Grid
The grid is an array of lines on the construction plane in the viewport that extends from the origin.
Part of Rhinoceros , Rhinoceros for OSX
Part Type Interface
Screenshot Construction lines.jpg

Introduction to the Grid

The grid is a finite array of lines lying on the construction plane . It is often helpful to show the grid when starting to build a model because it offers a reference for the scale of the model. Snapping to the grid is useful to create precise geometric forms. The center of the grid indicates where the origin point (0,0) of the model is, the location of which is important to know when exporting the model.

When a new Rhino file is opened, the spacing and size of the default grid depends on the size and units of the model. (It is helpful to change the units to something realistic for the model because it makes modeling easier.) The grid's spacing, size, style, and visibility are options that can be edited. Use the Grid command or click Tools->Options->Grid (under Document Properties).

Grid Options

Enter units based on the unit system of the model. For example, if the unit system is feet, a major line interval can be specified as 5'.

Spacing

Major line interval
The units at which major grid lines are spaced.
Minor line spacing
Minor lines are the lines between the major lines. Sets the spacing of these lines.

Size

Extents
Defines the extents of the grid about the origin. The maximum size of the grid is 10,000 units.

Visibility

Show grid
Toggles the visibility of the grid. If the grid is too dense, navigating the model may become slow, so hiding the grid from view would help speed things up.
Show grid axes
Toggles the visibility of the green and red x- and y-axes.
Show world axis
Toggles the visibility of the icon in the bottom left corner of a viewport that indicates the axes of the viewport.
Apply grid changes to
Choose if the grid options are applied to all viewports or just the active viewport.
Grid colors
In the Rhino Options window (accessible by using the "Options" command), the Color options under Appearance can be changed for the major and minor grid lines, as well as the axis lines.

Grid Snap

Snap spacing
When grid snap is on, the cursor snaps to the next unit increment. Specify the unit of spacing.
"Snap" command
Use this command to toggle grid snap on and off. This can also be done by clicking on Snap in the bottom of the Rhino window.