transforms_3d.py

# modify from https://github.com/mit-han-lab/bevfusion
from typing import Any, Dict

import numpy as np
import torch
from mmcv.transforms import BaseTransform
from PIL import Image

from mmdet3d.registry import TRANSFORMS


@TRANSFORMS.register_module()
class ImageAug3D(BaseTransform):

    def __init__(self, final_dim, resize_lim, bot_pct_lim, rot_lim, rand_flip,
                 is_train):
        self.final_dim = final_dim
        self.resize_lim = resize_lim
        self.bot_pct_lim = bot_pct_lim
        self.rand_flip = rand_flip
        self.rot_lim = rot_lim
        self.is_train = is_train

    def sample_augmentation(self, results):
        H, W = results['ori_shape']
        fH, fW = self.final_dim
        if self.is_train:
            resize = np.random.uniform(*self.resize_lim)
            resize_dims = (int(W * resize), int(H * resize))
            newW, newH = resize_dims
            crop_h = int(
                (1 - np.random.uniform(*self.bot_pct_lim)) * newH) - fH
            crop_w = int(np.random.uniform(0, max(0, newW - fW)))
            crop = (crop_w, crop_h, crop_w + fW, crop_h + fH)
            flip = False
            if self.rand_flip and np.random.choice([0, 1]):
                flip = True
            rotate = np.random.uniform(*self.rot_lim)
        else:
            resize = np.mean(self.resize_lim)
            resize_dims = (int(W * resize), int(H * resize))
            newW, newH = resize_dims
            crop_h = int((1 - np.mean(self.bot_pct_lim)) * newH) - fH
            crop_w = int(max(0, newW - fW) / 2)
            crop = (crop_w, crop_h, crop_w + fW, crop_h + fH)
            flip = False
            rotate = 0
        return resize, resize_dims, crop, flip, rotate

    def img_transform(self, img, rotation, translation, resize, resize_dims,
                      crop, flip, rotate):
        # adjust image
        img = Image.fromarray(img.astype('uint8'), mode='RGB')
        img = img.resize(resize_dims)
        img = img.crop(crop)
        if flip:
            img = img.transpose(method=Image.FLIP_LEFT_RIGHT)
        img = img.rotate(rotate)

        # post-homography transformation
        rotation *= resize
        translation -= torch.Tensor(crop[:2])
        if flip:
            A = torch.Tensor([[-1, 0], [0, 1]])
            b = torch.Tensor([crop[2] - crop[0], 0])
            rotation = A.matmul(rotation)
            translation = A.matmul(translation) + b
        theta = rotate / 180 * np.pi
        A = torch.Tensor([
            [np.cos(theta), np.sin(theta)],
            [-np.sin(theta), np.cos(theta)],
        ])
        b = torch.Tensor([crop[2] - crop[0], crop[3] - crop[1]]) / 2
        b = A.matmul(-b) + b
        rotation = A.matmul(rotation)
        translation = A.matmul(translation) + b

        return img, rotation, translation

    def transform(self, data: Dict[str, Any]) -> Dict[str, Any]:
        imgs = data['img']
        new_imgs = []
        transforms = []
        for img in imgs:
            resize, resize_dims, crop, flip, rotate = self.sample_augmentation(
                data)
            post_rot = torch.eye(2)
            post_tran = torch.zeros(2)
            new_img, rotation, translation = self.img_transform(
                img,
                post_rot,
                post_tran,
                resize=resize,
                resize_dims=resize_dims,
                crop=crop,
                flip=flip,
                rotate=rotate,
            )
            transform = torch.eye(4)
            transform[:2, :2] = rotation
            transform[:2, 3] = translation
            new_imgs.append(np.array(new_img).astype(np.float32))
            transforms.append(transform.numpy())
        data['img'] = new_imgs
        # update the calibration matrices
        data['img_aug_matrix'] = transforms
        return data


@TRANSFORMS.register_module()
class GridMask(BaseTransform):

    def __init__(
        self,
        use_h,
        use_w,
        max_epoch,
        rotate=1,
        offset=False,
        ratio=0.5,
        mode=0,
        prob=1.0,
        fixed_prob=False,
    ):
        self.use_h = use_h
        self.use_w = use_w
        self.rotate = rotate
        self.offset = offset
        self.ratio = ratio
        self.mode = mode
        self.st_prob = prob
        self.prob = prob
        self.epoch = None
        self.max_epoch = max_epoch
        self.fixed_prob = fixed_prob

    def set_epoch(self, epoch):
        self.epoch = epoch
        if not self.fixed_prob:
            self.set_prob(self.epoch, self.max_epoch)

    def set_prob(self, epoch, max_epoch):
        self.prob = self.st_prob * self.epoch / self.max_epoch

    def transform(self, results):
        if np.random.rand() > self.prob:
            return results
        imgs = results['img']
        h = imgs[0].shape[0]
        w = imgs[0].shape[1]
        self.d1 = 2
        self.d2 = min(h, w)
        hh = int(1.5 * h)
        ww = int(1.5 * w)
        d = np.random.randint(self.d1, self.d2)
        if self.ratio == 1:
            self.length = np.random.randint(1, d)
        else:
            self.length = min(max(int(d * self.ratio + 0.5), 1), d - 1)
        mask = np.ones((hh, ww), np.float32)
        st_h = np.random.randint(d)
        st_w = np.random.randint(d)
        if self.use_h:
            for i in range(hh // d):
                s = d * i + st_h
                t = min(s + self.length, hh)
                mask[s:t, :] *= 0
        if self.use_w:
            for i in range(ww // d):
                s = d * i + st_w
                t = min(s + self.length, ww)
                mask[:, s:t] *= 0

        r = np.random.randint(self.rotate)
        mask = Image.fromarray(np.uint8(mask))
        mask = mask.rotate(r)
        mask = np.asarray(mask)
        mask = mask[(hh - h) // 2:(hh - h) // 2 + h,
                    (ww - w) // 2:(ww - w) // 2 + w]

        mask = mask.astype(np.float32)
        mask = mask[:, :, None]
        if self.mode == 1:
            mask = 1 - mask

        # mask = mask.expand_as(imgs[0])
        if self.offset:
            offset = torch.from_numpy(2 * (np.random.rand(h, w) - 0.5)).float()
            offset = (1 - mask) * offset
            imgs = [x * mask + offset for x in imgs]
        else:
            imgs = [x * mask for x in imgs]

        results.update(img=imgs)
        return results