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import itertools
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from glob import glob
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from math import ceil
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from pathlib import Path
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import cv2
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import numpy as np
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from PIL import Image
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from tqdm import tqdm
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from ultralytics.data.utils import exif_size, img2label_paths
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from ultralytics.utils.checks import check_requirements
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check_requirements("shapely")
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from shapely.geometry import Polygon
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def bbox_iof(polygon1, bbox2, eps=1e-6):
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"""
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Calculate Intersection over Foreground (IoF) between polygons and bounding boxes.
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Args:
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polygon1 (np.ndarray): Polygon coordinates, shape (n, 8).
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bbox2 (np.ndarray): Bounding boxes, shape (n, 4).
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eps (float, optional): Small value to prevent division by zero. Defaults to 1e-6.
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Returns:
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(np.ndarray): IoF scores, shape (n, 1) or (n, m) if bbox2 is (m, 4).
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Note:
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Polygon format: [x1, y1, x2, y2, x3, y3, x4, y4].
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Bounding box format: [x_min, y_min, x_max, y_max].
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"""
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polygon1 = polygon1.reshape(-1, 4, 2)
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lt_point = np.min(polygon1, axis=-2)
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rb_point = np.max(polygon1, axis=-2)
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bbox1 = np.concatenate([lt_point, rb_point], axis=-1)
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lt = np.maximum(bbox1[:, None, :2], bbox2[..., :2])
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rb = np.minimum(bbox1[:, None, 2:], bbox2[..., 2:])
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wh = np.clip(rb - lt, 0, np.inf)
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h_overlaps = wh[..., 0] * wh[..., 1]
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left, top, right, bottom = (bbox2[..., i] for i in range(4))
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polygon2 = np.stack([left, top, right, top, right, bottom, left, bottom], axis=-1).reshape(-1, 4, 2)
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sg_polys1 = [Polygon(p) for p in polygon1]
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sg_polys2 = [Polygon(p) for p in polygon2]
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overlaps = np.zeros(h_overlaps.shape)
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for p in zip(*np.nonzero(h_overlaps)):
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overlaps[p] = sg_polys1[p[0]].intersection(sg_polys2[p[-1]]).area
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unions = np.array([p.area for p in sg_polys1], dtype=np.float32)
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unions = unions[..., None]
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unions = np.clip(unions, eps, np.inf)
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outputs = overlaps / unions
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if outputs.ndim == 1:
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outputs = outputs[..., None]
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return outputs
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def load_yolo_dota(data_root, split="train"):
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"""
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Load DOTA dataset.
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Args:
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data_root (str): Data root.
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split (str): The split data set, could be train or val.
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Notes:
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The directory structure assumed for the DOTA dataset:
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- data_root
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- images
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- train
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- val
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- labels
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- train
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- val
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"""
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assert split in {"train", "val"}, f"Split must be 'train' or 'val', not {split}."
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im_dir = Path(data_root) / "images" / split
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assert im_dir.exists(), f"Can't find {im_dir}, please check your data root."
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im_files = glob(str(Path(data_root) / "images" / split / "*"))
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lb_files = img2label_paths(im_files)
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annos = []
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for im_file, lb_file in zip(im_files, lb_files):
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w, h = exif_size(Image.open(im_file))
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with open(lb_file) as f:
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lb = [x.split() for x in f.read().strip().splitlines() if len(x)]
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lb = np.array(lb, dtype=np.float32)
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annos.append(dict(ori_size=(h, w), label=lb, filepath=im_file))
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return annos
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def get_windows(im_size, crop_sizes=(1024,), gaps=(200,), im_rate_thr=0.6, eps=0.01):
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"""
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Get the coordinates of windows.
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Args:
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im_size (tuple): Original image size, (h, w).
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crop_sizes (List(int)): Crop size of windows.
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gaps (List(int)): Gap between crops.
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im_rate_thr (float): Threshold of windows areas divided by image ares.
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eps (float): Epsilon value for math operations.
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"""
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h, w = im_size
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windows = []
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for crop_size, gap in zip(crop_sizes, gaps):
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assert crop_size > gap, f"invalid crop_size gap pair [{crop_size} {gap}]"
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step = crop_size - gap
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xn = 1 if w <= crop_size else ceil((w - crop_size) / step + 1)
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xs = [step * i for i in range(xn)]
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if len(xs) > 1 and xs[-1] + crop_size > w:
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xs[-1] = w - crop_size
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yn = 1 if h <= crop_size else ceil((h - crop_size) / step + 1)
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ys = [step * i for i in range(yn)]
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if len(ys) > 1 and ys[-1] + crop_size > h:
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ys[-1] = h - crop_size
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start = np.array(list(itertools.product(xs, ys)), dtype=np.int64)
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stop = start + crop_size
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windows.append(np.concatenate([start, stop], axis=1))
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windows = np.concatenate(windows, axis=0)
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im_in_wins = windows.copy()
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im_in_wins[:, 0::2] = np.clip(im_in_wins[:, 0::2], 0, w)
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im_in_wins[:, 1::2] = np.clip(im_in_wins[:, 1::2], 0, h)
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im_areas = (im_in_wins[:, 2] - im_in_wins[:, 0]) * (im_in_wins[:, 3] - im_in_wins[:, 1])
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win_areas = (windows[:, 2] - windows[:, 0]) * (windows[:, 3] - windows[:, 1])
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im_rates = im_areas / win_areas
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if not (im_rates > im_rate_thr).any():
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max_rate = im_rates.max()
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im_rates[abs(im_rates - max_rate) < eps] = 1
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return windows[im_rates > im_rate_thr]
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def get_window_obj(anno, windows, iof_thr=0.7):
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"""Get objects for each window."""
