Dual-fisheye to Equirectangular Converter using OpenCV remap

dualfisheye.py

# Dual-fisheye to Equirectangular Converter using OpenCV remap
import sys
import numpy as np
import cv2

try:
    # try to load map file
    xmap = np.load("xmap.npy")
    ymap = np.load("ymap.npy")
except IOError:
    # if the map files are not exist, generate new map files.
    print("Generating map miles...")
    COLS = 1280
    ROWS = 720
    xmap = np.zeros((ROWS, COLS), np.float32)
    ymap = np.zeros((ROWS, COLS), np.float32)
    DST_X = float(COLS)
    DST_Y = DST_X / 2
    SRC_CX1 = DST_X / 4
    SRC_CX2 = DST_X - SRC_CX1
    SRC_CY = DST_X / 4
    SRC_R = 0.884 * DST_X / 4
    SRC_RX = SRC_R * 1.00
    SRC_RY = SRC_R * 1.00
    #
    for y in range(COLS // 2):
        for x in range(COLS):
            ph1 = np.pi * x / DST_Y
            th1 = np.pi * y / DST_Y

            x1 = np.sin(th1) * np.cos(ph1)
            y1 = np.sin(th1) * np.sin(ph1)
            z1 = np.cos(th1)

            ph2 = np.arccos(-x1)
            th2 = (1 if y1 >= 0 else -1) * np.arccos(-z1 / np.sqrt(y1 * y1 + z1 * z1))

            if ph2 < np.pi / 2:
                r0 = ph2 / (np.pi / 2)
                xmap[y,x] = SRC_RX * r0 * np.cos(th2) + SRC_CX1
                ymap[y,x] = SRC_RY * r0 * np.sin(th2) + SRC_CY
            else:
                r0 = (np.pi - ph2) / (np.pi / 2)
                xmap[y,x] = SRC_RX * r0 * np.cos(np.pi - th2) + SRC_CX2
                ymap[y,x] = SRC_RY * r0 * np.sin(np.pi - th2) + SRC_CY

    np.save("xmap.npy", xmap)
    np.save("ymap.npy", ymap)

def convert_dualfisheye_to_equirectangular(frmae):
    return cv2.remap(frame, xmap, ymap, cv2.INTER_LINEAR, cv2.BORDER_CONSTANT)

if __name__ == '__main__':
    if len(sys.argv) < 3:
        print('Usage: Python3 dualfisheye.py <inputfile> <outputfile>')
        sys.exit(1)
    cap = cv2.VideoCapture(sys.argv[1])
    if not cap.isOpened():
        print('file not opened')
        sys.exit(1)
    fps    = cap.get(cv2.CAP_PROP_FPS)
    height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
    width  = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
    fourcc = cv2.VideoWriter_fourcc('m', 'p', '4', 'v')
    out = cv2.VideoWriter(sys.argv[2], fourcc, fps, (int(width), int(height)))
    count = 0
    while(cap.isOpened()):
        ret, frame = cap.read()
        if ret == False:
            break
        frame = convert_dualfisheye_to_equirectangular(frame)
        out.write(frame)

        if count % 30 == 0:
            print('.', end="")
            sys.stdout.flush()
        count += 1

    print()
    cap.release()
    cv2.destroyAllWindows()