AutoCAD for 3D Modeling and Visualization
About three quarters of the world’s population are visual learners. This fact highlights the importance of quality visuals when communicating ideas. Clear images can be more accurately interpreted and lead to project success. Our ability to communicate in the AEC industry currently depends on the right software and modeling tools and how to get the most out of them. Better options for visualization have been exponentially improved due to advances in reality capture, GPU/CPU capacity, and rendering quality. There are many tools available for 3D modeling and visualization but some of the best tools are just within reach—that is, they are available in recent versions of AutoCAD®. Tools for working with point clouds, solid modeling, and internal renderings within AutoCAD have been forgotten in the shuffle, but still provide value due to their availability. Let's uncover what they can do.
Working with Point Clouds
As sensors get cheaper, the number of construction projects using laser scanners increases, especially when dealing with renovation work. These sensors are capable of collecting millions of points with millimetric accuracy, representing existing conditions in a scene. AutoCAD has your back if you want to visualize and interact with point clouds.
Under the Insert tab is the Point Cloud tools panel (see Figure 1). The first tool launches Autodesk® ReCap™, which is used to index, create, or edit point cloud project files. The second icon allows you to attach ReCap files (.rcp or .rcs only). If your point clouds are saved in a different file format, ReCap can convert those for you from the most generic content (.txt, .las, .laz) to the most specific laser scanning brands (Faro, Leica, Topcon, Riegl, DotProduct, and more).
Figure 1: Inserting the point cloud file
Once the file is inserted, there is another set of tools you can use to interact with your point cloud (see Figure 2). Even with Autodesk’s improvements to develop better tools and faster rendering of point clouds, these files are usually going to be large datasets that could create performance issues. In this case, your best friend could be the toolbar where you can control information related to Display/Visualization and Cropping. For example, the Level of Detail determines the number of 3D points shown on the screen. This is a huge help when you notice your computing performance starting to decline. The other handy tool that could save the day is Cropping. If you know you only need to partially visualize or model from part of the point cloud, you could save a ton of time by just turning off the points that are not going to be needed.
Figure 2: The point cloud toolbar
On the modeling aspect of point clouds, there are also commands to extract edges, corners, or centerlines of cylinders based on groups of points (see Figure 3). This is a big time saver to find and model wall edges, openings, or pipes. This is part of the effort of creating smarter point clouds. There’s huge interest in algorithms for point cloud segmentation in the research community, and there’s plenty of room for improvement.
Figure 3: Extracting geometry from point clouds
Adding Context to Visualization
Creating a mixture of content from different source types can enrich our models and make the process more flexible depending on the desired outcome. AutoCAD has features that provide more options while creating models such as interacting with 3D solids, 3D surfaces, and 3D meshes (see Figure 4). Some of these elements are more efficient to work with and others require more computing power; however, they complement each other, providing a variety of modeling features for the task at hand.
Figure 4: 3D element formats: solid, surface, and mesh (Source: knowledge.autodesk.com)
Combining reality capture with native AutoCAD elements, we are able to create models that give us more detailed information about the ideas we want to communicate. Figure 5 shows a point cloud in the middle of masses representing structures in a small area of an urban neighborhood.
The 3D solids help to give the context of the surroundings to plan and make better assumptions on this and similar projects.
Figure 5: Modeling 3d solids to create context
Recently, UAVs (drones) have been used more widely for commercial purposes. This increase in usage yields higher quality data that can be used to share with other stakeholders. Figure 6 shows building masses created from tracing building footprints and converted into solids using extrusion tools. Notice that the underlying image is a processed orthomosaic whose planimetry (i.e., not skewed) is accurate, compared to raw aerial images taken directly from a camera.
Figure 6: Building footprint tracing
Realistic Visualization
So far, we have covered visualization and modeling from a conceptual point of view. However, there is a point in the design process when we want to get realistic output. AutoCAD provides a library of realistic materials to enrich your renderings (see Figure 7). If the project requires custom textures, they can be incorporated as well. However, if the files are opened on a different computer, you will lose bitmaps if they're not transferred.
Figure 7: Realistic render
As a rule of thumb, initial renderings should be processed in low quality using a setting in the Render Presets Manager (see Figure 8) so that time is not wasted during tuning of minor details (i.e., lights, materials, and camera position.
Figure 8: Render Presets Manager
Now you can share your projects using A360 (Figure 9) and be able to reach a larger audience that doesn't use AutoCAD, just a web browser. It is possible to create multiple predefined views or the user can orbit the model. On the negative side, there are some issues with the conversion of materials, as we see on the cylinder below. In addition to that, custom textures will not show in the A360 viewer.
Figure 9: A360 viewer
In conclusion, if we want to encourage the use of a richer form of communication without jumping through endless software hoops, AutoCAD’s wealth of 3D tools is the answer. Or just add this to your repertoire of tools to improve the visualization of your output. We want to stress the different options that may be available. For instance, if you do not have access to a laser scanner, there are cheaper solutions by using drones and photogrammetry. And if you do not have a rendering machine, you could also rent a powerful virtual machine online to render in the background while you keep producing. In this day and age, there’s no excuse for not impressing your clients with powerful and contextualized output.
Xavier Loayza started using CAD software during high school. These drafting skills boosted him to collaborate very early in the AEC world to later pursue a path to civil engineering in Ecuador. After gaining experience over the years in transportation, geotechnical engineering, and surveying, Xavier got interested in UAVs (drones) for mapping, construction monitoring, and urban planning as a time- and cost-effective tool, leading him to establish a service company. In 2015, after this entrepreneurial project, Xavier joined a Construction Management graduate program at the University of Houston. Currently, he is collaborating with Axoscape, a BIM consulting company. He is always eager to learn and share.
