Reality Capture Made Easy: The Complete Workflow with 3DR Site Scan
Data capture has been discouraged in many industries because it is thought to be expensive, time consuming, and it requires skilled personnel to collect and analyze data. This is particularly relevant for the AEC space. In its latest industry report, McKinsey & Company shows that construction is one of the least digitized industries, only second to agriculture and hunting. Drones are going to commoditize data capture—making it easy, cheap, and accessible to everyone. Under the new FAA Part 107 drone regulations, everyone—after passing the Remote Pilot Certificate knowledge test—can fly drones legally for commercial purposes.
However, the last thing you want on a construction site is just more data! You want this data to be actionable and already integrated into the software tools you are using every day.
With Site Scan, 3DR has built a platform that makes reality capture quick and simple, manages the data in the cloud, and pushes it to the Autodesk tools you know. The workflow from camera over cloud to Autodesk software just takes a couple of clicks.
The Job to Be Done
To showcase the complete Site Scan workflow, I would like to use a real-world example.
This silo is a part of a retired cement plant that isn’t being used anymore due to its outdated infrastructure (see Figure 1). The structure will need to be refurbished and the site redesigned for optimal operations. Site Scan was used to create an as-built model of the structure and the rest of the site to initiate the preliminary design and engineering phases.
Figure 1: The silo
Planning a Mission
The first step to any data acquisition is mission planning. With Site Scan, this planning is done completely on an iPad running the mobile app “Site Scan Field.” While a controller is required for emergency and legal reasons, gone are the days when a drone operator had to learn the intricacies of flying completely manually using the control sticks.
With Site Scan Field, the drone operator can zoom into the area of interest using familiar gestures on the iPad. Pressing “Plan Survey” will insert a standard polygon in the center of the screen (see Figure 2). You can drag this polygon to the desired area, and move or add vertices to ensure the bounding box is correct to capture all the data required. Site Scan Field will automatically build the flight path in addition to adding camera triggers in order to optimally cover the area you want to survey.
Figure 2: Plan mission with Site Scan Field on iPad
Along the bottom of the screen, you can view estimated flight time to complete, ground sampling distance (GSD) or resolution, area covered, and number of photos to be captured. The flight plan can be adjusted by increasing the flight altitude or by changing the bearing of the flight lines. As these options are adjusted, flight information is updated in real time so you can see how raising altitude adversely affects GSD, but lowers the estimated flight time to cover the same area.
Flying Site Scan
After the flight has been planned, all you have to do is press “Fly Survey.” The app will run through a set of checklists to ensure the aircraft is ready for takeoff. These checks make sure all components of the system are functioning properly. Once the checklist is complete, a green slider appears. When ready to start, you can swipe the slider to the right. The drone will boot up, spin the props, and take off autonomously.
Figure 3: Site Scan with Sony R10C in flight
After takeoff, the drone flies itself. Your job is to keep an eye on the system to make sure everything is operating normally. The aircraft flies a back and forth pattern that’s similar to mowing a lawn. During the mission, the autopilot triggers the Sony R10C camera, a large 20 megapixel APS-C sensor, which is the largest imaging sensor carried by a drone weighing less than 2 kilograms. Site Scan is able to cover up to 30 acres in one flight at a resolution of one inch per pixel. With the three batteries included with the system, the operator can acquire up to 90 acres of data in only 45 minutes.
There are a number of safety failsafes that the autopilot handles automatically. For instance, if the battery drains faster than planned, or if the drone loses connection with the controller, the autopilot will trigger a return-to-home sequence. Before starting the mission, you should set a “return home altitude,” which is the minimum safe altitude at which the drone can fly back home once failsafe is triggered.
Once the drone lands itself from where it took off, you can wirelessly download the images to your iPad. This is done by pressing the “Download image” button at the bottom of the screen. Once downloaded you can review the full resolution images on the iPad (see Figure 4) while you are is still on site. This is important for quality assurance as one can quickly check if all the images have been acquired before leaving the site.
Figure 4: Review images in Site Scan Field
Now that you have all the images you need, you can connect the iPad to the Internet and safely upload all data to the cloud. If you have a 4G-enabled iPad you can do this step while you are still in the field and your colleague in the office can view the images right away by logging into the web application, “Site Scan Manager.” Otherwise, you can upload the data when connected to Wi-Fi.
Processing Your Data
The next part of the workflow is done from the office using the Site Scan Manager web application. Just login to sitescan.3dr.com with your account credentials and the first thing you will see are all the missions you’ve flown with your Site Scan drone. The mission you just flew will be visible on the top left side and by clicking on it, you’ll be able to review all the details. You can flip through the images in the browser, viewing the full-quality data so that proper coverage and QC checks can be made without having to download any data locally. These images can also be shared outside the 3DR Cloud by generating a “share link.” Sending this link to anyone will allow them to download the images without having to log into Site Scan themselves. This is a perfect method for sharing data outside your organization.
