Gaussian Filter smooths volume data by convoluting it with a 3D Gaussian function of user-specified width. This improves the ratio of signal to noise but reduces resolution.
There are several ways to start Gaussian Filter, a tool in the Volume Data category (including from the Volume Viewer Tools menu).
After the desired Gaussian width (equal to twice the standard deviation of the Gaussian distribution) has been entered, pressing Filter performs the convolution on the current set of data in Volume Viewer. The convolution creates a new volume data set and makes it the current set; the original data set is hidden. The new data set can be saved to a file with Volume Viewer.
The computation is fastest for data sizes that are powers of 2, and can be very slow when insufficient memory is available. Currently Gaussian filtering uses temporary memory four times the size of the input data (if in 32-bit floating point values) and produces a 32-bit floating point result.