calib.py

calib.py

import math

from kivy.core.window import Window
from kivy.graphics.transformation import Matrix
from kivy.vector import Vector

CALIBRATION_MATRIX = Matrix()

# Calibration angle: -1.5758043422592645
# Calibration scale: [1.373241596109775, -1.040252303237079]
touches = [
    (181.9474425364121, 1119.759678282034),
    (1694.8342158120147, 1078.1402981296671),
    (1611.2928374331036, 5.0781189019419095),
]


def calibrate(touches):
    global CALIBRATION_MATRIX
    window_width, window_height = 1920, 1200

    bottom_left, bottom_right, top_right = touches

    matrix = Matrix()
    matrix.set(array=[
        [
            # Difference between (1, 0) and (0, 0)
            bottom_right[0] - bottom_left[0],
            bottom_right[1] - bottom_left[1],
            0.0,
            0.0,
        ],
        [
            # Difference between (0, 1) and (0, 0)
            top_right[0] - bottom_right[0],
            top_right[1] - bottom_right[1],
            0.0,
            0.0,
        ],
        [
            0.0,
            0.0,
            1.0,
            0.0,
        ],
        [
            # Translation
            bottom_left[0],
            bottom_left[1],
            0.0,
            1.0,
        ],
    ])
    CALIBRATION_MATRIX = Matrix().scale(
        window_width,
        window_height,
        1.0
    ).multiply(matrix.inverse())


calibrate(touches)
calibrated_bottom_left = CALIBRATION_MATRIX.transform_point(*touches[0], 0)[:2]
# Expected: approximately 0.0, 0.0
# Actual: New bottom left: (71.05832720228668, 113.49659082270978)
print('New bottom left:', calibrated_bottom_left)

calibrated_bottom_right = CALIBRATION_MATRIX.transform_point(
    *touches[1],
    0,
)[:2]
# Expected: approximately 1920.0, 0.0
# Actual: New bottom right: (2149.022258748923, 99.6430240209063)
print('New bottom right:', calibrated_bottom_right)

calibrated_top_right = CALIBRATION_MATRIX.transform_point(
    *touches[2],
    0,
)[:2]
# Expected: approximately 1920.0, 1200.0
# Actual: New top right: (2065.039622336423, 1218.6310907894283)
print('New top right:', calibrated_top_right)