Aerial imagery is optimizing workflow, improving collaboration, and informing smart engineering.
Engineers face several daunting, external obstacles in planning for the future. Issues range from designing communities that can accommodate growing population, addressing climate change, promoting green and sustainable practices, and combating the “D+” grade that the U.S. received on the American Society of Civil Engineers’ most recent Infrastructure Report Card.
With external challenges come internal challenges — like producing deliverables more quickly and cost effectively and collaborating with partners.
These challenges require informed decision making and a close working relationship with all project team members. They also require the use and mastery of integrated technologies. Architecture, engineering, and construction (AEC) firms are utilizing high-resolution aerial imagery integrated with various design software to improve workflows and prioritize clear communication and smart design.
Aerial imagery as a service
AEC professionals can visualize, navigate, and measure sites using aerial imagery in both ortho and multi-perspective formats. High-resolution aerial maps integrated with GIS software save time, produce better estimates, mitigate risk, reduce site visits, lower costs, and improve initial planning. When accurately geolocated, the imagery elevates overlays and design layers to clearly communicate project details to clients.
For example, consider engineers who are tasked with designing a new bridge. A team from each discipline, such as structural, civil, and environmental engineering, creates a model of the bridge with up-to-date, aerial captures of the project site overlaid on other GIS layers. All of the bridge models are combined into one composite master model for the next step — BIM modeling clash detection. High-resolution imagery in conjunction with BIM software can detect where elements of separate models clash.
Using aerial imagery, interferences are identified and corrected before construction — all from the comfort of the office. By fixing the model before the project begins, firms avoid delays, change orders, and extra costs.
Aerial imagery is also transforming the public transit sector. Local transportation agencies such as Orange County Transportation Authority and the District Department of Transportation in Washington, D.C., are using high-definition aerial base maps for project management oversight, planning, and site analysis and validating ongoing construction, including lane, roadway, and sidewalk updates.
Access to imagery
In the past, aerial imagery required time and resources to host and manage large amounts of data. Today, technologies such as Nearmap remove those obstacles by offering instant cloud-based access to imagery collections. For example, Nearmap’s MapBrowser is a web-based portal designed to help users quickly navigate its current and historic high-resolution aerial imagery. MapBrowser includes tools for measuring, analyzing, and annotating locations. More importantly, it has a simple, intuitive interface, enabling teams to make virtual site visits, compare changes over time, and identify important project details.
Location — Users can search a location by address, latitude/longitude, or dropping a pin to share with colleagues, ensuring all parties are examining the same location. This generates productive conversations without being onsite. It also reduces the need to shoot and distribute location reference photos.
Vertical versus oblique — MapBrowser offers vertical, panoramic, and oblique views. Vertical imagery is ideal for initial assessments, early planning, and measuring. Panoramic and oblique imagery are useful for more thorough visual inspection. The camera systems that capture oblique imagery also collect data that can be used to produce 3D point clouds, 3D mesh, and Digital Surface Models (DSM). Vertical imagery comes with a smaller file size, making for easy sharing. Oblique files are larger because of the detail, but can integrate into design software. Oblique files also provide accurate height measurements.
Projection — For accurate mapping, local projection is critical. Within MapBrowser, users can select different map projections based on the specific site location so that scale and measurements are accurate. For instance, the projection in Seattle differs from Fort Lauderdale, Fla., with Seattle in UTM Zone 10 and Fort Lauderdale in UTM Zone 17.
When the Earth is projected onto a flat, rectangular map surface, projection distortions can cause variations the further away from the equator. This problem is minimized with the Web Mercator Projection, a calculation within MapBrowser that effectively overlays data on top of the map and corrects distortions. Web Mercator is also used by other web-based map services such as Google, Bing, and MapQuest.
MapBrowser’s georeferenced image export uses this Web Mercator projection, so it appears exactly as it did within the program. The imagery will then integrate perfectly with BIM and GIS programs.
Resolution — MapBrowser delivers imagery at 3-inch ground sample distance, which is several times sharper than most free satellite images. Users can see features such as gutters, curbs, storm drains, and soil erosion by comparing high-resolution historical captures, including leaf-on and off imagery — the presence or lack of foliage, depending on the season.
With increased accuracy, engineers produce better estimates and significantly reduce change orders.
There is an increasing demand for 3D city models for many AEC applications. Aerial imagery helps to create impressive 3D renderings and provides a detailed base map from which all teams can work.
“When teams run into problems, it’s usually because they get to the game too late,” said Austin Reed, 3D visualization team lead at HNTB, a national civil engineering consulting firm based in Kansas City, Mo. “It’s critical all team members have access to the same, accurate data as early as possible to make precise plans and models. At HNTB, we are using high-resolution, aerial captures in almost every step of our workflow, from conceptualizing to rendering. Ultimately, the imagery goes into 3ds Max to create renderings.”
Reed said that in the past, the firm used free satellite imagery, but the low-resolution, out-of-date photos couldn’t meet their needs. “When we pulled satellite imagery into Photoshop, we lost the georeferenced data,” he said. “This information is critical to ensure that all teams are working in the same coordinate space. We don’t have that issue now that we have access to an aerial imagery MapBrowser.”
Broadly, the HNTB visualization team’s imagery workflow looks like the following:
Locate — Using vertical imagery, team members get acquainted with the project site. This is especially useful when the project is out of state.
Process — The team has access to the same accurate, georeferenced data through MapBrowser. They can view and compare historical imagery to current, see time stamps, and export the imagery with gridded tiles for better integration into 3ds Max.
“Access to exact, precise data is critical because bad input equals bad output,” Reed said.
Integrate — Users generate a DSM from aerial imagery. The 3D representation from a DSM allows professionals to detect variation in terrain, which helps them provide more precise estimates for the client.
Oblique images are imported into programs such as 3ds Max, Map3d, Recap, InfraWorks, and Civil 3D to create a 3D point cloud, which uses thousands of points to depict surfaces in a 3D space. A point cloud can then be used to create a 3D mesh, which connects the points with triangles to form a realistic-looking 3D diagram of the area.
In 3ds Max, team members can align imagery to 3ds Max origin; trace and texture terrain, curbs, sidewalks, and buildings; and match the lighting and shadows to the exact time of day to create the most realistic rendering possible. When finished, the visualization technician can export it into AutoCAD for other engineering teams.
Present — With lifelike, high-definition-quality visuals, clients are impressed and can clearly envision the result.
The detailed models are also used to educate surrounding property owners. Project managers can use the models as visual aids to illustrate different project stages, staging areas, and equipment so local business owners and residents are informed and can plan accordingly.
Over time, the challenges that face the engineering industry will change. What does not change is how engineers can solve problems — through the use of the right tools and information. Aerial imagery has elevated design tools and software, empowering engineers to make intelligent and collaborative choices.
Erin Jepperson is technical sales engineer at Nearmap (www.nearmap.com).