Guide To 3D Scan A Building
And why the professionals
The technology behind 3D scans has increased dramatically over the years. Now the hardware and software are available for the average user to complete 3D scans of rooms and objects. Owners of construction companies can even get equipment and software to scan buildings and make models based on those scans. But should you?
This article will discuss the different types of 3D scanners available to you, the types of scanners you can use to scan your building, and the different applications those scans might have. It will also look at why it is usually best to go with the pros for your 3D building scan.
3d scan in practical use
A 3D scan has a lot of different applications, from architecture to creating a digitized library. For example, The Smithsonian Institute is currently scanning different exhibits to preserve their collection.
In this article, you will be looking at a 3D building scan. But even this seemingly narrow application of the technology can have a big impact, and a variety of people can benefit from the technology:
- Construction companies
- Interior designers
- Individuals charged with preserving historical structures or landmarks
All these fields can benefit from 3D scans in a variety of ways. Architects can use 3D scanning technology to conduct site evaluations. And similarly, transportation engineers can use the tech to do land surveys for road construction. Construction companies can use scans to check progress on large projects.
Archeologists can use scans to evaluate sites that may be fragile to inspect physically. Similarly, interior designers can use scans to create models of proposed room designs.
Read also our article “What Is 3D Laser Scanning Used For“
You may have guessed from the word itself, but photogrammetry creates a 3D scan of a building through the use of photographs. This technology is probably the most readily available to the average user. If you have a decent smartphone or tablet, you can create a 3D scan using photogrammetry. Photogrammetry has some big positives going for it:
- The technology is easy to use.
- It has the potential for a high-resolution scan.
- It requires a lower upfront investment, and it can even be free.
- Just about anyone can do it.
For these reasons, photogrammetry is most often used by hobbyists or professionals for smaller applications. While you could scan a building using this method, it is not the most practical. It would take thousands of photographs, if not tens of thousands, to properly map out the building.
A photogrammetry scan of a building would also necessitate the use of drones to get the upper levels and the roof. Once again, it could be done, but it might require more effort than it is worth, especially when it comes to cataloging all those photos and forming them into a model.
Time-of-Flight and Phase-Shift Scanners are two slightly different types of laser scanners that are best applied to scan large objects and structures, like buildings. Both scanners use a laser that is mounted on a tripod and can collect information in 360 degrees by pointing the laser at a mirror that swivels in all directions. But the two methods are different in how they acquire data.
Time-of-Flight scanners are based on the knowledge of the speed of light. If you know how fast light travels between the sensor and the object, then you can figure out the distance between those two objects. As a result, Time-of-Flight scanners are able to create highly detailed, accurate scans of buildings.
Phase-shift scanners use a similar mechanism to be able to scan a large area in a circle around the scanner, but they use a slightly different approach. Phase-shift scanners adjust the power of the laser pulse that it sends out and compares the different phases, hence its name.
These scanners are highly accurate and very fast when they work within the range to which they are suited. Phase-shift lasers work best at 300 meters or less, while time-of-flight scanners work best at 1000 meters or less. It should go without saying, but these scanners also require training and expertise to operate correctly.
Limitations, advantages, and applications
While both scanners have advantages, they both face limitations as well. Time-of-Flight (ToF) scanners can scan at longer distances, but they are slower at scanning. Their data point collection rate can usually be measured in the thousands or, at their slowest, hundreds.
This limitation is inherent in the technology and the class of laser. Also, if ToF scanners used a more powerful laser, they would be dangerous, especially to the eyes. However, they have a greater degree of flexibility given the fact that they can scan objects close up and far away.
Phase-shift lasers are much faster than ToF because they send varying pulses through a constant stream. They acquire data at a rate that can be measured in the hundreds of thousands or even the millions. However, they are limited in their range, and the faster they operate, the closer their range has to be.
It is for this reason that some services use both types of lasers depending on the application. Because of their ability to reach up to a kilometer, ToF lasers are best used to scan the exterior of buildings. On the other hand, phase-shift lasers can scan in greater detail and shorter ranges, so they are best used in interior settings.
Scanning is more than scanning
A 3D scan of a building is more than just the hardware, or even the ability to use it. The information you collect from a scan is used to create a model. It does not just pop out of the computer fully formed and ready to be analyzed.
The information or raw data that is collected by the scan is called a point cloud and can be used to create a CAD model. This is what you would use for reference in your project.
The point cloud made by the scan can also be used to create:
- Plan view or elevation view drawings
- Documentation of a building as it stands (as in before a remodel)
- Presentations (pictures and detailed views of the model for a committee)
- Integration of business information modeling (BIM)
How software applies scan data
Generally speaking, scanning software goes through two steps with the data that is provided by the scan:
For the software to turn the data into a useful image, it must first register all the points and put them together in a way that accurately reflects reality. This can be more difficult than it sounds. Sometimes the software has to work off of targets that have been placed into the scan, and sometimes it is able to work without them.
The software also has to be able to determine the areas of overlap where multiple scans have been completed in order to piece together a comprehensive picture. This requires manual checking of the data so that errors do not compound.