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h, w = anno["ori_size"]
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label = anno["label"]
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if len(label):
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label[:, 1::2] *= w
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label[:, 2::2] *= h
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iofs = bbox_iof(label[:, 1:], windows)
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return [(label[iofs[:, i] >= iof_thr]) for i in range(len(windows))]
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else:
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return [np.zeros((0, 9), dtype=np.float32) for _ in range(len(windows))]
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def crop_and_save(anno, windows, window_objs, im_dir, lb_dir, allow_background_images=True):
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"""
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Crop images and save new labels.
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Args:
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anno (dict): Annotation dict, including `filepath`, `label`, `ori_size` as its keys.
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windows (list): A list of windows coordinates.
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window_objs (list): A list of labels inside each window.
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im_dir (str): The output directory path of images.
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lb_dir (str): The output directory path of labels.
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allow_background_images (bool): Whether to include background images without labels.
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Notes:
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The directory structure assumed for the DOTA dataset:
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- data_root
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- images
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- train
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- val
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- labels
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- train
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- val
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"""
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im = cv2.imread(anno["filepath"])
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name = Path(anno["filepath"]).stem
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for i, window in enumerate(windows):
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x_start, y_start, x_stop, y_stop = window.tolist()
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new_name = f"{name}__{x_stop - x_start}__{x_start}___{y_start}"
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patch_im = im[y_start:y_stop, x_start:x_stop]
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ph, pw = patch_im.shape[:2]
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label = window_objs[i]
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if len(label) or allow_background_images:
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cv2.imwrite(str(Path(im_dir) / f"{new_name}.jpg"), patch_im)
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if len(label):
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label[:, 1::2] -= x_start
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label[:, 2::2] -= y_start
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label[:, 1::2] /= pw
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label[:, 2::2] /= ph
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with open(Path(lb_dir) / f"{new_name}.txt", "w") as f:
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for lb in label:
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formatted_coords = [f"{coord:.6g}" for coord in lb[1:]]
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f.write(f"{int(lb[0])} {' '.join(formatted_coords)}\n")
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def split_images_and_labels(data_root, save_dir, split="train", crop_sizes=(1024,), gaps=(200,)):
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"""
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Split both images and labels.
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Notes:
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The directory structure assumed for the DOTA dataset:
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- data_root
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- images
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- split
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- labels
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- split
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and the output directory structure is:
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- save_dir
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- images
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- split
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- labels
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- split
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"""
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im_dir = Path(save_dir) / "images" / split
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im_dir.mkdir(parents=True, exist_ok=True)
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lb_dir = Path(save_dir) / "labels" / split
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lb_dir.mkdir(parents=True, exist_ok=True)
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annos = load_yolo_dota(data_root, split=split)
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for anno in tqdm(annos, total=len(annos), desc=split):
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windows = get_windows(anno["ori_size"], crop_sizes, gaps)
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window_objs = get_window_obj(anno, windows)
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crop_and_save(anno, windows, window_objs, str(im_dir), str(lb_dir))
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def split_trainval(data_root, save_dir, crop_size=1024, gap=200, rates=(1.0,)):
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"""
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Split train and val set of DOTA.
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Notes:
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The directory structure assumed for the DOTA dataset:
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- data_root
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- images
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- train
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- val
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- labels
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- train
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- val
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and the output directory structure is:
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- save_dir
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- images
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- train
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- val
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- labels
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- train
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- val
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"""
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crop_sizes, gaps = [], []
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for r in rates:
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crop_sizes.append(int(crop_size / r))
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gaps.append(int(gap / r))
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for split in ["train", "val"]:
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split_images_and_labels(data_root, save_dir, split, crop_sizes, gaps)
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def split_test(data_root, save_dir, crop_size=1024, gap=200, rates=(1.0,)):
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"""
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Split test set of DOTA, labels are not included within this set.
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Notes:
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The directory structure assumed for the DOTA dataset:
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- data_root
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- images
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- test
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and the output directory structure is:
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- save_dir
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- images
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- test
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"""
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crop_sizes, gaps = [], []
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for r in rates:
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crop_sizes.append(int(crop_size / r))
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gaps.append(int(gap / r))
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save_dir = Path(save_dir) / "images" / "test"
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save_dir.mkdir(parents=True, exist_ok=True)
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im_dir = Path(data_root) / "images" / "test"
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assert im_dir.exists(), f"Can't find {im_dir}, please check your data root."
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im_files = glob(str(im_dir / "*"))
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for im_file in tqdm(im_files, total=len(im_files), desc="test"):
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w, h = exif_size(Image.open(im_file))
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windows = get_windows((h, w), crop_sizes=crop_sizes, gaps=gaps)
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im = cv2.imread(im_file)
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name = Path(im_file).stem
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for window in windows:
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x_start, y_start, x_stop, y_stop = window.tolist()
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new_name = f"{name}__{x_stop - x_start}__{x_start}___{y_start}"
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patch_im = im[y_start:y_stop, x_start:x_stop]
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cv2.imwrite(str(save_dir / f"{new_name}.jpg"), patch_im)
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if __name__ == "__main__":
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split_trainval(data_root="DOTAv2", save_dir="DOTAv2-split")
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split_test(data_root="DOTAv2", save_dir="DOTAv2-split")
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