- SPECIAL REPORTS
- THE MAGAZINE
As a surveyor, how many times have you had clients say they need to see the big picture of a site or project? Obviously, this figure of speech doesn’t mean that surveyors need to provide an oversized photograph. Clients are asking for a broad set of information that enables them to take informed action. It’s a common and important requirement. More and more, delivering the big picture really does involve pictures.
Imagery has long been an important part of documenting a scene or project. Surveyors use sketches and photographs to supplement written descriptions of monuments and boundaries, structures, landforms and worksites. As digital cameras emerged in the 1990s, the new technology provided a flexible approach to documentation. Free of the delays, cost and limited capacity of film-based cameras, surveyors embraced digital photography as a way of enhancing the point-based data collection process.
In the past decade, the technology to capture images and points has made enormous gains. Today, it’s common to find a digital camera as part of a survey crew’s standard set of field equipment. The camera may be a separate device or integrated into a smartphone. Managing the photos, however, poses a challenge. Field images from these devices must be downloaded separately, and then manually linked to measured points or field notes. Some field computers, tablets and data collectors also include an integrated camera, which provides the capability of linking images directly to specific jobs or points.
Logically, the next step is to move the camera into the device that often has the best view of the project: the survey instrument. Building a digital camera into a surveying instrument provides a number of benefits in the field. But simply having a camera isn’t enough. The real benefits emerge when images and video in the field are integrated into both field and office workflows. And that’s exactly where imaging technology is headed.
For surveying applications, imaging technology integrates calibrated digital cameras into surveying field instruments. It provides the ability to collect survey data, stream video and capture panoramic still images that are oriented into the project coordinate system. In the field, software overlays survey data on the images to enable the operator to see things from the instrument’s perspective and assist in robotic operations. In the office, software overlays survey data on the panoramic images for analysis and quality control. Some systems even provide photogrammetric processing to make precise measurements from the photos.
All this adds up to a powerful and versatile combination of imaging, measurement and data management. Imaging technology is quickly taking hold in large and small companies alike. It’s delivering measurable benefits in safety, flexibility and productivity in a wide array of applications.
Capturing images for surveys has become standard field procedure for Psomas, a California-based consulting engineering firm. The company uses photographs to provide supplemental information for office technicians, and camera-equipped total stations have dramatically reduced the need for separate cameras. Using advanced survey instruments equipped with Trimble VISION technology, Psomas is able to capture digital images and utilize real-time video in the field. Because the calibrated digital camera is integrated into the telescope, the images are automatically tied to the instrument coordinates and orientation. “In the past, we used to do a lot of manual photography and capture of digital images during site surveys,” says Sean Logal, Psomas project surveyor for the Psomas Land Surveying and Mapping Group. “As the field surveyor, you needed to break down the image-taking process manually, take notes and say, ‘Here’s my pictures looking south, north, east and west, etc.’ With the application of integrated cameras, all of the field information is captured in one place and works together well when introduced into Trimble Business Center.”
For much of its work, Psomas uses spatial stations, which combine digital imaging and rapid measurement with the ability to function as a robotic total station. The technology has opened up new ways to collect and manage information while increasing speed and convenience in the field. According to Logal, the direct combination of images and dense 3D datasets gives surveyors new flexibility in providing deliverables tailored to their clients’ needs.
Psomas’s in-house surveying operation uses Trimble VX spatial stations for day-to-day operations. In addition to its traditional total station and imaging technology, the Trimble VX can capture 3D positions at up to 15 points per second. This enables crews to use scanning to capture data over large or difficult-to-access sites. For example, while working on a new extension to light rail lines in Los Angeles, Psomas needed to collect detailed data on an existing tunnel running beneath the Interstate 10 expressway. Using the Trimble VX, crews captured break lines on the tunnel walls and ceilings to describe the basic shape of the tunnel. They then scanned the interior of the tunnel using the instrument’s scanning functionality to create a 3D point cloud and captured photographs at the tunnel portals. The photos enabled office technicians to pick up any points that were not gathered in the field. The resulting datasets were given to Psomas engineering teams, who used the information to redesign and upgrade the tunnel to handle the new light rail trains.
According to Jeremy Evans, Psomas technical director for land surveying and mapping, the spatial station was able to collect the necessary tunnel data more quickly than a typical scanner. “Engineers sometimes don’t ask for everything they need,” Evans says. “With the scans and photos, we can provide additional information not originally requested.” Logal adds that Psomas likes to use its spatial stations to measure on highway design surveys and busy intersections. Using the remote video, crews can operate the instrument from a safe location. In addition to collecting points and scans of street intersections, road surfaces and the undersides of bridges and structures, the surveyors use the instrument’s imaging technology to capture photos to provide additional detail. The scanning functionality produces 3D points with sufficient density for surface modeling while bypassing much of the processing required by large, high-density point clouds.
Logal, who also uses traditional scanners and integrated survey with GNSS, likes the flexibility provided by imaging technology. In deciding how to approach a project, he looks at the needs of the client requesting the data. “It’s important to know what the client will do with the information and their ability to deal with large data sets,” he says. “If you haven't had that discussion with your client, what you offer as a deliverable may go well beyond what they really require. That's where the Trimble VX fits nicely into our project planning. The captured data can be turned around from the field to a client deliverable very quickly.”
Working at the Rocglen coal mine in New South Wales, Australia, Wes Maybury utilizes a Trimble S6 total station equipped with Trimble VISION. As the onsite surveyor, Maybury is responsible for maintaining the mine’s digital surface model. To do this, he must collect, download and check field observations, and then import the new information into the mine’s digital model. Additional work includes data collection for mine planning and construction and stakeout for roads and ramps in the mine as well as mining and production activities. He also documents geological features for the mine’s engineers and geologists.
