scripts/npzs_to_frame.py

"""
convert the event file to frame (npy file).
"""
import argparse
from pathlib import Path
import numpy as np
from tqdm import tqdm
import numba
import cv2 as cv

parser = argparse.ArgumentParser(description="Convert the event file to frame.")
parser.add_argument("--input", type=str, help="the path of npz files.")
parser.add_argument("--timestamp", type=str, help="the path of timestamp files.")
parser.add_argument("--output", type=str, help="the dir of out event.")
parser.add_argument("--rgb", type=str, help="the dir of rgb frames.")
parser.add_argument("--sort_by_num", action="store_true", help="sort by number.")
parser.add_argument("--winsz", type=int, default=5, help="the window size of event frame.")
args = parser.parse_args()

@numba.jit()
def accumulate_events(xs, ys, ps, size, ev_frame = None, resolution_level=1, polarity_offset=0):
    if ev_frame is None:
        ev_frame = np.zeros(size, dtype=np.float32)
    for i in range(len(xs)):
        x, y, p = xs[i], ys[i], ps[i]
        ev_frame[y // resolution_level, x // resolution_level] += (p + polarity_offset)
    return ev_frame

def get_info(timestamp_path, npz_path, rgb_path, sort_by_num=False):
    timestamps = np.loadtxt(timestamp_path)
    npz_list = list(Path(npz_path).iterdir())
    image_list = list(Path(rgb_path).iterdir())

    size = cv.imread(str(image_list[0])).shape[:2]
    ev_list = [str(rgb.stem) for rgb in image_list]

    if sort_by_num:
        ev_list = sorted(ev_list, key=lambda x: int(x))
        npz_list = sorted(npz_list, key=lambda x: int(x.stem))
    else:
        ev_list = sorted(ev_list)
        npz_list = sorted(npz_list)

    return timestamps, npz_list, ev_list, size

if __name__ == "__main__":
    print(args)

    out_path = Path(args.output)
    out_path.mkdir(parents=True, exist_ok=True)
    timestamps, npz_list, ev_list, size = get_info(args.timestamp, args.input, args.rgb, args.sort_by_num)
    num_cam = len(ev_list)
    print(f"=== start convert {args.input}, winsz {args.winsz}, {num_cam} frames, size {size},  npzs {len(npz_list)} ===")

    for i in tqdm(range(num_cam-2, num_cam-1)):  # [winsz, num_cam-1]
        start_time = max(0, i - args.winsz) / (num_cam - 1)
        end_time = i / (num_cam - 1)
        assert start_time <= end_time

        start = np.searchsorted(timestamps, start_time * timestamps.max())
        end = np.searchsorted(timestamps, end_time * timestamps.max())

        ev_frame = np.zeros(size, dtype=np.float32)
        print(f"start {start}, end {end}, {end-start}")
        for npz_path in npz_list[start:end]:
            print(npz_path)
            ev_data = np.load(npz_path)
            ev_frame = accumulate_events(ev_data["x"], ev_data["y"], ev_data["p"], size, ev_frame)
        np.save(out_path / str(ev_list[i]), ev_frame)