<|file_name|>image-patches-differential-rotation-scale.py<|end_file_name|><｜fim▁begin｜># Image Patches Differential Optical Flow Rotation/Scale
#
# This example shows off using your OpenMV Cam to measure
# rotation/scale by comparing the current and the previous
# image against each other. Note that only rotation/scale is
# handled - not X and Y translation in this mode.
#
# However, this examples goes beyond doing optical flow on the whole
# image at once. Instead it breaks up the process by working on groups
# of pixels in the image. This gives you a "new" image of results.<｜fim▁hole｜># algorithm to work. A featureless surface produces crazy results.

# NOTE: Unless you have a very nice test rig this example is hard to see usefulness of...

BLOCK_W = 16 # pow2
BLOCK_H = 16 # pow2

# To run this demo effectively please mount your OpenMV Cam on a steady
# base and SLOWLY rotate the camera around the lens and move the camera
# forward/backwards to see the numbers change.
# I.e. Z direction changes only.

import sensor, image, time, math

# 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 B128X128 or B128X64 (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.pool(2, 2)" on a 64x64 image.

sensor.reset()                         # Reset and initialize the sensor.
sensor.set_pixformat(sensor.GRAYSCALE) # Set pixel format to GRAYSCALE (or RGB565)
sensor.set_framesize(sensor.B128X128)  # Set frame size to 128x128... (or 128x64)...
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.GRAYSCALE)
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 y in range(0, sensor.height(), BLOCK_H):
        for x in range(0, sensor.width(), BLOCK_W):
            displacement = extra_fb.find_displacement(img, logpolar=True, \
                roi = (x, y, BLOCK_W, BLOCK_H), template_roi = (x, y, BLOCK_W, BLOCK_H))

            # Below 0.1 or so (YMMV) and the results are just noise.
            if(displacement.response() > 0.1):
                rotation_change = displacement.rotation()
                zoom_amount = 1.0 + displacement.scale()
                pixel_x = x + (BLOCK_W//2) + int(math.sin(rotation_change) * zoom_amount * (BLOCK_W//4))
                pixel_y = y + (BLOCK_H//2) + int(math.cos(rotation_change) * zoom_amount * (BLOCK_H//4))
                img.draw_line((x + BLOCK_W//2, y + BLOCK_H//2, pixel_x, pixel_y), \
                    color = 255)
            else:
                img.draw_line((x + BLOCK_W//2, y + BLOCK_H//2, x + BLOCK_W//2, y + BLOCK_H//2), \
                    color = 0)
    extra_fb.replace(img)

    print(clock.fps())<｜fim▁end｜>
#
# NOTE that surfaces need to have some type of "edge" on them for the