Advanced Motion Blur

Here are examples of what you can do with temporal_filter_type, temporal_filter_width, and temporal_filter_exponent.

For some time, flame animations have been rendered by slowly changing xforms and parameters and iterating for a fraction of the total quality at each time step. The iterations are uniformly distributed across all of the temporal_samples specified in the <flame> tag. This results in images that look like the following sample (sheep 118163, flock 202, frame 10 of 80):

One alternative to the uniform distribution of points is to set the temporal_filter_type attribute to "gaussian". The iterations will appear clustered near the middle of the motion rather than uniformly spanning all of the temporal samples.

temporal_filter_type="gaussian":

We also now can expand the motion blur past -0.5/+0.5 time steps using the //temporal_filter_width// attribute.

temporal_filter_type="gaussian" temporal_filter_width="2":

To get directional motion rather than blurred motion, set temporal_filter_type to "exp", and use the temporal_filter_exponent attribute to control the speed and direction of the motion. temporal_filter_exponent defaults to 0.0, which is omnidirectional (for backwards compatibility). If temporal_filter_exponent is > 0, then later time steps are emphasized, and if < 0, earlier time steps are emphasized. Using the same flame:

temporal_filter_type="exp" temporal_filter_exponent="-2.0":