2D Motion Blur
Project files: 2dmotionblur.zip
The aim of this tutorial is to explain how to use Turtle's 2D motion blur. First we need a simple animated Maya scene.
The scene consists of a number of small, red spheres running around in a grey room.
Let's render the scene at a frame in the middle of the animation. The rendered image should look something like this:
Introduction
In Turtle's render globals, you find five parameters to control the blur:
Motion Blur Type, defines if the motion blur is to be 3D or a 2D approximation.
Camera Shutter Angle, that controls the time the camera shutter is open.
Blur length is a multiplier for the camera Shutter Angle, that allows us to achieve longer blurred trails without changing the global animation settings.
There is also four more options,Time Sample Density, Max Time Samples, Contrast Threshold, Enable Approximation. Those options are only available when using 3D Motion Blur, and will be disabled when choosing 2D Motion Blur.
Camera Shutter Angle & Blur Length
Enable 2D Motion Blur under Turtle's Render Globals, but don't change the default settings. Render the scene. You should have a scene like this:
Try change the Camera Shutter Angle to 30. Render again. The camera shutter shutter time has decreased and we see that the blurred trail is shorter.
Try experimenting with the Blur Length parameter. This allows you to have longer shutter times. If you increase the Blur Length, you are likely to see sampling artifacts due to the linear nature of the 2D motion blur.
Artifacts due to Linear approximation
The linearity of the 2D motion blur is clearly visible here. Be careful when using a large Blur Length on objects that not have a linear motion path.
Other artifacts to consider are that shadows will not be blurred if the shadow caster is moving, neither will reflected moving objects be blurred.