Vertical imagery is ideal for initial assessments, early planning, and measuring.
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. 3D modeling 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
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csengineermag.com
july 2018
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