The infinite 2D grid in the 3D environment can be used to visually "ground" a project if you have multiple data sets or it can be useful for "quickly eyeballing" distances.
Accessing the grid
There are two ways to access the grid:
Click on the 2D data plane button located in the bottom right hand corner. A window will be launched which allows you to turn on/off the gridlines and to adjust the elevation* of the 2D data plane.
Tip: to quickly determine the elevation of a particular location, place a point markup at the point of interest and read off its z-coordinate.
2. If the grid is turned on, right-click anywhere in your project scene and select the 2D data plane item in the window that pops up (see below). This option is only available when the grid is turned on.
Understanding distances
When the grid is turned on, the length of the grid square sides is shown under the 2D button (see below).
*if you have chosen to display your units and measurements in the imperial system, the elevation of the 2D data plane will still appear in metres. This is because the underlying CRS of all projects are in the metric system.