# 3D COORDINATE SYSTEM BASICS

3D models are stored using a 3D coordinate system. This page describes some of the more common elements of a coordinate system that you will need to be familiar with when modeling.

## Coordinates

Every point of a 3D model is mapped to a location in space measured along X, Y and Z. When taken together, {X,Y,Z} is called a coordinate. Wings 3D uses the Cartesian coordinate system.

## Axes XYZ

Looking at the Wings 3D workspace, you can see the red, blue, and green lines that represent the X,Y, and Z axes.

In Wings 3D, Y is up and down, X is side to side, and Z is front to back. These three axes are commonly used to define the active axis for moving, scaling, or rotating a model. Often in Wings 3D they will be referred to as Standard axes.

Note: Other modelers may swap the Y and Z axis, so when importing a model into Wings 3D it may appear to be the wrong way around.

## Points

A point is any location in 3D space. Points can be used as references, such as the center around which a model will be rotated. A point may be defined by the intersection of two vectors. Points can also be used to define the location of a plane.

## Vectors

A vector is defined by two points. Adding the coordinates of two points results in a vector coordinate including its magnitude.

A vector is generally necessary to establish a direction or axis depending on the context in which the vector is to be used. A vector is often used to define a direction for movement or an axis of rotation.

## Normals

An un-normalised vector denotes not just direction but also magnitude. Normalised vectors have a magnitude of 1.0, hence the meaning of normalisation.

## Planes

A plane is defined by a minimum of three unique points in space. These points make a triangle, which is the minimum requirement for defining a surface. Once we have these points, they can be added together to determine the plane vector. A plane’s location can be determined by finding the center or average of its defining points. However, if a plane’s vector is normalised, it represents a surface located anywhere in space. A normalised plane will often be used in conjunction with a point to place the plane.

To picture a plane vector, think of a table. The surface of the table represents a plane along which things can move in two directions. The plane vector as represented as a coordinate is actually a vector point straight up or perpendicular to the table’s surface. If we normalise this vector, then we can relocate the surface of the table to any parallel plane in the room. But once the table in rotated, the plane has changed. All parallel planes are represented by the same plane normal.

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