The multi-billion dollar a year activities linking aerial imagery with geospatial technologies expands more rapidly than you can blink an eye. Government and commercial contracts dominate the growth, especially for military, security, agriculture, and forestry applications.
Within this hive of activity, several trends stand out. Cloud hosting is becoming the norm. Developers and end users alike are requesting imagery with higher spatial and temporal resolution. The explosive growth of small unmanned aerial systems fuels the expectations for imagery that is uniquely optimized for the client.
What does this mean for us? How is it changing our workflows? Well, like most things, it depends. One service or product might disappear but something else is likely to fill its slot, in one way or another. For example, as it transitions to cloud-based hosting of its services, USGS has announced a series of updates that affect several image collections. The impact could be a simple change of a URL to reflect a new server source, but other changes are more substantial. By fall 2017, the web service supporting access to the High Resolution Orthoimagery will no longer be supported, though that collection will continue to fill certain imagery gaps within the dynamic NAIP Plus service.
Changes like these reflect USGS’ evolving shift away from imagery acquisition and management and towards its mission-central 3DEP and LiDAR products, as well as its hydrologic data. Together these services are critical elements of its cornerstone Topo program. Imagery has become a commodity that many agents and agencies cover, and it makes strategic sense for USGS to work with and rely on other partners in the imagery realm.
What we’re already seeing, from USGS and other agencies, is a willingness to cross-list products, sources, and services across these numerous partners. It feels a little like a competition to see who can provide a user-friendly interface that allows one to search, browse, select, and access imagery across all geographies, scales, sensors, platforms, and time frames. Navigating these browser-based portals is both an embarrassment of riches and a frustrating confrontation with a mind-boggling assortment of acronymic options.
Here are a few highlights:
Aerial imagery collected at lower altitudes is now driven by the UAS market, but the government’s collection of orthoimagery remains an important asset. For now, both the HRO and NAIP orthoimagery collections are available via the National Map, fast becoming the default mothership of public vector and raster geodata.
Meanwhile, the U.S. Department of Agriculture just modified its Geospatial Data Gateway so that the terabytes of its NAIP collection can be found only through the direct download option. USDA provides searching and ordering of its historical imagery, such as that distributed by its Aerial Photography Field Office, by a webmapand a GIS Dataset Viewer.
If you are interested in both aerial imagery as well as satellite imagery, why not start with a portal that provides them both: USGS’s Earth Explorer, or the next generation of USGS’s GloVis. These two venues exemplify the overlapping Venn diagram of options for finding imagery. The collections available via GloVis Next can also be found at Earth Explorer, though the different searching and selecting experiences seem to make users loyal to one or the other.
And that desire – to feel confident, competent, and comfortable – is a motivating factor behind the other search and discovery sites being designed and made available. This is particularly important when confronted with complex products derived from increasingly diverse sensors, instruments, and platforms. Have you looked lately at NASA’s Reverb? Its menu is a smorgasbord for earth scientists.
Therefore, logical and intuitive filters are the most important functionality for these sites. Being able to set limits on percent cloud cover, satellite source, available bands, and dates are the minimum requirements, but targeted and effective searches that allow searching via other metadata attributes can be highly desirable. Having visual cues to complement tabular ones – such as the display of the image footprint – is another obviously beneficial feature. But for novices to this search and selection process, navigating the options and returns can still be confusing. For example, Planet Explorer offers a pleasing approach to filtering and viewing imagery from a mix of commercial and government sources but a user may still be prompted to contact the sales office for a (free) Landsat 8 image, when the same image could be located and downloaded within a matter of minutes from numerous other sites – such as the Earth Observing System’s LandViewer or the USGS ones referenced earlier.
Commercial satellite companies entice their customers to consider the investment in their valuable resources with samples of compelling images, such as the Geoeye-1 gallery. The Japanese Himawari system has daily movies produced to highlight their real-time product. Some companies have found a niche by supporting the navigation process through multiple catalogs themselves. For instance, Harris Geospatial maintains MapMart, a site that provides one-stop shopping for multiple commercial products.
While you’re waiting for your requested data to download, explore the less mainstream ways to interact with satellite imagery. Artificial intelligence and machine learning rely on pattern detection, which means that we are training systems to recognize measurable similarities and differences in the imagery. Terrapattern is one example of how this works, and GlobalXplorer is how it can be applied to solving real problems. With Land Lines, Google captures input via digital movements and matches the shapes produced to components within images. If what you want is just to be immersed in the glory of the images themselves, EarthPattern will let you migrate your experience from your laptop screen to your living room wall. Bask in the visible portion of the electromagnetic spectrum!
Want to learn a little more? These references may be of interest.
Belward, Alan S. and Jon O. Skøien (2015). Who launched what, when and why; trends in global land-cover observation capacity from civilian earth observation satellites. ISPRS Journal of Photogrammetry and Remote Sensing, 103: 115-128. https://doi.org/10.1016/j.isprsjprs.2014.03.009.
Chen, Jun, and Ian Dowman, Songnian Li, Zhilin Li, Marguerite Madden, Jon Mills, Nicolas Paparoditis, Franz Rottensteiner, Monika Sester, Charles Toth, John Trinder, and Christian Heipke (2016). Information from imagery: ISPRS scientific vision and research agenda. ISPRS Journal of Photogrammetry and Remote Sensing, 115: 3-21. https://doi.org/10.1016/j.isprsjprs.2015.09.008.