AutoCAD Lesson coordinate system

2D Coordinates & 3D Coordinates
- Absolute Coordinates
- Relative Coordinates
- Relative Polar Coordinates

1. AUTOCAD
Lesson 2 : Coordinate
Systems
Lesson Objectives:
To understand various coordinate system used in
AutoCAD.

2. Two Dimensional (2D) Coordinate
Systems
In a two dimensional (2D) coordinate system, points are
defined on a 2D flat surface that represents a plane.
The coordinates of the point are located by measuring from
two perpendicular lines that represent the X (horizontal) and
Y (vertical) axes.
The intersection where the X and Y axes meet is called the
origin. In technical drawings, the X and Y axes represent a
2D area referred to as the “XY plane”

3. In the example below, the origin point’s value would be stated as
“zero comma zero”, or (0,0), which means the location of the origin is
zero units (0) on the X axis and zero units (0) on the Y axis.
A point, represented by a green dot, is located at coordinate 2,3. This
means that the point’s location is 2 units to the right of the origin on
the X axis and 3 units above the origin on the Y axis.

4. AutoCAD coordinates are based on the Cartesian Coordinate system.
Cartesian Coordinate System

5. Three Dimensional (3D) Coordinate
Systems
In a three dimensional (3D) coordinate system, a Z axis is
added to the X and Y axes.
Using this system, points can be located relative to the
origin along the X, Y and Z axes. The Z axis represents the
height of the point above or below the X,Y plane.
For example, a 3D coordinate might be defined with the
coordinates 1,1,1. This coordinate would lie one unit to the
right of the origin along the X axis, one unit from the origin
along the Y axis, and one unit above the X,Y plane.

7. TYPES OF COORDINATE
SYSTEMS
Absolute Coordinate System01
Relative Coordinate System02
Polar Coordinates03
In AutoCAD, the default origin is located at the lower left
corner of the graphics area of the screen. AutoCAD uses the
following coordinate systems to locate a point in XY plane.

8. Absolute Coordinate System
In the absolute coordinate system
the points are located with
respect to the origin (0,0).
For example, a point with
X = 4 and Y = 3
Is measured 4 units horizontally
(displacement along the X axis)
and 3 units vertically
(displacement along the Y axis)
from the origin.
In AutoCAD, the absolute
coordinates are specified by
entering X and Y coordinates,
separated by a comma.

9. STEPS
1.Command: LINE
2.Specify first point: 1,1
3.Specify next point: 4,1
4.Specify next point: 4,3
5.Specify next point: 1,3
6.Specify next point or
[Close/Undo]: 1,1
Absolute Coordinate System
DRAWING LINES USING ABSOLUTE COORDINATES

10. Relative Coordinate System
After first points entered, your
next points can be entered by
specifying the next coordinate
compare/relative from the first
points.
The relative coordinate started
with symbol “@” tell AutoCAD
it was a relative coordinates.
Using relative coordinate,
points entered by typing
@x,y[Enter]

11. STEPS
1.Command: LINE
2.Specify first point: 1,1
3.Specify 2nd point: @4,0
4.Specify 3rd point: @0,3
5.Specify 4th point: @-4,0
6.Specify Start point: @0,-3
or [Close/Undo]
Relative Coordinate System
DRAWING LINES USING ABSOLUTE COORDINATES

12. Relative Polar Coordinate
In the relative polar coordinate
system, a point can be located by
defining both the distance of the
pointfrom the current point and
the anglethat the line between
the two points makes with the
positive X axis.
The prompt sequence to draw a
line from a point at 1,1 to a
distance of 5 units from the point
(1,1), and at an angle of 30
degrees to the X axis is
STEPS
1.Command: LINE
2.Specify first point: 1,1
3.Specify next point: @5<30

13. TYPES OF COORDINATE SYSTEMS
Absolute Coordinate System01
Relative Coordinate System02
Relative Polar Coordinates03
Two Dimensional (2D) Coordinate SystemsA
Three Dimensional (3D) Coordinate SystemsB
SUMMARY

14. THANK
YOU