Coordinate Systems

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When you're transforming objects numerically in the Object Attributes dialog, you can use one of two coordinate systems: Absolute Coordinates or Definition Coordinates.

Absolute Coordinates

Absolute Coordinates use the World Space axes as the reference for object transformations. When you enter transformation values using Absolute Coordinates, you're defining how the object is transformed along the World Space, or absolute, X, Y, and Z axes.

Absolute Coordinates use the World Space axes as reference, so you're repositioning the object along the absolute X, Y, and Z axes.

Definition Coordinates

Definition (Object Space) Coordinates define how an object is actually created. In object space, the origin of the object is located at X=0, Y=0, Z=0. All the other points in the object are defined by coordinates along the object's internal X, Y and Z axes.

Definition Coordinates define how an object is created. The origin is at 0, 0, 0, while all the other points that define the object's shape and size are coordinates along the X, Y and Z-axes within the object.

This coordinate system uses the object's internal axes as a reference for transformations. When you enter transformation values using this system, you change how the object is defined to include the position of its origin, its size, and orientation.

In Definition transformations, the origin point of the object always remains at Object Space 0, 0, 0. As you move or scale the object, it changes, moves or grows along its internal axes, but the origin remains at 0, 0, 0. This can cause some unpredictable results. For example, if you scale an object using Definition Coordinates, the origin point will no longer be in the exact center of the object. When you rotate the object, it won't rotate around its center.

Transforming using Definition Coordinates is not the same as using Object Space with one of the Transformation tools. When you choose Object Space for one of the transformation tools, transformations are performed using Object Space axes as a reference, but the final position, or size, is calculated using Absolute Coordinates. So in this case the object origin and all its points move along with the object.

When you use Definition Coordinates to transform an object, you're redefining how the object is created, so its origin does not change as the size and position change.

Relative Coordinates

Relative Coordinates use the World Space axes as reference for object transformations, but the values represent changes relative to the object's current position, or size. For example, if you enter a position change of 2 units, the object moves two units from its current position along one of the World Space axes

Relative Coordinates is the only coordinate system available in the 3D Transformation dialog.

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