Part 3: The Bearings - The Coordinate System

The Coordinate System

You should work with coordinates to accurately create and move objects with the drawing. In engineering design, objects are drawn at actual scale size [1= 1]. You can locate points from a fixed reference point within a drawing by entering coordinates as you draw or modify objects. There are two types of coordinate systems "2-D and 3-D". In 2-D drawings, you enter two-dimensional coordinates such as "x and y"; for 3-D drawing objects, you enter three-dimensional coordinates such as "x, y and z".

Cartesian Coordinates

Cartesian coordinates are based on a rectangular system of measurement.  The same principle is applied to enter 3D coordinates with the exception that you need to enter an additional Z coordinate.  Positive Z-coordinate values are used when you need to measure distances above the XY plan; negative values are used for the distances below the XY plane.  

Polar Coordinate System

Polar coordinates allow you to define a point by specifying the distance and the direction from a given point. This way of measurement is must useful in working with angles. To draw a line at an angle, you need to state how long a line you want to draw and specify the angle.

The Cartesian Coordinates System

The Cartesian Coordinates System is a rectangle system of measurement that enables you to locate points with the help of horizontal and vertical coordinates. The horizontal values, called X-coordinates, are measured along the X-axis. The vertical values, called Y-coordinates, are measured along the Y-axis. The intersection of the X- and Y-axis is called the origin point, which represents the 0,0 location of the coordinate system, where X=0 and Y=0. Positive X values are measured to the right and the Positive Y values are measured above the origin (0,0). The negative X and Y values are measured to the left and below the origin (0,0).


The coordinate system is a method of locating points in the drawing area. It enables you to locate points by specifying distances from a fixed reference point. You locate a point by giving its distance in the horizontal direction, vertical direction, measuring along an angle, etc.

(Note: The exact method of entering coordinates may vary from one program to another. For example, in AutoCAD, the coordinates can be entered directly in the command window with the keyboard.

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Part 3: The Bearings - The Coordinate System