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Coordinate System

This lesson will explain coordinate systems which are crucial to understanding AutoCAD® and how to create drawings and objects. Below you will see a coordinate system with several points labeled. Our AutoCAD coordinate system video tutorial may also be helpful to learn about the coordinate system.

Notice the two thick lines on the coordinate system. The thick horizontal line is called the x-axis. The thick vertical line is called the y-axis. The intersection of these two lines is a point called the origin. The origin is the beginning reference point of the coordinate system. Any other point on the coordinate system is relative to the origin. The thin lines mark evenly spaced distances from the origin. The actual distance does not usually matter, as long as it is evenly spaced because a coordinate system is just a representation of something else. In AutoCAD®, a coordinate system is usually a representation of space. Another example of a coordinate system could be time.

You may want to draw a rectangle that is 2 units long and 1 unit high. You could start at the origin and move to the right 2 units, and then up 1 unit. This would be a rectangle of the proportion that you wanted. The lower left corner of this rectangle would be the origin. The upper right corner of this rectangle would be 2 units on the x-axis, and 1 unit on the y-axis. You would refer to these as the x-coordinate or just x, and the y-coordinate or just the y. You would write these in a comma notation, first the x, then the y and sometimes you would put them in parentheses. So the coordinates for the upper right corner of our box would be (2,1). The coordinates for the lower left corner of our box would be (0,0), which are the coordinates of the origin. You should note that these coordinates are marks of points, not spaces or blocks, just a point of an intersection of a specified x and a specified y.

You may specify points to the left of the x-axis or below the y-axis by specifying negative points. You can see some negative points labeled at -2,-1 and at -3,2 and at 1,-3. Coordinates do not have to be whole numbers. They may be fractions or decimals. In AutoCAD®, a grid is not used, but you are shown a rather open space known as the drawing area. A symbol called the UCS labels the origin and has arrows to specify the x-axis and the y-axis. Below, you will see a screenshot of AutoCAD® with lines drawn on top of the UCS symbol to further emphasize the x-axis and the y-axis which usually remain invisible.

AutoCAD UCS

Now you will be able to draw basic shapes with coordinates such as lines, rectangles, >circles, and even some hatching patterns for those shapes.