In order to create data products such as orthos, point clouds, and 3D meshes, a photogrammetric process needs to take place. With Site Scan, this processing takes place in the cloud, using the Autodesk ReCap stitching engine.
Included in the Site Scan package is unlimited cloud storage and processing, so the data products can be generated as many times as needed. To start the process, click the “Process” button. This will bring up a pop-up with multiple file formats from which to choose. You can select one or many file types to process at the same time. The following are available file types the engine can export:
- Ortho (orthorectified georeferenced image and raster DEM)
- RCM (ReCap 3D mesh)
- RCS (ReCap point cloud)
- FBX (Autodesk 3D mesh)
- OBJ (Open-source 3D mesh)
- LAS (Open-source point cloud)
Once the processing has been kicked off, the models will be generated in less than an hour for ~30 images to 6 hours for 500 images. As with the raw image files, these models can be shared outside the organization using a share link. The orthophoto can be reviewed in the browser, overlaid on top of a basemap for location and quality checking (see Figure 5).
Figure 5: View ortho in Site Scan Manager
Use with Autodesk Tools
Even though the 2D and 3D files created by Site Scan can be imported in any Autodesk tool, I would like to showcase an example using Autodesk ®ReCap 360™ Pro and ReMake. ReCap Pro 360 is a desktop software that manipulates point cloud files. You can easily import the RCS (point cloud) file created from Site Scan straight into ReCap 360 Pro (see Figure 6).
Figure 6: Silo point cloud imported in ReCap 360
There are a lot of points around the edges of the model that aren’t very accurate due to the drone also capturing low-quality data outside the selected area. You can quickly select the points you want to keep and delete the rest. In order to simplify the use of the point cloud, you can create regions for buildings, terrain, and other features. Doing this splits the point cloud into separate files for each region. This will speed up the software when analyzing the point cloud of reach region.
The first task is to determine the roof area so that a cost estimate can be created for a new roof. Recap 360 Pro makes this easy by using a distance tool that snaps to the points, ensuring accurate dimension (see Figure 7).
Figure 7: Calculate the silo roof area with ReCap 360
The second task is to determine the size of the trash pile next to the silo. This will help us find out how many trucks to order to haul out the trash. You can use the RCM (3D mesh) file inside of Autodesk ReMake to “Slice & Fill” the pile to determine the volume. ReMake is a simple Autodesk tool to edit and analyze 3D meshes. As ReMake opens RCM files natively, importing is simple.
Figure 8: Calculate volume in ReCap 360 Pro
To calculate the volume, select the pile or feature and delete everything except the selected feature. Next, perform a slice and fill to create a plane that the software will use as a bottom plane of the pile. After the feature has been “solidified,” the ReMake Mesh Report will show the volume of the trash pile (see Figure 8).
The workflow couldn’t be easier! Reality capture generates value for business in AEC across all stages of a construction project, from preliminary design to earthwork, construction process, and maintenance. We typically see clients start using Site Scan for a specific use case and then quickly realize they can successfully deploy it in other phases as well. As it seamlessly integrates into Autodesk A360, customers can quickly deploy it on projects without having to learn new tools or changing workflows.
Finally, Site Scan is built to evolve. We are constantly working on new features for the Field and Manager app. I would love to hear from you regarding the current Site Scan functionality and features you would like to see added or enhanced, so feel free to email me anytime.
What’s in the Box
The complete Site Scan package comes with everything you need to put the best sensor in the sky, process the aerial data, and push it to your Autodesk tools. The box contains:
- Site Scan drone and controller
- New Sony R10C camera + 32Gb SD card
- Camera gimbal
- Two lenses
- 3 Batteries
- Rugged hard case
The yearly software license includes unlimited cloud storage and processing. Customers also have a direct line to our success engineers and a worry-free drone replacement per year.
Kevin Sartori is a Robotics Engineer by training based in Berkeley, California. Early in his career he was part of the founding team of the open source PixHawk UAV autopilot. Later, as a strategy management consultant for BCG in Switzerland he worked with industrial goods and heavy infrastructure clients to optimize their business operations in Europe. Today, he is Product Marketing Manager at 3DR and can combine his passion for helping clients improve their businesses with UAVs. Kevin can be reached for questions at firstname.lastname@example.org. For more information on Site Scan visit www.3dr.com.
 "Imagining Construction’s Digital Future," McKinsey & Company, June 2016, http://www.mckinsey.com/industries/capital-projects-and-infrastructure/our-insights/imagining-constructions-digital-future