A set of interrelated tools in the program gives you precise control of the scale, placement, and movement of objects in your scene. These are especially important tools for those who build precise models in real-world units of measurement.
The tools for precision are grouped as follows:
Units: Define different measurement systems. Besides the generic unit, you have your choice of feet and inches in both decimals and fractions. Metric units range from millimeters to kilometers. You can also define other units.
Grids: Include the home grid and special grid objects. Both types of grid can act as construction planes. The software constructs objects using the orientation and position of the active grid. While the home grid is fixed in world space, you can rotate grid objects and place them anywhere in a scene, and align them to other objects and surfaces. You can also give each grid object its own spacing, and display any grid as a dedicated viewport.
Object alignment: Matches an object with the position, orientation, or normal of another object, or to a point in space.
Object snaps: Ensure precise placement when creating and rearranging objects. Keyboard shortcuts let you change object snaps as you work. You can also set snaps to find grid lines and intersections. An angle snap sets the increment for rotation, and a percent snap sets the increment for scaling.
Helpers: Provide useful assistance, as the name implies. These are specialized tools in the same category as grid objects. A Tape object measures distances in current units, and a Protractor object measure angles. A Point object marks a particular spot in 3D space.
The tools themselves establish a general order of use and interaction, although you can always change settings as needed without following this sequence.
Choose a measuring unit. The default is generic units, sufficient for many purposes.
Set grid spacing (the size of the smallest square), based on the measuring unit. The home grid and grid objects can have their own spacing, separate from the grid spacing.
Move and align grid objects to a useful orientation.
Set or vary snap settings as needed in your work.
Use other helper objects like Point and Tape as part of the precision process.
As you work, you can change your settings (including the measuring unit) without losing any precision.