Offline Rendering to Image / Video

This notebook shows a images and videos / animations can be rendered.

from vape4d import render
from vape4d.utils import diverging_alpha
import numpy as np
from matplotlib import pyplot as plt
from PIL import Image

def volume(t,N=8):
    """Generate a 3D volume for a time step t

    Args:
        t (float): time
        N (int, optional): Number of points in each dimension. Defaults to 8.

    Returns:
        np.ndarray: 3D array of floats
    """
    x = np.linspace(-1,1,N)
    y = np.linspace(-1,1,N)
    z = np.linspace(-1,1,N)
    X,Y,Z = np.meshgrid(x,y,z)
    return np.sin(t*2*np.pi*(X+Y+Z))

Static Image

# the diverging_alpha function creates a colormap that is transparent at the ends
cmap = diverging_alpha(plt.get_cmap("magma"))

# volume of shape [T,W,H,D]
data = np.stack([volume(t,N=64) for t in np.linspace(0,1,32)])


img = render(
    data.astype(np.float32), # expects float32 
    cmap,
    0.9, # time step between (0,1)
    width=512,
    height=512,
    distance_scale=10,
    background=(0,0,0,0) # transparent background
)
Image.fromarray(img)

Video

import matplotlib.animation as animation
from IPython.display import HTML
fps = 24
video_duration = 3
n_frames = fps * video_duration
video = render(
    data, 
    cmap,
    np.linspace(0,1,n_frames), # time step between (0,1)
    width=512,
    height=512,
    distance_scale=10,
    background=(0,0,0,0) # transparent background
)

frames = [] # for storing the generated images
fig = plt.figure()
plt.axis('off')
for i in range(len(video)):
    frames.append([plt.imshow(video[i],animated=True)])

ani = animation.ArtistAnimation(fig, frames, interval=1000/fps, blit=True)
plt.close()
HTML(ani.to_jshtml())

Once Loop Reflect