From the Ground Up: The sky is the limit.
March 1, 2009
Significant advances have been made in the technology available for use on mapping projects. The trend toward delivering larger projects in a compressed time frame has driven further changes. Innovative and nontraditional mapping applications have also begun to emerge, and these areas provide some exciting opportunities for future growth. Let’s review each of these trends in detail.
Some of the most impressive technology advances have occurred in digital camera technology. For example, Leica’s ADS80 pushbroom airborne sensor, which was introduced last summer, provides significantly increased data throughput, cycle time, data compression capabilities, solid-state mass memory, control and resolution compared to the earlier ADS40 technology. Intergraph’s Z/I Imaging digital mapping camera (DMC) has replaced its hard-drive in-air storage systems with solid-state disk storage (SSD) technology, which is more reliable in the often-turbulent world of airborne collection. Equally important, however, is that retrieving raw imagery from the SSD devices is considerably faster compared to using the hard-drive counterparts.
Moreover, considerable changes have taken place in the medium-format digital camera market. Applanix’s DSS 32 airborne digital sensor system was a 22-megapixel camera that measured 5,436 pixels cross track (perpendicular to the direction of flight) and 4,092 pixels along track. The company’s new DSS 439 is a 39-megapixel camera with a footprint of 7,216 pixels cross track and 5,412 pixels along track, which provides increased efficiencies in both aerial capture and office processing (resulting from fewer images) for mapping projects. Intergraph also recently released the RMK-D aerial imaging system--which provides a 6,096- by 6,500-pixel true ground resolution--to compete in the medium-format market.
But the digital camera makers have not been the only mapping hardware providers making impressive gains. LiDAR manufacturers have also been busy in the areas of full waveform digitization and multiple-pulse-in-air (MPIA) technology. A full waveform (as compared to multiple discrete returns) can allow for significantly better interpretation for some specialized LiDAR applications, while the MPIA provides for higher ground densities, which is critically important for other LiDAR applications.
Faster Delivery of Larger Projects
One of the most significant trends in mapping is the movement to very large projects with compressed time schedules. West Virginia was a harbinger of this trend when the state’s Surveying Addressing and Mapping Board (SAMB) contracted for a statewide orthophoto project in 2003. The aerial photography and mapping portion of this project was completed in a compressed time frame with delivery of map products to the state in June 2004. Notably, the imagery collection for this project was accomplished with traditional film cameras, and the elevation model was completed using conventional mapping techniques.
Most statewide projects now require a two- or three-year completion, and some projects have compressed this schedule further to require completion within a year. However, current statewide projects almost exclusively make use of newer digital cameras and LiDAR technology. These technologies enable mapping firms to provide highly accurate data for large projects at low unit costs and allow rapid delivery of mapping information for large project areas. For example, a single LiDAR sensor can complete the acquisition of 10 to 50 square miles of terrain per hour of flight (depending on the accuracy and posting requirements for a project). It would take more than 1,000 hours to complete the same area with conventional mapping techniques from stereo imagery. Also consider that it only takes 6.7 seconds to collect 1 million elevation points with a LiDAR sensor operating at 150 kHz. A stereo compiler working from controlled aerial photography would take about 18 months to collect the same number of points from the imagery.
Digital camera technology has also fueled another trend in today’s mapping environment. Modern high-end digital cameras acquire panchromatic (black and white), true color and color infrared imagery in a single pass. These imagery types are perfectly registered to one another, which allows mapping professionals to provide additional imagery products to their clients at a minimal cost because a considerable amount of the effort required to create the base imagery requirements can be re-used for the optional imagery products. For this reason, many large-area projects now include the generation of both true color and color infrared imagery. The true color imagery is most valuable in traditional engineering and mapping applications, while the color infrared imagery has significant value in a variety of environmental applications.
The trend toward large projects has resulted in increased teaming and professional cooperation among mapping firms. Most statewide projects require multiple firms to complete the acquisition and post processing in the desired time frames. Firms that compete vigorously with one another on smaller projects are often partnering for the larger ones.
The current economic downturn has had an adverse impact on large regional and statewide programs, but the new stimulus plan could change the situation considerably by putting an emphasis on geospatial information, which, in turn, would enable more effective decision making.
Nontraditional Mapping Applications
A number of areas outside of traditional engineering and surveying have begun offering new opportunities for mapping. These applications require significant forethought to maximize their effectiveness.
One example is benthic habitat mapping, which maps environments in or on the bottom of a body of water. In southeastern Florida, for instance, the NOAA Coastal Services Center (CSC) is mapping coastal lagoons to identify areas of Johnson’s seagrass. This threatened species of seagrass, which is only found in this region, serves as a food resource for other threatened and endangered species, including green sea turtles and West Indian manatees. Johnson’s seagrass thrives in areas at high risk to damage from boat propellers and water quality degradation.
Digital aerial imagery is a considerable tool that can be used for mapping the presence of seagrass and evaluating the effectiveness of regulatory measures that can impact the health of the seagrass. Mapping benthic habitat generally requires a significantly different approach when compared to the mapping of features that occur on the land. The digital imagery must be processed to maximize the ability to see into the water column, which generally results in a less-than-optimum delineation of features on the land. Also, it is critically important to use the capabilities of airborne GPS (AGPS) and inertial navigation systems (INS) to control the imagery from the air since establishing ground control points in the water is very difficult, if not impossible.
Other innovative uses of mapping also continue to thrive. For example, a few years ago our firm used low-altitude aerial photo-graphy to map the density of beach-goers on a holiday weekend. Individual cells were placed on all beach visitors, both on land and in the water. This mapping was then used in the planning process for new infrastructure for the public beach.
New and innovative mapping applications also abound from platforms other than airborne. For example, the use of 360-degree street-level imagery is only limited by our imagination. This video imagery is typically captured from a moving vehicle by a composite camera that is made up of multiple individual video cameras. The multiple video images are then combined to form a seamless 360-degree view along the path of the vehicle during capture. The street-view option found on the Google Maps Web site (www.maps.google.com) provides a general idea of the power and potential uses of this application.
Mapping is an exciting science that has seen impressive growth in many different areas. This growth has benefited a diverse group of existing clients and has opened the door for new and innovative applications of the technology.
1. Benthic Habitat Mapping, NOAA Coastal Services Center, www.csc.noaa.gov/benthic/resources/species/species1.htm.