openmv之测距

通过openmv来进行测距的两种办法

第一就是通过ApriTag的3D定位进行测距

第二就是通过利用参照物进行测距

 通过上图可以看出实际距离和物体的像素大小成反比

如何得到常数k就是需要解决的问题

先将物体放在固定的距离x，然后打印出物体的像素大小y，就可以得到常数k

k = x*y

# Measure the distance
#
# This example shows off how to measure the distance through the size in imgage
# This example in particular looks for yellow pingpong ball.

import sensor, image, time

# For color tracking to work really well you should ideally be in a very, very,
# very, controlled enviroment where the lighting is constant...
yellow_threshold   = ( 56,   83,    5,   57,   63,   80)
# You may need to tweak the above settings for tracking green things...
# Select an area in the Framebuffer to copy the color settings.

sensor.reset() # Initialize the camera sensor.
sensor.set_pixformat(sensor.RGB565) # use RGB565.
sensor.set_framesize(sensor.QQVGA) # use QQVGA for speed.
sensor.skip_frames(10) # Let new settings take affect.
sensor.set_auto_whitebal(False) # turn this off.
clock = time.clock() # Tracks FPS.

K=5000#the value should be measured
#k = 物体放置距离 × 打印的Lx 

while(True):
    clock.tick() # Track elapsed milliseconds between snapshots().
    img = sensor.snapshot() # Take a picture and return the image.

    blobs = img.find_blobs([yellow_threshold])
    if len(blobs) == 1:
        # Draw a rect around the blob.
        b = blobs[0]
        img.draw_rectangle(b[0:4]) # rect
        img.draw_cross(b[5], b[6]) # cx, cy
        Lx = (b[2]+b[3])/2
        print(Lx)
        length = K/Lx
        print(length)

    #print(clock.fps()) # Note: Your OpenMV Cam runs about half as fast while
    # connected to your computer. The FPS should increase once disconnected.

根据上面代码先将物体放置在固定位置，例如10cm，然后打印出该物体在openmv中的像素值Lx

可以得出k =10 * Lx

然后就可以对物体进行测距

对于Lx 的计算是先通过将捕捉的物体颜色范围的色块，然后通过b[2]色块的宽和b[3]色块的高取的物体的平均半径

参考文章 https://blog.csdn.net/qq_42518517/article/details/101059853