uniDEM supports numerous methods to fill voids that simulate terrain, or linearly fill as required.

#### Perimeter Void Fill

The Perimeter Void Fill samples all pixels non-void pixels adjacent to the edge of a void for a consistent elevation
and then to applies the sampled elevation to all of the void data.

The elevation can be sampled as a function of statistical measures around the perimeter of each void as follows:

- Percentile - order all adjacent pixels from lowest to highest and select the height from the percentile entered
- Mean/Standard Deviation - calculate the mean and standard deviation of all adjacent pixels and select the height to be
the mean + a multiple of the standard deviation.

Default shortcut: none

#### Kernel Void Fill

Kernel based fills can be performed on voids of a defined size.

Supported types are:

- Gaussian
- Boxcar
- Inverse Distance Weighted

Default shortcut: none

#### Smooth Curvature

Fill operation that fills small voids using the curvature of the void edge to provide propagate terrain in a natural way.

Default shortcut: none

#### Delta Surface

Delta Surface is a powerful set of void filling tools inspired by George Kroenung's(NGA) DSF tool.

Delta Surface can be used to fill a DEM with an alternate source, merge neighbouring DEMs in a seamless manner,
or bulk adjust sections of the Active DEM with using a copy of itself.

Default shortcut: none

#### Triangulation

Fills all selected voids with triangles connected to the edge of the void.
The triangle size can be modified to increase speed or reduce the visibility of in-filled triangles.

Default shortcut: none