Autocad is a program dedicated in most cases to the creation of plans in two dimensions, but since the element that we are representing will always be in reality a three-dimensional object, it is very interesting to know the possibilities that the program offers us to build three-dimensional structures. Specialize with an AutoCAD Course!
The advantages of drawing in 3D in Autocad
Autocad offers us numerous drawing tools for create 3d objects and allows you to manipulate them in various ways. As we will see, modeling in Autocad is quite simple and we can generate a three-dimensional model that helps us visualize the project we are carrying out, or even that we can later export to other programs, for example for generating images.
The two-dimensional technical drawing is made in several views: plan, elevation, section, etc. and eventually some isometric view of the element can also be drawn. This system may have some errors, since not all the views are drawn simultaneously and errors in dimensions or position of some elements may be incurred. Although it is true that these errors occur, they occur much less since working with assisted drawing programs such as Autocad.
By creating the objects in three dimensions, we will be drawing them as they exist in reality and by not having to carry out several views, we minimize the margin of error because the changes that we apply to the model will always be reflected in all possible views.
Let us then know the basic tools to create a 3D structure in Autocad and the considerations to take into account to work in three dimensions.
Tools to work in 3D with Autocad
1. Control of the SCP (Personal Coordinate System)
The Personal Coordinate System (UCS) is a mobile coordinate system, and it is the option that Autocad gives us to change and rotate the coordinates of the drawing. By default, when we draw in two dimensions the coordinates are positive X to the right and Y positive to the top. We see this indicated by the pointer that appears in the lower left corner of the drawing area. To work in three dimensions, it is essential to be able to move and rotate the SCP. The coordinate system must be oriented to simplify the work when we are drawing in a plane that is not the universal X,Y base plane of the drawing. We will always keep in mind the orientation of our coordinate system since it will influence how objects move, rotate or are symmetries.
2. Views
The drawing area in Autocad is always oriented in plan view. To be able to work in three dimensions we need to see the drawing in parallel perspective. For this, the simplest is to use the view browser that appears in the upper right corner of the drawing area. This square indicates the orientation of the drawing, by default it indicates “Top” which means that we are in a plan view. If we move the cursor over the square, different parts light up in blue. To have a perspective view we must do click in a corner when lit, for example the lower left corner. The drawing area will automatically rotate, and it will be oriented in an isometric view. Notice that the pointer now consists of three axes with three different colors (red X, green Y, blue Z). Therefore now we have a new axis, the Z, which precisely defines the third dimension of the objects, which until now we did not have.
To navigate different views, we can go clicking on the different faces and corners of the square (which will now be a cube) and the view will change.
3. Creating a 3D prism
As a practical example we are going to create the simplest structure we can find: a slab (or ceiling) supported by four pillars. To create 3D objects in Autocad, we can start from a 2D base drawing, for example a rectangle, and make an extrusion, or directly generate the object in 3D. To do this, we need to have the tab active 3D tools. Within this menu we find the section Modeling. selecting “Square Textured Prism” we will be able to create a solid square or rectangular prism in 3D. We specify a point of origin (for example 0.0) and we will see that the base of the prism will always be in the XY plane while the height is specified in the direction of the Z axis. Once the dimensions have been introduced (for example, 5x5m and 0.30m high) we will have our roof in 3D.
4. Creating cylinders in 3D
Continuing in the same menu of «Modeling”, we can also create cylinders and we are going to use them to generate round pillars that support our roof. If we select Cylinder, also asks us for a point of origin, which in this case will be the center of the circle, we give it a coordinate (0.50,0.50) and then the radius or diameter that we want. The base of the cylinder will also be contained in a plane parallel to the work plane. Next it will ask us for a height, in this case it could be 3 meters, and we will already have a pillar. As we have said before, we need four pillars, so we either create them by entering the origin coordinates each time or we take advantage of the one we just drew to copy it where it touches.
5. Other 3D geometries in Autocad
in the menu of “Modeling”you will find many other 3D shapes that are created immediately by clicks of the mouse or entering the dimensions and coordinates. These are basically cones, spheres, pyramids, wedges, and toroids. With these shapes you can create almost any element in three dimensions. I encourage you to play for a while with them and discover the creative possibilities they offer!
6. Extrude 2D objects
This is another option to create a 3D surface or solid in Autocad. To generate a solid it will be necessary to have a closed object in two dimensions, for example a rectangle, a circle, etc. If what we extrude is a line or an open object, we will be generating a 3D surface. Once we have the object in two dimensions, we must execute the order “Extrusion”, select the object, and specify an extrusion height. Within this order we also have the possibility of defining an extrusion trajectory, for example if we were interested in generating an inclined pillar or an element that has a circular trajectory.
7. Visual styles in Autocad
Once we have generated our geometry, we will surely like to see it with a solid appearance. By default, Autocad shows us the objects in 3D with a style called “2D Wireframe”. In this style, we see the edges of the objects but we do not perceive them as solid elements. To work on the construction of the model, this is the best visual style since we can see perfectly where the vertices of the geometry are.
8. Change the visual style in Autocad
To change the style, we go to the tab “Visualize – Visual Styles”, and in the drop-down menu all those available in Autocad appear. You can go selecting each one of the styles and you will see how the visualization of the drawing changes: some have shadows, others make the edges disappear, etc. In this way we visualize our structure as it would look in reality.
9. 3D orbit
Before we have explained the change of views, but there is a much more versatile tool that is the 3D orbit. If we type “3do” on the command line and run it, we can rotate the view of our drawing freely in all directions. It is as if the object were inside a glass sphere that we can turn in our hands to where we want and see what it contains from different sides and orientations. You have to keep the cursor pressed and drag it in the direction you want.
10. Helps in the drawing area
Autocad has several parameters that will help us better understand 3D space and the objects in it. We can select and configure them in the lower toolbar of the drawing area. We can choose, for example, if we display the reference grid of the drawing (Grid), which will be useful to quickly see the orientation of the screen. There are many customization parameters that will make our work much easier.
In this post we have learned the basics of creating and manipulating 3D objects in Autocad.
Do you know any more advanced tool for working in three dimensions?