💡💡💡本文摘要:基于YOLOv8的航空遥感飞机小目标检测,阐述了整个数据制作和训练可视化过程
1.YOLOv8介绍
Ultralytics YOLOv8是Ultralytics公司开发的YOLO目标检测和图像分割模型的最新版本。YOLOv8是一种尖端的、最先进的(SOTA)模型,它建立在先前YOLO成功基础上,并引入了新功能和改进,以进一步提升性能和灵活性。它可以在大型数据集上进行训练,并且能够在各种硬件平台上运行,从CPU到GPU。
具体改进如下:
-
Backbone:使用的依旧是CSP的思想,不过YOLOv5中的C3模块被替换成了C2f模块,实现了进一步的轻量化,同时YOLOv8依旧使用了YOLOv5等架构中使用的SPPF模块;
-
PAN-FPN:毫无疑问YOLOv8依旧使用了PAN的思想,不过通过对比YOLOv5与YOLOv8的结构图可以看到,YOLOv8将YOLOv5中PAN-FPN上采样阶段中的卷积结构删除了,同时也将C3模块替换为了C2f模块;
-
Decoupled-Head:是不是嗅到了不一样的味道?是的,YOLOv8走向了Decoupled-Head;
-
Anchor-Free:YOLOv8抛弃了以往的Anchor-Base,使用了Anchor-Free的思想;
-
损失函数:YOLOv8使用VFL Loss作为分类损失,使用DFL Loss+CIOU Loss作为分类损失;
-
样本匹配:YOLOv8抛弃了以往的IOU匹配或者单边比例的分配方式,而是使用了Task-Aligned Assigner匹配方式
框架图提供见链接:Brief summary of YOLOv8 model structure · Issue #189 · ultralytics/ultralytics · GitHub
2.航空遥感飞机小目标介绍
aircraft总共包含446张图片,按照7:2:1划分了training val test,标签名aircraft
2.1 split_train_val.py
# coding:utf-8
import os
import random
import argparse
parser = argparse.ArgumentParser()
#xml文件的地址,根据自己的数据进行修改 xml一般存放在Annotations下
parser.add_argument('--xml_path', default='Annotations', type=str, help='input xml label path')
#数据集的划分,地址选择自己数据下的ImageSets/Main
parser.add_argument('--txt_path', default='ImageSets/Main', type=str, help='output txt label path')
opt = parser.parse_args()
trainval_percent = 0.9
train_percent = 0.7
xmlfilepath = opt.xml_path
txtsavepath = opt.txt_path
total_xml = os.listdir(xmlfilepath)
if not os.path.exists(txtsavepath):
os.makedirs(txtsavepath)
num = len(total_xml)
list_index = range(num)
tv = int(num * trainval_percent)
tr = int(tv * train_percent)
trainval = random.sample(list_index, tv)
train = random.sample(trainval, tr)
file_trainval = open(txtsavepath + '/trainval.txt', 'w')
file_test = open(txtsavepath + '/test.txt', 'w')
file_train = open(txtsavepath + '/train.txt', 'w')
file_val = open(txtsavepath + '/val.txt', 'w')
for i in list_index:
name = total_xml[i][:-4] + '\n'
if i in trainval:
file_trainval.write(name)
if i in train:
file_train.write(name)
else:
file_val.write(name)
else:
file_test.write(name)
file_trainval.close()
file_train.close()
file_val.close()
file_test.close()
2.2 voc_label.py生成适合YOLOv8训练的txt
# -*- coding: utf-8 -*-
import xml.etree.ElementTree as ET
import os
from os import getcwd
sets = ['train', 'val', 'test']
classes = ["aircraft"] # 改成自己的类别
abs_path = os.getcwd()
print(abs_path)
def convert(size, box):
dw = 1. / (size[0])
dh = 1. / (size[1])
x = (box[0] + box[1]) / 2.0 - 1
y = (box[2] + box[3]) / 2.0 - 1
w = box[1] - box[0]
h = box[3] - box[2]
x = x * dw
w = w * dw
y = y * dh
h = h * dh
return x, y, w, h
def convert_annotation(image_id):
in_file = open('Annotations/%s.xml' % (image_id), encoding='UTF-8')
out_file = open('labels/%s.txt' % (image_id), 'w')
tree = ET.parse(in_file)
root = tree.getroot()
size = root.find('size')
w = int(size.find('width').text)
h = int(size.find('height').text)
for obj in root.iter('object'):
difficult = obj.find('difficult').text
#difficult = obj.find('Difficult').text
cls = obj.find('name').text
if cls not in classes or int(difficult) == 1:
continue
cls_id = classes.index(cls)
xmlbox = obj.find('bndbox')
b = (float(xmlbox.find('xmin').text), float(xmlbox.find('xmax').text), float(xmlbox.find('ymin').text),
float(xmlbox.find('ymax').text))
b1, b2, b3, b4 = b
# 标注越界修正
if b2 > w:
b2 = w
if b4 > h:
b4 = h
b = (b1, b2, b3, b4)
bb = convert((w, h), b)
out_file.write(str(cls_id) + " " + " ".join([str(a) for a in bb]) + '\n')
wd = getcwd()
for image_set in sets:
if not os.path.exists('labels/'):
os.makedirs('labels/')
image_ids = open('ImageSets/Main/%s.txt' % (image_set)).read().strip().split()
list_file = open('%s.txt' % (image_set), 'w')
for image_id in image_ids:
list_file.write(abs_path + '/images/%s.jpg\n' % (image_id))
convert_annotation(image_id)
list_file.close()
3.如何训练YOLOv8
3.1 配置aircraft.yaml
ps:建议填写绝对路径
path: ./data/aircraft # dataset root dir
train: train.txt # train images (relative to 'path') 118287 images
val: val.txt # val images (relative to 'path') 5000 images
# number of classes
nc: 1
# class names
names:
0: aircraft
3.2 如何训练
from ultralytics import YOLO
if __name__ == '__main__':
model = YOLO('ultralytics/cfg/models/v8/yolov8.yaml')
#model.load('yolov8n.pt') # loading pretrain weights
model.train(data='data/aircraft/aircraft.yaml',
cache=False,
imgsz=640,
epochs=200,
batch=16,
close_mosaic=10,
workers=0,
device='0',
optimizer='SGD', # using SGD
project='runs/train',
name='exp',
)
3.3 训练可视化结果
F1_curve.png:F1分数与置信度(x轴)之间的关系。F1分数是分类的一个衡量标准,是精确率和召回率的调和平均函数,介于0,1之间。越大越好。
TP:真实为真,预测为真;
FN:真实为真,预测为假;
FP:真实为假,预测为真;
TN:真实为假,预测为假;
精确率(precision)=TP/(TP+FP)
召回率(Recall)=TP/(TP+FN)
F1=2*(精确率*召回率)/(精确率+召回率)
PR_curve.png :PR曲线中的P代表的是precision(精准率),R代表的是recall(召回率),其代表的是精准率与召回率的关系。
预测结果:
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