Rotate an image around its x-axis

Question

I need to rotate an image around its x-axis (or y-axis). I can easily create such an animation with avisynth, but now I need to implement that effect with Python's moviepy module. I can easily rotate an image with the following script but need some clues how to rotate it in 2D or 3D.

from moviepy.editor import *

clip = ImageClip('my_image.jpg')
rotated_clip = (clip.add_mask()
                .fx(vfx.resize, width=300, height=300)
                .fx(vfx.rotate, lambda t: 90*t, expand=False)
                .set_duration(5))
final_clip = CompositeVideoClip([rotated_clip.set_pos("center")], size=(800,800), bg_color=3*[255])
final_clip.write_videofile("test.mp4", fps=25, codec="libx264")

Here is the avisynth script that actually generated that example image. Please note, it does require "QUAD" plugin.

function stars(clip c, int r) {
    c.Overlay(x=rand(c.width),y=rand(c.height),BlankClip(c,width=1,height=1,color=$030301*rand(85)))
    (r==0)? last : stars(r-1)
    Trim(0,-1).Loop(c.Framecount, 0, 0)
}
width= 800
height=600
length=100000
Tcolor=$000040
Bcolor=$000018

StackVertical(BlankClip(length=length,width=2,height=1,color=TColor,pixel_type="RGB32"),BlankClip(length=length,width=2,height=1,color=BColor)).BilinearResize(width,2*height,src_top=0,src_height=2).Crop(0,height/2,0,-height/2).Stars(width*height/3072)

ImageSource("path_to_image.png", start=0, end=total_time, fps=300, pixel_type="RGB32")
#BlankClip(length=length,FPS=25,width=640,height=480,color=$000018,pixel_type="RGB32")

#ColorBars()
HALFCYCLE=10                        # Frames in 1 HALF rotation (spinning clip)
NSPIN   = 1                         # Number of HALF rotations in spinning clip
NSTILL  = 10                        # Frames in STILL clip
V       = 0.2                       # Tilt/Yaw
tim     = PI / HALFCYCLE

ScriptClip("""

    c=last
    t=tim*current_frame
    t1x= 0.5 -  0.5 * cos(t)        # BOTH Left
    t2x= 0.5 +  0.5 * cos(t)        # BOTH Right
    #
    t1y= 0.0 +  V * sin(t)          # ] both Top's opposite sign
    t2y= 0.0 -  V * sin(t)          # ] 
    t3y= 1.0 +  V * sin(t)          # [ both Bottoms opposite sign
    t4y= 1.0 -  V * sin(t)          # [
    ResetMask
    quad(t1x,t1y, t2x,t2y, t2x,t3y, t1x,t4y,  normal=true)
    #Overlay(c,last,mask=last.ShowAlpha())


""")

SPIN=Trim(0,-(NSPIN*HALFCYCLE +1))     # Spinning clip, + 1 to complete last spin
STILL=SPIN.Trim(SPIN.FrameCount-1,-1).Loop(NSTILL,0,0)
SPIN2=Trim((NSPIN%2 ==0)?0:HALFCYCLE,-(NSPIN*HALFCYCLE +1))
SPIN ++ STILL ++ SPIN2
Return Last

Answer 1

One way to do this is to use Vapory, another library by the author of MoviePy, which facilitates the operation of POV-Ray via Python. You can create a rectangle within a 3D scene and rotate it around whatever axis you like, saving frames into a MoviePy clip at intervals.

MoviePy + Vapory code

from moviepy.editor import concatenate, ImageClip, VideoClip
from vapory import *  # Yes, this is the library author's suggested usage.

img_path = './baseball.png'
img_clip = ImageClip(img_path)
W, H = img_clip.w, img_clip.h # Image width and height
AR = 1.0*W/H  # Aspect ratio used when scaling later

t_rev   = 2.0       # Time (in seconds) to complete one full revolution
t_half  = t_rev*0.5 # Time required for a half revolution
t_still = 0.8       # Time to hold the half rotated image still
frame_rate = 15 # Number of frames per second in the output

# Static POV-Ray objects
cam = Camera('location', [ 0,  0, -1],
             'look_at',  [ 0,  0,  0])
light = LightSource([0, 0, -1]) # Light at camera location
bg = Background('color', [0, 0, 0]) # Black background

def scene(t):
    """Returns the scene at time t (in seconds)."""
    s = Scene(camera = cam, objects = [light, bg])

    # Add POV-Ray box with image textured on it
    s = s.add_objects([
        Box(
            [0, 0, 0],
            [W, H, 0],
            Texture(
                Pigment(ImageMap('"{}"'.format(img_path), 'once')),
                Finish('ambient', 1.0)
            ),
            'translate', [-0.5, -0.5, 0], # Center box in field of view
            'scale', [AR, 1, 0], # Scale to given aspect ratio
            'rotate', [0, (360/t_rev)*t, 0], # Can change rotation axis here
        ),
    ])
    return s

def make_frame(t):
    return scene(t).render(width=W, height=H, antialiasing=0.1)
 
still_1 = VideoClip(make_frame).to_ImageClip(t=0).set_duration(t_still)
half_1  = VideoClip(make_frame).subclip(0, t_half)
still_2 = VideoClip(make_frame).to_ImageClip(t=t_half).set_duration(t_still)
half_2  = VideoClip(make_frame).subclip(t_half, t_rev)

final_clip = concatenate([still_1, half_1, still_2, half_2])
final_clip.write_videofile("./baseball_rot.mp4", fps=frame_rate, codec="libx264")
# Or: final_clip.write_gif("./baseball_rot.gif", fps=frame_rate)

Output GIF

Other thoughts

The main variables to adjust are img_path, t_rev (the time for a full 360 degree revolution), t_still, and frame_rate. For video encoding to work, you will likely need to crop and/or scale so the width and height are multiples of 8 pixels (not necessary for GIF output).

It's overkill to use a ray tracer for this problem, but that is the first approach that I got working. I wanted to represent the image as a 2D rectangle inside a 3D scene where I could simply specify an angle of rotation and the 3D library would handle the rest. It should be possible to solve this problem using a projective transform from scikit-image, as in this MoviePy example. Note specifically, the trapzWarp function near the middle of that code listing.