What Are Point Clouds?
Chances are you might be thinking of a bonus round for an addictive iPhone game when you hear the term “point cloud”. In fact, it’s a digital resource that can revolutionize your next renovation, repair or upfit project.
I had the opportunity to teach full time at Appalachian State University during the 2013-2014 school year and taught basic and advanced BIM techniques. It’s safe to say I feel pretty comfortable in the 3D modeling world, but I even avoided the point cloud button. I was intimidated and had closed myself off to a whole new way of documenting existing buildings. Below is an introduction to working with point clouds:
What are Point Clouds?
As it relates to architecture, a point cloud is a digital file consisting of a set of data points in a coordinate system. It’s a digital record of objects, such as walls, floors, ceilings, lights, -all surfaces, really- as billions of tiny points. The size of the file depends on the amount of data. Most of the files are often 2GB or more.
Who Can Use Point Cloud Data?
- Building Owners
- Facility Managers
How Is a Point Cloud Created?
Point clouds are created through 3D laser scanning. Think of it as a combination between a camera and an office copy/scanner. For interior and exterior building scans, the scanner is a camera device on a level tripod. If a building is being scanned, a team will set up several locations and create several scans. The scanner rotates in all directions and gathers surrounding information. Then, the scan consultants use software to precisely line up all of the different scan files. All of the individual scans then create the point cloud file. I like to think of it like a Dymaxion Map. It helps me understand how the different scans are stitched together to create a 3D point cloud file.
source: Buckminster Fuller Institute
For the past year, we have been working with Laser Scanning Services Company. LSSCo provides the on-site scanning and collection of data. Our firm then takes the information and creates a highly detailed 3D model of the existing structure. The types of projects we have collaborated on range from currently occupied buildings to historic structures that are about to be repurposed.
What Does A Point Cloud Look Like?
Several Autodesk applications will open point clouds, but each looks a little different.
Below is laser scanned data viewed in Navisworks:
Navisworks is more often used by contractors than architects. The point cloud file is fairly legible in this application. From a bird’s eye perspective, the overall shape of the building is clear, as are the ceiling grid and light fixtures. Below is a corridor view from the same project. This view clearly illustrates the billions of points that come together to register the existing conditions, or data, of the project.
Here is a quick video of using the scan in Autodesk ReCap and Revit:
video source: Autodesk
ReCap allows the actual scan to be viewed. Remember, all of the individual scans are stitched together to make the point cloud. The scan looks photo realistic and contains quantative information! There is a measure tool that allows you to select points and identify distances. ReCap allows the user to pan, rotate, and zoom.
Below is a color scanned point cloud as it appears in Revit, the program our firm use to model projects:
What Do You Do With Point Clouds?
Point Clouds allow you to have an intelligent representation of an existing building (or room, or site, or object) to aid in the design process. Here are a few highlights of how point clouds fit into our office workflow:
- Import in Revit to create our entire ‘existing conditions’ model. Wall thickness, beam sizes, and roof slope are all there to be measured & modeled.
- View the scanned images to recall existing details and measurements. If the project isn’t right around the corner and we are trying to recall something about the building, we have the ability to access information and walk around the project much like a video game.
- Use point clouds to verify against as-built drawings. Often building owners have ‘as-built drawings’. For a long time, this was the best way to keep documents on what was built. However, there are always some inconsistencies. A building could settle. A roof joist system may be installed inches lower than stated on the drawings. All of these details can add up to big costs on a job site. We can use the scanned data and compare long before construction equipment is on site.
As BIM becomes more common place in firms of all sizes, I believe laser scanning and point clouds will not follow far behind.