# This work is licensed under the MIT license. # Copyright (c) 2013-2023 OpenMV LLC. All rights reserved. # https://github.com/openmv/openmv/blob/master/LICENSE # # Absolute Optical Flow Translation # # This example shows off using your OpenMV Cam to measure translation # in the X and Y direction by comparing the current and a previous # image against each other. Note that only X and Y translation is # handled - not rotation/scale in this mode. # # To run this demo effectively please mount your OpenMV Cam on a steady # base and SLOWLY translate it to the left, right, up, and down and # watch the numbers change. Note that you can see displacement numbers # up +- half of the hoizontal and vertical resolution. # # NOTE You have to use a small power of 2 resolution when using # find_displacement(). This is because the algorithm is powered by # something called phase correlation which does the image comparison # using FFTs. A non-power of 2 resolution requires padding to a power # of 2 which reduces the usefulness of the algorithm results. Please # use a resolution like B64X64 or B64X32 (2x faster). # # Your OpenMV Cam supports power of 2 resolutions of 64x32, 64x64, # 128x64, and 128x128. If you want a resolution of 32x32 you can create # it by doing "img.scale(x_scale=0.5, y_scale=0.5, hint=image.AREA)" on a 64x64 image. import sensor import time sensor.reset() # Reset and initialize the sensor. sensor.set_pixformat(sensor.RGB565) # Set pixel format to RGB565 (or GRAYSCALE) sensor.set_framesize(sensor.B64X64) # Set frame size to 64x64... (or 64x32)... sensor.skip_frames(time=2000) # Wait for settings take effect. clock = time.clock() # Create a clock object to track the FPS. # Take from the main frame buffer's RAM to allocate a second frame buffer. # There's a lot more RAM in the frame buffer than in the MicroPython heap. # However, after doing this you have a lot less RAM for some algorithms... # So, be aware that it's a lot easier to get out of RAM issues now. extra_fb = sensor.alloc_extra_fb(sensor.width(), sensor.height(), sensor.RGB565) extra_fb.replace(sensor.snapshot()) while True: clock.tick() # Track elapsed milliseconds between snapshots(). img = sensor.snapshot() # Take a picture and return the image. # For this example we never update the old image to measure absolute change. displacement = extra_fb.find_displacement(img) # Offset results are noisy without filtering so we drop some accuracy. sub_pixel_x = int(displacement.x_translation() * 5) / 5.0 sub_pixel_y = int(displacement.y_translation() * 5) / 5.0 if ( displacement.response() > 0.1 ): # Below 0.1 or so (YMMV) and the results are just noise. print( "{0:+f}x {1:+f}y {2} {3} FPS".format( sub_pixel_x, sub_pixel_y, displacement.response(), clock.fps() ) ) else: print(clock.fps())