yolov3.py

#!/usr/bin/env python3
# -*- coding:utf-8 -*-
# Copyright (c) Megvii, Inc. and its affiliates.

import os

import torch
import torch.nn as nn

from yolox.exp import Exp as MyExp


class Exp(MyExp):
    def __init__(self):
        super(Exp, self).__init__()
        self.depth = 1.0
        self.width = 1.0
        self.exp_name = os.path.split(os.path.realpath(__file__))[1].split(".")[0]

    def get_model(self, sublinear=False):
        def init_yolo(M):
            for m in M.modules():
                if isinstance(m, nn.BatchNorm2d):
                    m.eps = 1e-3
                    m.momentum = 0.03
        if "model" not in self.__dict__:
            from yolox.models import YOLOX, YOLOFPN, YOLOXHead
            backbone = YOLOFPN()
            head = YOLOXHead(self.num_classes, self.width, in_channels=[128, 256, 512], act="lrelu")
            self.model = YOLOX(backbone, head)
        self.model.apply(init_yolo)
        self.model.head.initialize_biases(1e-2)

        return self.model

    def get_data_loader(self, batch_size, is_distributed, no_aug=False):
        import torch.distributed as dist

        from yolox.data import (
            COCODataset,
            DataLoader,
            InfiniteSampler,
            MosaicDetection,
            TrainTransform,
            YoloBatchSampler
        )

        dataset = COCODataset(
                data_dir='data/COCO/',
                json_file=self.train_ann,
                img_size=self.input_size,
                preproc=TrainTransform(
                    rgb_means=(0.485, 0.456, 0.406),
                    std=(0.229, 0.224, 0.225),
                    max_labels=50
                ),
        )

        dataset = MosaicDetection(
            dataset,
            mosaic=not no_aug,
            img_size=self.input_size,
            preproc=TrainTransform(
                rgb_means=(0.485, 0.456, 0.406),
                std=(0.229, 0.224, 0.225),
                max_labels=120
            ),
            degrees=self.degrees,
            translate=self.translate,
            scale=self.scale,
            shear=self.shear,
            perspective=self.perspective,
        )

        self.dataset = dataset

        if is_distributed:
            batch_size = batch_size // dist.get_world_size()
            sampler = InfiniteSampler(len(self.dataset), seed=self.seed if self.seed else 0)
        else:
            sampler = torch.utils.data.RandomSampler(self.dataset)

        batch_sampler = YoloBatchSampler(
            sampler=sampler,
            batch_size=batch_size,
            drop_last=False,
            input_dimension=self.input_size,
            mosaic=not no_aug
        )

        dataloader_kwargs = {"num_workers": self.data_num_workers, "pin_memory": True}
        dataloader_kwargs["batch_sampler"] = batch_sampler
        train_loader = DataLoader(self.dataset, **dataloader_kwargs)

        return train_loader