Page 253 - Kitab3DsMax

Chapter 7: Transforming Objects, Pivoting, Aligning, and Snapping

l Reference Coordinate System: Defines the coordinate system about which the transformations
take place.
l Transform Center settings: The Pivot Point Center, the Selection Center, and the Transform
Coordinate Center. These settings specify the center about which the transformations take place.
l Axis Constraint settings: Allow the transformation to happen using only one axis or plane.
These buttons are on the Axis Constraints toolbar.

Understanding reference coordinate systems
Max supports several reference coordinate systems based on the UCS, and knowing which reference coordi-
nate system you are working with as you transform an object is important. Using the wrong reference
coordinate system can produce unexpected transformations.
Within the viewports, the UCS coordinates are displayed as a set of coordinates in the lower-left corner of
the viewport, and the transform gizmo is oriented with respect to the reference coordinate system.
To understand the concept of reference coordinate systems, imagine that you’re visiting the Grand Canyon
and are standing precariously on the edge of a lookout. To nervous onlookers calling the park rangers, the
description of your position varies from viewpoint to viewpoint. A person standing by you would say you
are next to him. A person on the other side of the canyon would say that you’re across from her. A person
at the floor of the canyon would say you’re above him. And a person in an airplane would describe you as
being on the east side of the canyon. Each person has a different viewpoint of you (the object), even though
you have not moved.
Max recognizes the following reference coordinate systems:
l View Coordinate System: A reference coordinate system based on the viewports; X points right,
Y points up, and Z points out of the screen (toward you). The views are fixed, making this per-
haps the most intuitive coordinate system to work with.
l Screen Coordinate System: Identical to the View Coordinate System, except the active viewport
determines the coordinate system axes, whereas the inactive viewports show the axes as defined
by the active viewport.
l World Coordinate System: Specifies X pointing to the right, Z pointing up, and Y pointing into
the screen (away from you). The coordinate axes remain fixed regardless of any transformations
applied to an object. For Max, this system matches the UCS.
l Parent Coordinate System: Uses the reference coordinate system applied to a linked object’s parent
and maintains consistency between hierarchical transformations. If an object doesn’t have a parent,
then the world is its parent and the system works the same as the World Coordinate System.
l Local Coordinate System: Sets the coordinate system based on the selected object. The axes are
located at the pivot point for the object. You can reorient and move the pivot point using the
Pivot button in the Hierarchy panel.
l Gimbal Coordinate System: Provides interactive feedback for objects using the Euler XYZ con-
troller. If the object doesn’t use the Euler XYZ controller, then this coordinate system works just
like the World Coordinate System.
l Grid Coordinate System: Uses the coordinate system for the active grid.
l Working Coordinate System: Lets you transform the selected object about the scene’s Working
Pivot as defined in the Hierarchy panel.
l Pick Coordinate System: Lets you select an object about which to transform. The Coordinate
System list keeps the last four picked objects as coordinate system options.
All transforms occur relative to the current reference coordinate system as selected in the Referenced
Coordinate System drop-down list found on the main toolbar.
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