bart
March 30th, 2007, 02:04
Motion blur has two areas in which it can be controlled. I now like to bring up the new Render Manager to be able to see both areas, the pass and mental ray tabs of render options.
Motion blur now has three pass settings for controlling where the key position/orientation of the object is considered to be for a given frame,
at the start of the blur
at the center of the blur
at the end of the blur
Most CG folk may like to choose the center, but as an old timer who thinks about time from a time code and film editing perspective, I like to use the start of the blur.
I have also done matchmoving using both approaches, the start of the blur, and the center of the blur. So often one must consider all the other things that must work together with the 3D animation. It may be that for some particular shot matchmoving to the end of the blur works best.
Now beyond positioning the blur in the pass options, the other controls may further adjust blur length, etc.
Shutter speed controls the amount of "open shutter" time. A typical movie camera will be open for about 144 degrees out of 360 degrees of full rotation. So this equates to a shutter speed of 144/360 or 0.4.
The controls in the pass options tab control the motion by choosing the appropriate motion transforms/vectors to give to mental ray.
Now the controls in the mental ray tab, shutter and shutter delay, can further refine the offset and open shutter time, where shutter is shutter close time in frame time, and shutter delay is shutter open time in frame time. However, it is best to avoid these in XSI, as the control over the motion transform/vectors in the pass options can do everything you need.
In addition, historically XSI translates motion information to mental ray in a reversed order, so that the shutter and shutter delay affect blur in the reverse direction from what one might expect.
Motion blur now has three pass settings for controlling where the key position/orientation of the object is considered to be for a given frame,
at the start of the blur
at the center of the blur
at the end of the blur
Most CG folk may like to choose the center, but as an old timer who thinks about time from a time code and film editing perspective, I like to use the start of the blur.
I have also done matchmoving using both approaches, the start of the blur, and the center of the blur. So often one must consider all the other things that must work together with the 3D animation. It may be that for some particular shot matchmoving to the end of the blur works best.
Now beyond positioning the blur in the pass options, the other controls may further adjust blur length, etc.
Shutter speed controls the amount of "open shutter" time. A typical movie camera will be open for about 144 degrees out of 360 degrees of full rotation. So this equates to a shutter speed of 144/360 or 0.4.
The controls in the pass options tab control the motion by choosing the appropriate motion transforms/vectors to give to mental ray.
Now the controls in the mental ray tab, shutter and shutter delay, can further refine the offset and open shutter time, where shutter is shutter close time in frame time, and shutter delay is shutter open time in frame time. However, it is best to avoid these in XSI, as the control over the motion transform/vectors in the pass options can do everything you need.
In addition, historically XSI translates motion information to mental ray in a reversed order, so that the shutter and shutter delay affect blur in the reverse direction from what one might expect.