pc_utils.py

import numpy as np
import torch

# source: https://github.com/charlesq34/pointnet2/blob/74bb67f3702e8aec55a7b8765dd728b18456030c/utils/provider.py#L187-L198
def jitter_point_cloud(batch_data, sigma=0.01, clip=0.05):
    """ Randomly jitter points. jittering is per point.
        Input:
          BxNx3 array, original batch of point clouds
        Return:
          BxNx3 array, jittered batch of point clouds
    """
    B, N, C = batch_data.shape
    assert(clip > 0)
    jittered_data = np.clip(sigma * np.random.randn(B, N, C), -1*clip, clip)
    jittered_data += batch_data
    return jittered_data

# source: https://github.com/charlesq34/pointnet2/blob/74bb67f3702e8aec55a7b8765dd728b18456030c/utils/provider.py#L32-L50
def rotate_point_cloud(batch_data):
    """ Randomly rotate the point clouds to augument the dataset
        rotation is per shape based along up direction
        Input:
          BxNx3 array, original batch of point clouds
        Return:
          BxNx3 array, rotated batch of point clouds
    """
    rotated_data = np.zeros(batch_data.shape, dtype=np.float32)
    for k in range(batch_data.shape[0]):
        rotation_angle = np.random.uniform() * 2 * np.pi
        cosval = np.cos(rotation_angle)
        sinval = np.sin(rotation_angle)
        rotation_matrix = np.array([[cosval, 0, sinval],
                                    [0, 1, 0],
                                    [-sinval, 0, cosval]])
        shape_pc = batch_data[k, ...]
        rotated_data[k, ...] = np.dot(shape_pc.reshape((-1, 3)), rotation_matrix)
    return rotated_data

# source: https://github.com/WangYueFt/dgcnn/blob/master/pytorch/data.py
def translate_pointcloud(pointcloud):
    xyz1 = np.random.uniform(low=2./3., high=3./2., size=[3])
    xyz2 = np.random.uniform(low=-0.2, high=0.2, size=[3])

    translated_pointcloud = np.add(np.multiply(pointcloud, xyz1), xyz2).astype('float32')
    return translated_pointcloud

# based on https://github.com/Yochengliu/Relation-Shape-CNN/blob/master/data/data_utils.py#L81
class PointcloudScaleAndTranslate(object):
    def __init__(self, scale_low=2. / 3., scale_high=3. / 2., translate_range=0.2, no_z_aug=False):
        """
        :param scale_low:
        :param scale_high:
        :param translate_range:
        :param no_z: no translation and scaling along the z axis
        """
        self.scale_low = scale_low
        self.scale_high = scale_high
        self.translate_range = translate_range
        self.no_z_aug = no_z_aug

    def __call__(self, pc):
        bsize = pc.size()[0]
        for i in range(bsize):
            xyz1 = np.random.uniform(low=self.scale_low, high=self.scale_high, size=[3])
            xyz2 = np.random.uniform(low=-self.translate_range, high=self.translate_range, size=[3])
            if self.no_z_aug:
                xyz1[2] = 1.0
                xyz2[2] = 0.0
            pc[i, :, 0:3] = torch.mul(pc[i, :, 0:3], torch.from_numpy(xyz1).float().cuda()) + torch.from_numpy(xyz2).float().cuda()

        return pc