The second point can be any point on the positive portion of the X axis. The first point will become the origin of the new co-ordinate system. The three points represent three positions in the new XY plane. The 3point option prompts you to pick 3 points in space which it uses to define the position of the new XY plane. You can also gain direct access to the options from the fly-out UCS buttons on the standard toolbar or from the UCS toolbar.įirst let's have a look at a practical example of defining a UCS using the 3point option. Note that the pull-down menu allows direct access to all of these options. Origin/ZAxis/3point/OBject/View/X/Y/Z/Prev/Restore/Save/Del/?/: When you start the UCS command from the keyboard or from the toolbar you are presented with lots of options on the command line: All of these options are available to you when you use the UCS command. Also, when you are working in a UCS the W disappears from the icon to indicate that you are no longer in the World Co-ordinate System.ĪutoCAD provides a number of ways to define a User Co-ordinate System. Is coplanar with the front vertical face of the box.Īs you can see from the two illustrations above, the UCS icon shifts its position to indicate the orientation of the current View with a User Co-ordinate System which Orientation of the UCS icon in an oblique you) must create a new co-ordinate system, in other words, you must define In fact AutoCAD takes this analogy and turns On the vertical face of a box you would need to move the XY plane in such a way that it lay coplanar (in the same plane) with the vertical face of the box.īy moving the XY plane you are by definition changing the co-ordinate system. Using only the World Co-ordinate System this would be impossible because circles (like many other AutoCAD entities) can only be drawn in the XY plane.ĪutoCAD gets round this problem by allowing you to move the XY plane into a different position. This method works very well for simple 3D objects, but say you wanted to draw a circle on one of the vertical faces of the box you have just drawn. To produce a 3D effect all you have to do is to change one of the 2D rectangles parameters i.e. Notice that to produce this 3D box you have only worked in 2D. For example to draw an open ended box you would simply draw a rectangle in plan and then use Change Properties to give it a thickness. This plane is known as the XY plane.Īs mentioned above, almost all drawing with AutoCAD happens in 2D. The 2D drawing plane that you see in plan when you first start AutoCAD can be thought of as the ground under your feet. You can think of the World Co-ordinate System as representing the real world.
The W stands for "World" and indicates that you are using the World Co-ordinate System. The third piece of information contained in the UCS icon is the letter W. Will appear as "0.0000" in the status bar and will not change as you move the cursor because you are only moving in the XY Plane. If you have just opened a new drawing the Z co-ordinate By implication the Z axis points straight out of the screen towards us. X and Y co-ordinates increase in the direction indicated by the UCS icon. As your cursor moves over the screen area you can see the change in X and Y co-ordinates by watching the co-ordinate statusĪrea at the bottom left of the screen ( X,Y,Z). These first two parts of the icon indicate the position and direction of the X and Y axes. Second, the icon contains a figure Y and an arrow head which points from bottom to top along the left hand side of the screen. First, the icon contains a figure X and an arrow which points from left to right along the bottom of the screen. The icon looks like the illustration on the right and shows 3 specific bits of information. In the bottom left hand corner of the drawing area is an icon, known as the UCS icon. When you first start up AutoCAD you are presented with a plan view of the drawing area. They decided upon has become known as UCS, User Co-ordinate Systems. When Autodesk, the makers ofĪutoCAD incorporated 3D into the program they needed some method for doing so without completely rewriting the software. Almost all the AutoCAD drawing and editĬommands can only work in 2D (the exceptions being commands like 3DPOLY and 3DFACE). If you just want to quickly find a description of the UCS options, click on the appropriate button on the QuickFind toolbar below.ĪutoCAD started life as a two-dimensional drafting program. Producing good 3D models and they can also help with 2D work. The correct use of UCSs with AutoCAD is the key to
#Differentiate between ucs and wcs in autocad how to#
This tutorial describes what UCSs are, why we need them and how to use them.