Six-inch resolution image captured using Applanix DSS medium-format digital system. Photo courtesy of Cornerstone Mapping.

Innovative thinking and a keen strategic perspective on the growth potential of digital aerial imaging has meant big business for a small U.S. aerial survey and remote sensing company in Nebraska. Identifying the right tool for the job has been key to the company's success.

Operationally effective digital aerial camera systems have had a tremendous impact on the airborne geospatial community since their introduction little more than five years ago. Although many users viewed the technology with some trepidation at the outset, it has dovetailed in today's geospatial environment. Its seamless integration with softcopy photogrammetry has successfully pushed the total digital workplace from data acquisition through to data delivery. Consequently, the all-digital work environment is now a reality-streamlined, efficient and effective.

Medium-format Imaging Systems

The cost associated with moving from film-based systems to airborne digital imaging is often a stumbling block for many smaller organizations. The transition to a large-format digital camera can require a huge investment in both time and expense. However, a practical alternative to the large-format digital camera systems exists today with the advent of medium-format imaging technology, which has improved in both quality and application potential. Medium-format imaging, as the term suggests, is not really designed to undertake large block topographic mapping projects where the format would require many times the number of images to achieve the same area coverage produced with a large-format digital camera. But for the right applications, medium-format technology makes perfect sense.

Currently, the majority of medium-format digital cameras used for airborne applications are primarily operated in conjunction with airborne LiDAR, where both systems utilize a common GPS/IMU (Global Positioning System/ Inertial Measurement Unit) technology to provide the direct georeferencing component to both image and point cloud data. Being format-compatible, these systems work extremely well together and are most often used for corridor-type projects, such as pipeline or transmission line surveys, or coastal zone mapping.

Medium-format imaging systems utilizing direct georeferencing are providing small business owners with a viable alternative to the large-format digital cameras currently on the market. Complete turnkey systems that include color and CIR (color infrared) capability, direct georeferencing, flight management systems, and a comprehensive data post-processing software package are serious contenders for a slice of the airborne geospatial market.

With these attributes in mind, Aaron Schepers, owner and president of Cornerstone Mapping Inc. of Lincoln, Neb., a solutions company offering high-end imaging capabilities integrated with GIS, started a completely digital mapping operation in 2002. The technology his firm uses is tailored for his project-specific client base, which includes farming associations, surveying firms and urban planning departments.

Easy single-person operation and direct georeferencing produce desired results. Photo courtesy of Cornerstone Mapping.

The Small Company Perspective

Cornerstone Mapping was formed with a mission to provide high-resolution digital imaging products for integration with the burgeoning GIS community in Nebraska. A small operation, Cornerstone Mapping operates with a multitask-oriented staff. The company operates a single-engine Cessna 182 configured for aerial survey and remote sensing projects formerly thought to be niche market applications but now considered as contracts with mainstream revenue potential.

Small block photogrammetric mapping, golf course planimetry and turf management, corridor surveys, strip mapping, environmental monitoring and agricultural change detection are among the company's main projects. All are undertaken successfully and efficiently using an Applanix DSS medium-format digital system. The system integrates an automatically controlled azimuth mount, flight management system and data processing computer. In addition, Cornerstone Mapping works closely with the state and federal agencies to monitor irrigation use, river and wildlife habitats in an effort to sustain the natural environment by providing high-quality color and CIR digital imagery to identify vegetation, water and soil features.

Schepers has been involved with the geospatial community for a number of years and had recognized the increasing need within the profession for accessible and affordable digital imagery. The requests for a digital product came primarily from local organizations implementing GIS that required aerial data for a variety of needs, from base map update information to location-specific content detail for small municipalities, cadastral surveys and municipal infrastructure planning.

"Generating airborne geospatial information can be an expensive enterprise when you consider the costs involved in setting up a business or just staying current with the purchase of the latest innovations in equipment and technology," Schepers says. Even for the big players in the profession, making the jump from film-based image acquisition to the large-format digital camera is a serious consideration. For Schepers and Cornerstone Mapping, the decision was driven by the industry's demand for digital imaging products that were readily accessible, easy to integrate with its GIS software and provided multi-function usability.

