utils.py

from PIL import Image, ImageDraw
from torch.utils.data import RandomSampler
from io import BytesIO
import imageio.v2 as imageio
import numpy as np

from torchvision import transforms
from torchvision.utils import flow_to_image
import cv2
import torch
import os

def process_points(points, frames):

    if len(points) >= frames:

        frames_interval = np.linspace(0, len(points) - 1, frames, dtype=int)
        points = [points[i] for i in frames_interval]
        return points

    else:
        insert_num = frames - len(points)
        insert_num_dict = {}
        interval = len(points) - 1
        n = insert_num // interval
        for i in range(interval):
            insert_num_dict[i] = n

        m = insert_num % interval
        if m > 0:
            frames_interval = np.linspace(0, len(points)-1, m, dtype=int)
            if frames_interval[-1] > 0:
                frames_interval[-1] -= 1
            for i in range(interval):
                if i in frames_interval:
                    insert_num_dict[i] += 1

        res = []
        for i in range(interval):
            insert_points = []
            x0, y0 = points[i]
            x1, y1 = points[i + 1]

            delta_x = x1 - x0
            delta_y = y1 - y0

            for j in range(insert_num_dict[i]):
                x = x0 + (j + 1) / (insert_num_dict[i] + 1) * delta_x
                y = y0 + (j + 1) / (insert_num_dict[i] + 1) * delta_y
                insert_points.append([int(x), int(y)])

            res += points[i : i + 1] + insert_points
        res += points[-1:]
        
        return res


def get_flow(points, optical_flow, video_len):
    for i in range(video_len - 1):
        p = points[i]
        p1 = points[i + 1]
        optical_flow[i + 1, p[1], p[0], 0] = p1[0] - p[0]
        optical_flow[i + 1, p[1], p[0], 1] = p1[1] - p[1]

    return optical_flow


def sigma_matrix2(sig_x, sig_y, theta):
    """Calculate the rotated sigma matrix (two dimensional matrix).
    Args:
        sig_x (float):
        sig_y (float):
        theta (float): Radian measurement.
    Returns:
        ndarray: Rotated sigma matrix.
    """
    d_matrix = np.array([[sig_x**2, 0], [0, sig_y**2]])
    u_matrix = np.array([[np.cos(theta), -np.sin(theta)], [np.sin(theta), np.cos(theta)]])
    return np.dot(u_matrix, np.dot(d_matrix, u_matrix.T))


def mesh_grid(kernel_size):
    """Generate the mesh grid, centering at zero.
    Args:
        kernel_size (int):
    Returns:
        xy (ndarray): with the shape (kernel_size, kernel_size, 2)
        xx (ndarray): with the shape (kernel_size, kernel_size)
        yy (ndarray): with the shape (kernel_size, kernel_size)
    """
    ax = np.arange(-kernel_size // 2 + 1.0, kernel_size // 2 + 1.0)
    xx, yy = np.meshgrid(ax, ax)
    xy = np.hstack(
        (
            xx.reshape((kernel_size * kernel_size, 1)),
            yy.reshape(kernel_size * kernel_size, 1),
        )
    ).reshape(kernel_size, kernel_size, 2)
    return xy, xx, yy


def pdf2(sigma_matrix, grid):
    """Calculate PDF of the bivariate Gaussian distribution.
    Args:
        sigma_matrix (ndarray): with the shape (2, 2)
        grid (ndarray): generated by :func:`mesh_grid`,
            with the shape (K, K, 2), K is the kernel size.
    Returns:
        kernel (ndarrray): un-normalized kernel.
    """
    inverse_sigma = np.linalg.inv(sigma_matrix)
    kernel = np.exp(-0.5 * np.sum(np.dot(grid, inverse_sigma) * grid, 2))
    return kernel


def bivariate_Gaussian(kernel_size, sig_x, sig_y, theta, grid=None, isotropic=True):
    """Generate a bivariate isotropic or anisotropic Gaussian kernel.
    In the isotropic mode, only `sig_x` is used. `sig_y` and `theta` is ignored.
    Args:
        kernel_size (int):
        sig_x (float):
        sig_y (float):
        theta (float): Radian measurement.
        grid (ndarray, optional): generated by :func:`mesh_grid`,
            with the shape (K, K, 2), K is the kernel size. Default: None
        isotropic (bool):
    Returns:
        kernel (ndarray): normalized kernel.
    """
    if grid is None:
        grid, _, _ = mesh_grid(kernel_size)
    if isotropic:
        sigma_matrix = np.array([[sig_x**2, 0], [0, sig_x**2]])
    else:
        sigma_matrix = sigma_matrix2(sig_x, sig_y, theta)
    kernel = pdf2(sigma_matrix, grid)
    kernel = kernel / np.sum(kernel)
    return kernel

