find_apriltags_3d_pose怎么矫正degrees(tag.y_rotation()输出的角度呢？

g5of

静止没什么问题，是测变化幅度不准，我把tag水平旋转一定角度，他测得的角度变化幅度(Ry变化度数)不对

kidswong999

kidswong999

kidswong999

kidswong999

我测试数据是正常的。
请提供你的图片。

# AprilTags Example
#
# This example shows the power of the OpenMV Cam to detect April Tags
# on the OpenMV Cam M7. The M4 versions cannot detect April Tags.

import sensor, image, time, math

sensor.reset()
sensor.set_pixformat(sensor.GRAYSCALE)
sensor.set_framesize(sensor.QQVGA) # we run out of memory if the resolution is much bigger...
sensor.skip_frames(time = 2000)
sensor.set_auto_gain(False)  # must turn this off to prevent image washout...
sensor.set_auto_whitebal(False)  # must turn this off to prevent image washout...
clock = time.clock()

# Note! Unlike find_qrcodes the find_apriltags method does not need lens correction on the image to work.

# What's the difference between tag families? Well, for example, the TAG16H5 family is effectively
# a 4x4 square tag. So, this means it can be seen at a longer distance than a TAG36H11 tag which
# is a 6x6 square tag. However, the lower H value (H5 versus H11) means that the false positve
# rate for the 4x4 tag is much, much, much, higher than the 6x6 tag. So, unless you have a
# reason to use the other tags families just use TAG36H11 which is the default family.

# The AprilTags library outputs the pose information for tags. This is the x/y/z translation and
# x/y/z rotation. The x/y/z rotation is in radians and can be converted to degrees. As for
# translation the units are dimensionless and you must apply a conversion function.

# f_x is the x focal length of the camera. It should be equal to the lens focal length in mm
# divided by the x sensor size in mm times the number of pixels in the image.
# The below values are for the OV7725 camera with a 2.8 mm lens.

# f_y is the y focal length of the camera. It should be equal to the lens focal length in mm
# divided by the y sensor size in mm times the number of pixels in the image.
# The below values are for the OV7725 camera with a 2.8 mm lens.

# c_x is the image x center position in pixels.
# c_y is the image y center position in pixels.

f_x = (2.8 / 3.984) * 160 # find_apriltags defaults to this if not set
f_y = (2.8 / 2.952) * 120 # find_apriltags defaults to this if not set
c_x = 160 * 0.5 # find_apriltags defaults to this if not set (the image.w * 0.5)
c_y = 120 * 0.5 # find_apriltags defaults to this if not set (the image.h * 0.5)

def degrees(radians):
    return (180 * radians) / math.pi

while(True):
    clock.tick()
    img = sensor.snapshot()
    for tag in img.find_apriltags(fx=f_x, fy=f_y, cx=c_x, cy=c_y): # defaults to TAG36H11
        img.draw_rectangle(tag.rect(), color = (255, 0, 0))
        img.draw_cross(tag.cx(), tag.cy(), color = (0, 255, 0))
        # Translation units are unknown. Rotation units are in degrees.
        img.draw_string(0,0,"Rx %f" % degrees(tag.x_rotation()))
        img.draw_string(0,10,"Ry %f" % degrees(tag.y_rotation()))
        img.draw_string(0,20,"Rz %f" % degrees(tag.z_rotation()))
        img.draw_string(0,90,"Rx %f" % tag.x_translation())
        img.draw_string(0,100,"Ry %f" % tag.y_translation())
        img.draw_string(0,110,"Rz %f" % tag.z_translation())
        #print("Rx %f, Ry %f, Rz %f" % print_args)
    #print(clock.fps())

g5of

@kidswong999

g5of

@kidswong999
我在Ry方向间隔10度变化一次，测得的Ry变化角度不对，请教该怎么调呢

kidswong999

Ry哪里不对？？

g5of

三张图片里Ry的实际值分别应该是360.10.20左右，但测得的是360,15,30左右,就是说，第一张图片里Ry应该是20左右,第二张图片里应该是10左右才对

kidswong999

我怎么觉得这属于仪器的精度。

比如OpenMV的水平精度。apriltag的位置精度，角度你是用的什么仪器摆放的？

g5of

仪器精度误差没这么大，openmv固定还算准，Apriltag摆放角度是拿量角器量的，误差都没这么大。
你测得是准的嘛，你用的程序是上面那个吗，我试了试更离谱，难道我用的镜头不适用这俩程序？