Once the software has registered all the data, it can begin the process of completing a visualization, which is like computer-generated imagery. 3D modeling, which is different though it takes place in the same step, is completed with computer-aided design (CAD) and can be used to make intricate plans of buildings and facilities.
How much software
Because this software has to deal with so much data, sometimes services will use two different programs for the two different steps, one to handle just the registration and one to hand just the visualization or modeling. Other software packages are large enough to handle both steps within one program.
In the past, manufacturers of scanners sold software to go with the scanner itself. But now, you can buy software independently of the scanner, which can integrate with many scanner models.
Why use professionals to 3d scan a building?
There are a lot of different aspects to the answer to this question. Of course, every situation is different, but you need to look at this question from three different vantage points to get the most accurate answer.
The best way to consider the benefit of a service is to look at what you would need if you were to do the service yourself. Since construction is the most likely industry to be using this kind of scanning, this article will look at these factors from that point of view.
Before you look at equipment, processes, or money, you have to consider the most basic element of every service that anyone provides: Knowledge. Why do you pay for your favorite burger instead of making it yourself? Because someone else knows how to make your favorite burger. They do it all the time.
While that may sound like a simple analogy, there is not a service industry where that analogy breaks down. So, the reason you want a professional service to 3D scan your building is because they know how to do it. They have been trained in the equipment, the application of the equipment, and the development of the data.
You may object that anyone can figure those things out. You are right! But if you have not figured it out, that means you have to honestly ask yourself what you are willing to invest in doing that. This article will talk more about money in a moment, but for now, take a moment to consider a couple of other factors:
If you want to do a 3D scan of a building yourself, you have to invest the time to evaluate and purchase the equipment necessary for that, and you have to invest in the education to understand the ins and outs of the equipment and its application.
For the sake of argument, say you know a little bit about how to do a 3D scan, you have seen it done a hundred times, and you think you want to do it yourself. What about personal experience? If knowledge is the most basic element of any service, certainly experience comes in at a close second. Some would even say it ties with knowledge.
Scanners collect millions of dots of data, huge amounts of raw information, and yet if one or a couple of points are off in some way, that could leave big gaps in your model. Are you sure you know all the things that could go wrong or need to be adjusted for when scanning a building?
What about when you are forming the data into a model? Have you been trained in how to create one? Do you know how best to apply that information to your project or your business? Experience makes the difference in your ability to do something versus your ability to do something well.
Ultimately running a business means you have to bring all your decisions down to the bottom line. It is not going to benefit your business if it does not make you money or save you money.
In looking at choosing a professional scanning service versus doing a 3D scan of a building yourself, you have to ask a fundamental question. Will this provide long or short-term cost savings that will benefit your company in the long run?
First, here is some information about the initial investment:
- Time-of-flight lasers range between roughly $30,000 and $150,000. Those are the cheap ones.
- Phase-shift lasers range between $80,000 and $165,000.
That is a steep investment. To be fair, for the sake of comparison, scanning services can start by costing as much as $4,000 a day and can easily go up from there depending on the size, complexity, and duration of a job.
If you are regularly paying for scanning services at that amount of money and with a high frequency throughout the year, then it may be worth it to you to invest in a laser scanner.
But investing in the equipment is just the beginning. You also need knowledge, and not only will that cost money, but it will also cost time.
You will have to learn how to use the equipment and the modeling software, or you will have to pay an employee to learn how to do so. That means all the things that go into labor costs, or in some cases, maybe even hiring a new person to take over this job.
As any college graduate learns, knowledge is not the only thing that you need. You need personal experience to be able to do a job well, and experience levels its own cost.
This means that investing in the equipment and the knowledge to be able to do the 3D scan yourself requires the inevitable mistake by you or your employee to gain the experience to do the scan well. Failure is, after all, the ultimate teacher.
A faulty 3D scan could potentially result in poor construction. This could affect everything from the structure of the building to the electrical conduit to the water lines. A mistake could result in redoing what was improperly done, and that costs time and money.
When things have to be redone, that creates a scheduling nightmare for the rest of the project. The result is usually that the whole project is set back.
What can a scan service provide?
A professional service handles all the things that you cannot because you lack the knowledge to do it.
- It collects the information and structures it in a way that makes sense.
- It can evaluate structures that are in progress as well as structures that are fully built.
- It provides accurate results quickly because the people involved are trained in not only collecting the information but also disseminating it in a way that is customized to your project.
- A good scanning service will also provide training on how to use the information.
Obviously, in construction, timelines are an issue. Scanning services are aware of this and often can work in close relationship with a construction company (if they are locally or regionally based) to quickly provide onsite evaluation and results so that the schedule is thrown off dramatically.
Savings in cost
While the use of a service seems pricey, it can actually save money. With a 3D scan, you can get accurate measurements and a workable model of a building that would take hours to replicate with a camera and a tape measure, especially for large structures.
But the savings do not end with the labor of data collection. Accurate plans of a building (with appropriate measurements), especially those that are clear and highly detailed, save a lot of time in the planning process of a large project.
Furthermore, as any lead on a construction job knows, the more accurate, clear, and thorough the planning is for a job, the fewer mistakes there are in the implementation of the project’s objectives. If you think of how much time and money a poorly conceived model wastes, an accurately rendered model saves that much as well.
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