def read_points(file, video_len=16, reverse=False):
    with open(file, "r") as f:
        lines = f.readlines()
    points = []
    for line in lines:
        x, y = line.strip().split(",")
        points.append((int(x), int(y)))
    if reverse:
        points = points[::-1]

    if len(points) > video_len:
        skip = len(points) // video_len
        points = points[::skip]
    points = points[:video_len]

    return points

def process_traj(point_path, num_frames, video_size, device="cpu"):
    
    processed_points = []
    points = np.load(point_path)

    points = [tuple(x) for x in points.tolist()]
    h, w = video_size
    points = process_points(points, num_frames)
    xy_range = [640, 480]
    points = [[int(w * x / xy_range[0]), int(h * y / xy_range[1])] for x, y in points]
    points_resized = [] 
    for point in points:
        if point[0] >= xy_range[0]:
            point[0] = xy_range[0] - 1
        elif point[0] < 0:
            point[0] = 0
        elif point[1] >= xy_range[1]:
            point[1] = xy_range[1] - 1
        elif point[1] < 0:
            point[1] = 0
        points_resized.append(point)
    processed_points.append(points_resized)

    return processed_points

def process_traj_v2(point_path, num_frames, video_size, device="cpu"):
    optical_flow = np.zeros((num_frames, video_size[0], video_size[1], 2), dtype=np.float32)
    processed_points = []
    
    points = np.load(point_path)
    points = [tuple(x) for x in points.tolist()]
    h, w = video_size
    points = process_points(points, num_frames)
    xy_range = [640, 480]
    points = [[int(w * x / xy_range[0]), int(h * y / xy_range[1])] for x, y in points]
    points_resized = [] 
    for point in points:
        if point[0] >= xy_range[0]:
            point[0] = xy_range[0] - 1
        elif point[0] < 0:
            point[0] = 0
        elif point[1] >= xy_range[1]:
            point[1] = xy_range[1] - 1
        elif point[1] < 0:
            point[1] = 0
        points_resized.append(point)
    optical_flow = get_flow(points_resized, optical_flow, video_len=num_frames)
    processed_points.append(points_resized)
    
    size = 99
    sigma = 10
    blur_kernel = bivariate_Gaussian(size, sigma, sigma, 0, grid=None, isotropic=True)
    blur_kernel = blur_kernel / blur_kernel[size // 2, size // 2]
    
    assert len(optical_flow) == num_frames
    for i in range(1, num_frames):
        optical_flow[i] = cv2.filter2D(optical_flow[i], -1, blur_kernel)
    optical_flow = torch.tensor(optical_flow).to(device)

    return optical_flow, processed_points

def draw_circle(rgb, coord, radius, color=(255, 0, 0), visible=True, color_alpha=None):
    # Create a draw object
    draw = ImageDraw.Draw(rgb)
    # Calculate the bounding box of the circle
    left_up_point = (coord[0] - radius, coord[1] - radius)
    right_down_point = (coord[0] + radius, coord[1] + radius)
    # Draw the circle
    color = tuple(list(color) + [color_alpha if color_alpha is not None else 255])
    draw.ellipse(
        [left_up_point, right_down_point],
        fill=tuple(color) if visible else None,
        outline=tuple(color),
    )
    return rgb

def save_images2video(images, video_name, fps):
    format = "mp4"
    codec = "libx264" 
    ffmpeg_params = ["-crf", str(12)]
    pixelformat = "yuv420p" 
    video_stream = BytesIO()

    with imageio.get_writer(
        video_stream,
        fps=fps,
        format=format,
        codec=codec,
        ffmpeg_params=ffmpeg_params,
        pixelformat=pixelformat,
    ) as writer:
        for idx in range(len(images)):
            writer.append_data(images[idx])
    
    video_data = video_stream.getvalue()
    output_path = os.path.join(video_name + ".mp4")
    with open(output_path, "wb") as f:
        f.write(video_data)

def sample_flowlatents(latents, flow_latents, mask, points, diameter, transit_start, transit_end):

    points = points[:,::4,:]
    radius = diameter // 2
    channels = latents.shape[1]

    for channel in range(channels):
        latent_value = latents[:, channel, :].unsqueeze(2)[mask>0.].mean()
        for frame in range(transit_start, transit_end):
            if frame > 0:
                flow_latents[0,:,frame,:,:] = flow_latents[0,:,frame-1,:,:]
            centroid_x, centroid_y = points[0,frame]
            centroid_x, centroid_y = int(centroid_x), int(centroid_y)
            for i in range(centroid_y - radius, centroid_y + radius + 1):
                for j in range(centroid_x - radius, centroid_x + radius + 1):
                    if 0 <= i < flow_latents.shape[-2] and 0 <= j < flow_latents.shape[-1]: 
                        if (i - centroid_y) ** 2 + (j - centroid_x) ** 2 <= radius ** 2:
                            flow_latents[0,channel,frame,i,j] = latent_value + 1e-4

    return flow_latents