In the Preview tab, you can see the 2D height map, that you have generated, to better understand how the terrain is being generated.

Black represents zero altitude, with the brightest, white areas being full altitude, controlled by the Gain value in the Operator tab.

The Preview tab in tfNoise.

Source

There are seven types of Source available for every Generator operator: Altitude, which is set as default, Slope, Curvature, Bumps, Dents, 2D Fields Mask and Shader Mask.

tfGrid also has the Control Grid option and tfTrace, the Object Mask option.

Filter operators all have eight types of Source available, as they each also have the Difference Map option.

In addition, there are some operator specific modes, for example, the Hydraulic Erosion filter has Erode Map and Deposit Map options.

The Source drop-down menu with seven source type options.

In this image, there are four Source types for the same terrain. From the left, Altitude, Slope, Fields Mask and Shader Mask, respectively.

Open Monitor

Opens the source preview in the Grid Monitor.

Note: The Grid Monitor can also be opened via a command in the TerraformFX menu.