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# Ultralytics YOLO 🚀, AGPL-3.0 license
import json
from collections import defaultdict
from pathlib import Path
import cv2
import numpy as np
from tqdm import tqdm
from ultralytics.utils.checks import check_requirements
from ultralytics.utils.files import make_dirs
def coco91_to_coco80_class():
"""Converts 91-index COCO class IDs to 80-index COCO class IDs.
Returns:
(list): A list of 91 class IDs where the index represents the 80-index class ID and the value is the
corresponding 91-index class ID.
"""
return [
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, None, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, None, 24, 25, None,
None, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, None, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
51, 52, 53, 54, 55, 56, 57, 58, 59, None, 60, None, None, 61, None, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72,
None, 73, 74, 75, 76, 77, 78, 79, None]
def convert_coco(labels_dir='../coco/annotations/', use_segments=False, use_keypoints=False, cls91to80=True):
"""Converts COCO dataset annotations to a format suitable for training YOLOv5 models.
Args:
labels_dir (str, optional): Path to directory containing COCO dataset annotation files.
use_segments (bool, optional): Whether to include segmentation masks in the output.
use_keypoints (bool, optional): Whether to include keypoint annotations in the output.
cls91to80 (bool, optional): Whether to map 91 COCO class IDs to the corresponding 80 COCO class IDs.
Raises:
FileNotFoundError: If the labels_dir path does not exist.
Example Usage:
convert_coco(labels_dir='../coco/annotations/', use_segments=True, use_keypoints=True, cls91to80=True)
Output:
Generates output files in the specified output directory.
"""
save_dir = make_dirs('yolo_labels') # output directory
coco80 = coco91_to_coco80_class()
# Import json
for json_file in sorted(Path(labels_dir).resolve().glob('*.json')):
fn = Path(save_dir) / 'labels' / json_file.stem.replace('instances_', '') # folder name
fn.mkdir(parents=True, exist_ok=True)
with open(json_file) as f:
data = json.load(f)
# Create image dict
images = {f'{x["id"]:d}': x for x in data['images']}
# Create image-annotations dict
imgToAnns = defaultdict(list)
for ann in data['annotations']:
imgToAnns[ann['image_id']].append(ann)
# Write labels file
for img_id, anns in tqdm(imgToAnns.items(), desc=f'Annotations {json_file}'):
img = images[f'{img_id:d}']
h, w, f = img['height'], img['width'], img['file_name']
bboxes = []
segments = []
keypoints = []
for ann in anns:
if ann['iscrowd']:
continue
# The COCO box format is [top left x, top left y, width, height]
box = np.array(ann['bbox'], dtype=np.float64)
box[:2] += box[2:] / 2 # xy top-left corner to center
box[[0, 2]] /= w # normalize x
box[[1, 3]] /= h # normalize y
if box[2] <= 0 or box[3] <= 0: # if w <= 0 and h <= 0
continue
cls = coco80[ann['category_id'] - 1] if cls91to80 else ann['category_id'] - 1 # class
box = [cls] + box.tolist()
if box not in bboxes:
bboxes.append(box)
if use_segments and ann.get('segmentation') is not None:
if len(ann['segmentation']) == 0:
segments.append([])
continue
if isinstance(ann['segmentation'], dict):
ann['segmentation'] = rle2polygon(ann['segmentation'])
if len(ann['segmentation']) > 1:
s = merge_multi_segment(ann['segmentation'])
s = (np.concatenate(s, axis=0) / np.array([w, h])).reshape(-1).tolist()
else:
s = [j for i in ann['segmentation'] for j in i] # all segments concatenated
s = (np.array(s).reshape(-1, 2) / np.array([w, h])).reshape(-1).tolist()
s = [cls] + s
if s not in segments:
segments.append(s)
if use_keypoints and ann.get('keypoints') is not None:
k = (np.array(ann['keypoints']).reshape(-1, 3) / np.array([w, h, 1])).reshape(-1).tolist()
k = box + k
keypoints.append(k)
# Write
with open((fn / f).with_suffix('.txt'), 'a') as file:
for i in range(len(bboxes)):
if use_keypoints:
line = *(keypoints[i]), # cls, box, keypoints
else:
line = *(segments[i]
if use_segments and len(segments[i]) > 0 else bboxes[i]), # cls, box or segments
file.write(('%g ' * len(line)).rstrip() % line + '\n')
def convert_dota_to_yolo_obb(dota_root_path: str):
"""
Converts DOTA dataset annotations to YOLO OBB (Oriented Bounding Box) format.
The function processes images in the 'train' and 'val' folders of the DOTA dataset. For each image, it reads the
associated label from the original labels directory and writes new labels in YOLO OBB format to a new directory.
Args:
dota_root_path (str): The root directory path of the DOTA dataset.
