: "+str(int(180*z_rol/3.14))+" Angle", scale = 1.0, color = (0, 0, 255), thickness = 1)   #0° ~ 360°    Directly opposite is 0°.  Clockwise rotation increases     

      # Picture frame in the lower right corner 
      t.draw_string(140, 120, "Space", scale = 1.0, color = (125, 0, 0), thickness = 2)  
      t.draw_rectangle(140, 140, 235, 235, color=(128, 128, 128), thickness=2) 
      
      # Draw a three-dimensional coordinate system 
      t.draw_line(180, 200, int(180 - 40 * math.sin(z_rol)), int(240 - 40 * math.cos(z_rol) + 40 * math.cos(x_rol)), color = (255, 0, 0), thickness = 3)   
      t.draw_line(180, 200, int(140 + 40 * math.cos(z_rol) + 40 * math.cos(y_rol)), int(200 - 40 * math.sin(z_rol)), color = (0, 255, 0), thickness = 3) 
      t.draw_line(180, 200, int(180 + 40 * math.sin(y_rol)),int(200 - 40 * math.sin(x_rol)), color = (0, 0, 255), thickness = 3) 

    display.show(t)

If you want to get the angle information of the label, you only need to get the key values in the dictionary are x_rotation,y_rotation,z_rotation The value of , It should be pointed out that the obtained value is radian , If you need to convert it into an angle, you need to use the radian to angle formula . Multiply the obtained radian by 180 Divided by 3.14 that will do （3.14 Two decimal places of PI are selected ）.

x_rotation The value range after changing to angle is [90°,270°] When facing the label, it is displayed as 180° , Changes as the label moves back and forth . y_rotation The value range after changing to angle is [0°,90°]U[270°,360°] When facing the label, it is displayed as 0° , Changes when the label moves left and right .z_rotation The value range after changing to angle is [0°,360°] When facing the label, it is displayed as 0° , Changes as the label rotates .

3、 ... and 、AprilTag Display of multiple three-dimensional coordinates

from maix import display, camera 
import math

f_x = (6 / 5.76) * 240 
f_y = (6 / 3.24) * 240 

c_x = 240 * 0.5 
c_y = 240 * 0.5 

while True:
    t = camera.capture()
    mks = t.find_apriltags(families = 16,fx = f_x,fy = f_y,cx = c_x,cy = c_y)
    for mk in mks:

      # Inner frame data 
      x1,y1 = mk['corners'][0]   # Access the list of dictionaries 
      x2,y2 = mk['corners'][1]
      x3,y3 = mk['corners'][2]
      x4,y4 = mk['corners'][3]
      
      x_rol = mk['x_rotation']
      y_rol = mk['y_rotation']
      z_rol = mk['z_rotation']
      # Draw the inner frame 
      t.draw_line(x1, y1, x2, y2, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x2, y2, x3, y3, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x3, y3, x4, y4, color = (0, 255, 0), thickness = 3)  
      t.draw_line(x4, y4, x1, y1, color = (0, 255, 0), thickness = 3)  
    
      
      t.draw_string(x4, y4, "xR: "+str(int(180*x_rol/3.14)), scale = 1.0, color = (255, 0, 0), thickness = 2)    #90° ~ 270°   Directly opposite is 180°. Up and down 
      t.draw_string(x4, y4 + 15, "yR: "+str(int(180*y_rol/3.14)), scale = 1.0, color = (255, 0, 0), thickness = 2)   #0° ~ 90°,270° ~ 360°    Directly opposite is 0°.  about 
      t.draw_string(x4, y4 + 30, "zR: "+str(int(180*z_rol/3.14)), scale = 1.0, color = (255, 0, 0), thickness = 2)   #0° ~ 360°    Directly opposite is 0°.  Clockwise rotation increases 
      
      t.draw_line(x4, y4, int(x4 - 40 * math.sin(z_rol)), int(y4 + 40 - 40 * math.cos(z_rol) + 40 * math.cos(x_rol)), color = (255, 0, 0), thickness = 3)   
      t.draw_line(x4, y4, int(x4 - 40 + 40 * math.cos(z_rol) + 40 * math.cos(y_rol)), int(y4 - 40 * math.sin(z_rol)), color = (0, 0, 0), thickness = 3) 
      t.draw_line(x4, y4, int(x4  + 40 * math.sin(y_rol)),int(y4 - 40 * math.sin(x_rol)), color = (0, 0, 255), thickness = 3) 
    display.show(t)

summary

Feeling plus one jy-901 gyroscope ,V831 Can play his function infinitely .