Maintaining a competitive edge often comes with a big price tag, which can be attributed to the advances in technology and the associated expertise required in attaining operational status as quickly as possible. Medium-format digital imaging is gaining popularity from a cost standpoint (less expensive than its large-format counterparts) and because some systems like the DSS are easily and quickly installed in a small aircraft or helicopter for rapid utilization. As a fully integrated system, an efficient medium-format digital imaging system will take an airborne project from the planning stage to image capture to data processing and final product delivery with a plan, fly and produce functionality.

"The benefits of moving to the latest technology are predominantly reduced operational costs and shortened delivery schedules," Schepers notes. "These two factors alone have a tremendous effect on how our organization approaches a project with regard to manpower and resource allocation, which for a small company is extremely important. Being able to take advantage of the system's direct georeferencing capability has changed the way we now look at niche-market projects. Eliminating the need for aerotriangulation processing and analysis [while] still being able to meet the client's accuracy requirements has been reflected in our overall budget estimation."

With the proliferation of GIS and associated technology, the ability to integrate digital image products as a way of enhancing GIS data is now commonplace. Image data sharing and enterprise-wide compatibility within government organizations and the private sector has fostered multi-use functionality. A case in point is a recent undertaking by Cornerstone Mapping in which the digital imagery from one project was utilized by several different organizations, departments and municipal services for a variety of specific purposes.

Multi-purpose Data

In the spring of 2005, Cornerstone was tasked with generating accurate, orthorectified digital imagery for Lancaster County, and for the cities of Norfolk, Grand Island, Hastings, Kearney and Lincoln. The imagery was required by several of the cities' public works departments, engineering and county assessors' offices, as well as the Lincoln Police Department and Lincoln Electric System. Two image scales were required. The cities requested six-inch resolution to enable planimetric, hydrographic and infrastructure details to be easily identified, and the county requested one-foot resolution imagery.

To meet the project's varied requirements, Cornerstone used its DSS medium-format system. The system's accurate radiometry in both color and CIR and medium-format footprint proved the ideal technology for a project of this type.

"Accurate mission planning is key to any project's success," Schepers explains. "We utilize the software's mission planning utilities to determine the best GPS availability for the flight and take advantage of the integrated in-flight task automation, which is essential in our operation. I'm the pilot, navigator and camera operator in the aircraft, so the system's single-crew capability is an absolute necessity for me."

As with most mapping applications the requirement for leaf-off imagery can often make timelines very tight, with sometimes just a small window available for carrying out the flights. Flying times can be extended with the all-digital approach to image acquisition, which is a result of the technology's ability to compensate for low-light conditions and atmospheric inconsistencies.

All of the cities except Hastings were flown with a 45% forward lap; Hastings required stereo coverage and a corresponding 60% overlap for photogrammetric data capture to generate 2' contour information. The system's direct georeferencing capability was a key factor in the rapid data turnaround and corresponding orthophoto production.

The versatility of digital imagery and its compatibility with various GISs becomes readily apparent in the multiple applications available from a single project. The Lincoln Electric System used the imagery for power line planning, analysis and right of way maintenance scheduling. The various public works departments uploaded the imagery for municipal infrastructure planning and engineering design work. The Lincoln Police Department's mobile crime unit can now call up specific property location information in its GIS, including georeferenced aerial imagery of the immediate area, to make informed decisions in assessing an established or potential crime scene.

The city of Lincoln's web page, which includes a host of government services and information on parks, recreation, public records and interactive maps, also used the imagery, making it accessible to the general public as a visual reference source. In addition, the U.S. Geological Survey has posted the imagery via its Internet GIS portal.

For small organizations like Cornerstone Mapping, a medium-format digital imaging system has proven to be the right technology at the right time. There are numerous advantages of integrating digital imagery into a GIS, not the least of which is an enterprise-wide sharing capability that puts everyone on the same page. Efficient and economical, medium-format technology has allowed Schepers to offer his customers the latest in spatial analysis tools without compromise.