Maybury works as a one-person crew, blending work with his total station and GNSS. Maybury routinely uses Trimble VISION to control the total station for resection and data collection. For example, following routine blasting in the mine, Maybury needed to measure the amount of rock displaced by the explosion. The measurements needed to be completed quickly, as there was only about a 30-minute window between the blast going off and the bulldozers beginning to move the newly loosened rock.
To get the best view of the site, Maybury set up the Trimble S6 close to the edge of the dropoff overlooking the work area. “There was not enough room for me to safely stand next to the instrument in that position,” Maybury says. “I performed the survey from about 10 meters (33 feet) away using the camera on the Trimble S6 as my eyes for the survey.” Maybury used the real-time video display on the TSC3 screen to identify and measure specific locations of break lines, which represent the top and toe of the slope created by the movement of the blasted rock.
With the break lines captured, Maybury then used the instrument to automatically capture a grid of points at roughly 7 meters (23 feet) spacing. In about 25 minutes, he collected 500 points. The data enabled him to compute the volume of blasted rock. “The impressive part about using the S6,” Maybury says, “is that I can be set up on the mine datum and perform the survey within a matter of minutes without having any controls in view.”
Maybury uses integrated surveying and resection to orient the total station into the mine coordinate system. He has a 360-degree prism and Trimble R6 GNSS receiver mounted on a roof rack on his vehicle. “Once I have set up the instrument, I jump in my vehicle to perform the resection,” Maybury says. “In order to get the required accuracy, I need to drive quite a distance away to complete the resection, and the instrument may lose lock. But I just use Trimble VISION to find myself on the screen so that the instrument can regain lock. It’s like having a second person working with me.”
One of the most popular applications for imaging technology lies in its ability to extend the range of the field crew. At NASA’s Langley Research Center in Virginia, a team of GIS and positioning analysts provides information to support facilities management and operations as well as data for scientific and engineering research. One example is a BIM-related project on the Langley campus. Survey teams had completed interior mapping of a building, but the interior was not tied to the Langley coordinate system. The GIS team was called in to connect the interior data to the Langley grid. Doing so called for a combination of technologies.
For the building measurement project, Langley GIS Analyst Jason Hall used a Trimble VX for the field work. The Langley campus has its own GNSS reference station, and Hall uses integrated surveying (simultaneous optical and GNSS operation) for nearly all of his work. Rather than a network of fixed points, the team uses resection to establish position and orientation for their spatial station. Hall uses the video for the resection, and follows the prism with Trimble AutoLock technology. If the instrument loses lock, the video helps to quickly find the prism.
Once the resection is completed, Hall uses the GPS search function in Trimble Access to reacquire the prism when necessary. “If you can’t look through the eyepiece, you can use video to control the instrument,” Hall says. Frequently working as a one-person crew, Hall needs to measure building corners, roof heights and façade details. Operating the instrument remotely, he collects data using the Trimble VISION system and direct reflex measurement. The approach enables Hall to measure points that are difficult to reach or in hazardous areas where access is limited.
Logal concurs with that approach. Psomas crews do a lot of architectural surveys to locate beams and connectivity within a building. Architects often want to join new work to a set of existing conditions. Using reflectorless measurement combined with imaging technology, the survey teams produce points and photos tied to the building reference system. Points in dark or inaccessible locations can be measured individually as required. “It is a robust tool to have for this sort of project,” Logal says.
Maybury is also a strong proponent of combining multiple measurement technologies. “If I was not able to scan the area, I would have still measured as many points as I could have individually,” he says. “But I estimate it would have taken me about twice as long to perform, and only would have recorded half the amount of data. Because of the Trimble VISION and scanning features, I can record redundant data in most cases. And that is much better than finding out that I did not gather enough information.”
Logal agrees. “If you’ve got the ability to move between RTK, the total station and the vision technology and blend all those pieces together, you get a sort of data fusion,” he says. “When you put all that together you’ve got things happening simultaneously in the field that normally would be separate functions. But now you have this capability to do multiple survey functions all in the same place and space. Particularly on our design surveys, whether they’re pre-construction or preliminary surveys for a design effort, we can double the amount of data that we collect.”
In addition to the technical abilities of the spatial stations, Psomas’ Evans points to the instrument’s flexibility. Unlike a dedicated scanner, its Trimble VX is in daily use. Psomas does a lot of pipeline work, and the crew chiefs are able to use the instrument’s capability to gather dense data and photos on compressor stations and other complex facilities. The crews also use the instrument for monitoring, using direct reflex measurement to monitor soldier beams and sidewalls during excavation and construction. “The ROI is there,” Evans says. “The scanning capability generates ancillary work in the office, and it’s good, billable time.”
Evans notes that the imaging technology and spatial stations help Psomas to land projects from government and transportation agencies. Safety is a prime concern for these clients, and it’s important to keep crew members out of traffic. By using Trimble VISION and scanning to survey intersections without putting people in the street, Psomas can reduce the time needed for a survey and eliminate the need for lane closures. In the office, technicians can use photos to develop missing or additional information without the need to return to the site.
The opportunities presented by the multi-purpose spatial stations grow larger by the day. Logal calls it “a fruit salad of data.” “We’ve got so many different data sets coming from different sources,” he says. “It’s incredible how robust the data sets are and how much additional information we can produce.”