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MahaB82A
MahaB82A
October 11, 2022
Question

Why is it blur?

  • October 11, 2022
  • 2 replies
  • 1155 views

Aeroplane is not blur when it hit the last frame otherwise it is blur. What is reason for that? video is attached

  

2 replies

R
Community Expert
Rick GerardCommunity Expert
Community Expert
October 11, 2022

Motion blur is calculated by shutter angle and shutter phase. Motion Picture cameras have rotary shutters. Imagine half of a disk with the center to the right of the frame. It spins, exposing the film when it is not moving, and then closes to give the pull-down claws a chance to move the film to the next frame. The standard shutter angle for a motion picture camera is 180º, giving an effective shutter speed of just almost exactly 1/50 of a second at 24 fps. This results in motion blur that looks natural to our human eyes when we watch a movie. A video camera with a shutter speed of about 1/50 of a second gives about the same pleasing motion blur. Many professional video cameras have the option to set the shutter angle or the shutter speed to control motion blur. 

The Composition Settings/Advanced tab allows you to adjust the shutter angle and shutter phase. The default is 180º shutter angle and a -90º shutter phase. This will give you motion blur starting from the center of the moving layer and moving toward the direction of movement on the first motion keyframe and half of the normal motion blur starting from the middle of the layer, moving away from the motion on the last one. This simulates the motion blur of a standard motion picture camera with the standard frame rate and will very closely match the motion blur you get when using the camera.

 

You can fiddle with the settings. If you have no motion blur on the last keyframe, then the Shutter Phase is set to a positive value. If the shutter phase is negative, the motion blur will be lagging behind the motion at the end, giving you a natural-looking end to the movement.

 

You can increase the amount of motion blur by adjusting the shutter angle, and you can adjust when the blur starts by adjusting the shutter phase. For almost all animations, the default 180º - 90º settings are best. If you need to change the look of the motion blur, use the Composition Settings/Advanced tab to make the changes. Zooming all the way in on the timeline so you can see individual frames will give you a visual representation of the amount of motion blur you are getting and when it happens.

 

I hope this helps. It's pretty easy to figure out if you started out in the business using film cameras with rotating shutters, but it can be a bit confusing to people that have never been exposed to the subject.

 

Maybe this screenshot will help.

To fix your problem, just go to the advanced tab and fiddle with the Shutter Phase and Angle until you get the blur you want on the last frame.  At full playback speed, the default settings will look the best for most of your work. 

 

 

    MahaB82A
    MahaB82AAuthor
    October 11, 2022

    If you observe a plane going along the sky you do not see blurring effect. Therefore blurring effect in the video is unnatural. Only I see blurring effect when certain machine parts run fast. 

    R
    Community Expert
    Rick GerardCommunity Expert
    Community Expert
    October 11, 2022

    The human eye interprets motion blur in anything that is moving quickly. If you follow the object, like a your plane flying across the sky, there is no motion blur, but if you are looking at the house across the street and you do not move your eyes, and a car drives down the street at about 20 MPH, you will perceive about the same motion blur that you would see if you shot the scene with a camera. If your eye changes to focus on the car and you follow it, then the house will have a little motion blur. Here's another weird thing about the human eye. It's impossible to do a smooth pan across a scene. You can follow motion, but if you try to stand on the rim of the Grand Canyon and pan across the vista before you, you will end up cutting from one angle to another. Try panning around your kitchen with your eyes. It's almost impossible to not cut from the refrigerator to the stove, to the sink, to the table. 

     

    High shutter speeds produce a video that can have jerky and annoying movement. Almost all motion faster than 2 or 3 pixels per second looks better with motion blur. The faster the movement, the more you need motion blur to make your animation work. Sometimes you even have to enhance the motion blur to make a move more effective.

     

    There is also a phenomenon that is called Judder. That's where the speed of movement in the frame gets out of sync with the frame rate, and the movement appears to jump or be uneven. This is most visible with rolling credits. It's the same kind of stroboscopic effect that causes stage coach wheels to look like they are moving backward or propellers to appear to change direction.

     

    There are many research papers on how the human eye perceives movement. The problem with designing motion graphics and animation is that the eye will tend to follow the prominent movement in a frame, just like it follows the predominant movement in your surroundings. You have to pay attention to speed, color, luminance, and composition to tell your story effectively. You cannot make any judgment calls on the effectiveness of any anamated scene by stepping through the animation one frame at a time. You have to look at it playing back in real-time. Twelve frames per second is about the minimum frame rate required to get smooth animation. All of those Warner Brothers cartoons were really only 12 fps. They photographed each cell twice and projected the film at 24 fps. They look pretty good because they followed the twelve principles of animation established by Frank Thomas and Ollie Johnson in their amazing book "The Illusion of Life." Anyone that is trying to tell a story by moving things around on a screen should study this book. I've had a copy since it came out in 1981. I re-read it about once a year.  

     

      Warren Heaton
      Community Expert
      Warren HeatonCommunity Expert
      Community Expert
      October 11, 2022

      This is actually pretty striaght forward.

      As Motion Blur is calculated based on the motion of the Layer, there is no blur at the tail of your animation because the Layer has stopped moving.

       

      If you set the Work Area End at your current last keyframe (0:00:04:00) and then continue the keyframing past that with at least one more keyframe at 0:00:04:15 you'll still have blur when the animation ends.  You would want the keyframe that you place at 0:00:04:15 to be about the same location for the plane as the one at 0:00:02:15.

      Also, if you're going for a four second animation loop, you actauly want the Work Area End to be one frame before 0:00:04:00.  So, press Page Up or click Previus Frame in the Preview panel while at 0:00:04:00 to go the prior frame and then press N to set the end of the Work Area.

       

      So, in summary, right now you have nine keyframes.  You need a tenth keyframe while your animation still ends at the nineth keyframe.

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