Example:
```python
from ultralytics.data.converter import convert_dota_to_yolo_obb
convert_dota_to_yolo_obb('path/to/DOTA')
```
Notes:
The directory structure assumed for the DOTA dataset:
- DOTA
- images
- train
- val
- labels
- train_original
- val_original
After the function execution, the new labels will be saved in:
- DOTA
- labels
- train
- val
"""
dota_root_path = Path(dota_root_path)
# Class names to indices mapping
class_mapping = {
'plane': 0,
'ship': 1,
'storage-tank': 2,
'baseball-diamond': 3,
'tennis-court': 4,
'basketball-court': 5,
'ground-track-field': 6,
'harbor': 7,
'bridge': 8,
'large-vehicle': 9,
'small-vehicle': 10,
'helicopter': 11,
'roundabout': 12,
'soccer ball-field': 13,
'swimming-pool': 14,
'container-crane': 15,
'airport': 16,
'helipad': 17}
def convert_label(image_name, image_width, image_height, orig_label_dir, save_dir):
orig_label_path = orig_label_dir / f'{image_name}.txt'
save_path = save_dir / f'{image_name}.txt'
with orig_label_path.open('r') as f, save_path.open('w') as g:
lines = f.readlines()
for line in lines:
parts = line.strip().split()
if len(parts) < 9:
continue
class_name = parts[8]
class_idx = class_mapping[class_name]
coords = [float(p) for p in parts[:8]]
normalized_coords = [
coords[i] / image_width if i % 2 == 0 else coords[i] / image_height for i in range(8)]
formatted_coords = ['{:.6g}'.format(coord) for coord in normalized_coords]
g.write(f"{class_idx} {' '.join(formatted_coords)}\n")
for phase in ['train', 'val']:
image_dir = dota_root_path / 'images' / phase
orig_label_dir = dota_root_path / 'labels' / f'{phase}_original'
save_dir = dota_root_path / 'labels' / phase
save_dir.mkdir(parents=True, exist_ok=True)
image_paths = list(image_dir.iterdir())
for image_path in tqdm(image_paths, desc=f'Processing {phase} images'):
if image_path.suffix != '.png':
continue
image_name_without_ext = image_path.stem
img = cv2.imread(str(image_path))
h, w = img.shape[:2]
convert_label(image_name_without_ext, w, h, orig_label_dir, save_dir)
def rle2polygon(segmentation):
"""
Convert Run-Length Encoding (RLE) mask to polygon coordinates.
Args:
segmentation (dict, list): RLE mask representation of the object segmentation.
Returns:
(list): A list of lists representing the polygon coordinates for each contour.
Note:
Requires the 'pycocotools' package to be installed.
"""
check_requirements('pycocotools')
from pycocotools import mask
m = mask.decode(segmentation)
m[m > 0] = 255
contours, _ = cv2.findContours(m, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_TC89_KCOS)
polygons = []
for contour in contours:
epsilon = 0.001 * cv2.arcLength(contour, True)
contour_approx = cv2.approxPolyDP(contour, epsilon, True)
polygon = contour_approx.flatten().tolist()
polygons.append(polygon)
return polygons
def min_index(arr1, arr2):
"""
Find a pair of indexes with the shortest distance between two arrays of 2D points.
Args:
arr1 (np.array): A NumPy array of shape (N, 2) representing N 2D points.
arr2 (np.array): A NumPy array of shape (M, 2) representing M 2D points.
Returns:
(tuple): A tuple containing the indexes of the points with the shortest distance in arr1 and arr2 respectively.
"""
dis = ((arr1[:, None, :] - arr2[None, :, :]) ** 2).sum(-1)
return np.unravel_index(np.argmin(dis, axis=None), dis.shape)
def merge_multi_segment(segments):
"""
Merge multiple segments into one list by connecting the coordinates with the minimum distance between each segment.
This function connects these coordinates with a thin line to merge all segments into one.
Args:
segments (List[List]): Original segmentations in COCO's JSON file.
Each element is a list of coordinates, like [segmentation1, segmentation2,...].
Returns:
s (List[np.ndarray]): A list of connected segments represented as NumPy arrays.
"""
s = []
segments = [np.array(i).reshape(-1, 2) for i in segments]
idx_list = [[] for _ in range(len(segments))]
# record the indexes with min distance between each segment
for i in range(1, len(segments)):
idx1, idx2 = min_index(segments[i - 1], segments[i])
idx_list[i - 1].append(idx1)
idx_list[i].append(idx2)
# use two round to connect all the segments
for k in range(2):
# forward connection
if k == 0:
for i, idx in enumerate(idx_list):
# middle segments have two indexes
# reverse the index of middle segments
if len(idx) == 2 and idx[0] > idx[1]:
idx = idx[::-1]
segments[i] = segments[i][::-1, :]
segments[i] = np.roll(segments[i], -idx[0], axis=0)
segments[i] = np.concatenate([segments[i], segments[i][:1]])
# deal with the first segment and the last one
if i in [0, len(idx_list) - 1]:
s.append(segments[i])
else:
idx = [0, idx[1] - idx[0]]
s.append(segments[i][idx[0]:idx[1] + 1])
else:
for i in range(len(idx_list) - 1, -1, -1):
if i not in [0, len(idx_list) - 1]:
idx = idx_list[i]
nidx = abs(idx[1] - idx[0])
s.append(segments[i][nidx:])
return s