If we work with the definition of 3Dimensional Space with the boundaries that define our WORKSPACE or SCENE, then the simplest way to do this is to imagine that we are working inside a large cube. We can imagine that this cube as our world or environment. Objects that exist within the cube one visible, those that fall outside are invisible.
The main point of reference in this world is called the World Origin. This origin is usually located in the center of this Space. But, it can also be placed or repositioned elsewhere depending on the modeling needs and straights.
The ORIGIN is a point of reference usually located in the center of the three dimensional space. It can also be located elsewhere in 3D Space. a 3D Space has width, height and depth dimensions each represented by the three axis in the cartesian coordinate system. Rene Descartes-the founder of Cartesian Coordinate System, formalized the idea of using three axes labelled X,Y and Z to represent the dimensions in three dimensional Space. The coordinate system he devised is commonly referred to as the Cartesian or Rectangular coordinate system. Each axis in the system can be divided into many units of measurements. In principle these units of measurements and scales of dimension. On each axis the values to one side of the origin are positive and the values on the other side are negative. Any World or global Coordinate System is usually useful for placing or moving objects in the world or in relation to each other. World Coordinates are absolute values that are relative to the origin of the world. These coordinates do not depend on any specific object in the world and are applied to all objects in the world in the world indistinctly.
a A POINT can be defined by its XYZ Position. b A LINE can be defined by the XYZ location of its two endpoints. c A PLANAR SURFACE can be defined by the position of its bounding lines.
Transformation: Geometric Transformations can be performed on single objects or on entire environments. Transformation that are applied to the objects using the environment’s axes and/or origin are called Global Transformations. When transformations are applied to a single objects or a limited selection of objects- using the objects own axes and origin, they are called Local Transformations. CONCENTRATED TRANSFORMATION is the name sometimes given to a series of global transformations applied in sequence.
Translation: Translation is the simplest of all geometric transformations. This operation is used to move an object or group of objects in a linear way to a new location in 3D Space. Translation is the simplest, and easiest to control, of all geometric transformations. Translation can occur along one axis or along several axes at the same time.
Rotation : Rotation is the geometric transformation used to move an element or group of elements around a specific center and axis. The amount of rotation is usually specified in terms of an angle of rotation (measured in degrees) and a direction of rotation. Rotations can be used to present the different sides of an object to the camera lens (directed towards the object).
Let us think about HIERARCHY. Depending on whether the rotation is global or local. Objects can be rotated around their “parent” in a hierarchy of objects. When rotating an object around its own center it is possible with many programs to reposition that center. Consequently, the center of rotation of an object may not always be placed in the geometric center of the object.