A view from above provides valuable insight into important changes taking place on earth’s surface. In the US, for example, many states are interested in regularly documenting these changes, and do so by commissioning and compiling state maps generated from aerial photographs, taken by aircraft flying overhead. New Jersey’s aerial imagery may be found on several different websites, but are most conveniently housed in the state’s geospatial warehouse, NJGIN.
There are multiple ways that these aerial images are stored, enabling some flexibility in using these maps for a variety of applications. The first way the images may be obtained is through the Data Download portion of the information warehouse. Images from 1995 to 2015 may be downloaded, either one tile at a time, or by selecting multiple tiles. The example below, on the right, illustrates the image for Drew University campus in 2015.
Another way that images may be included is through referencing a web mapping service (.wms file) in a GIS. Where these files are accessed, they load imagery that are hosted on the NJGIN website. A list of the available .wms files is here. The .wms file is used to create the comparison image for Drew’s campus, using 1930 photos of the state (below, on left).
Another example, shown below, compares USGS Historical Topographic Maps in comparison to 2012 aerial imagery of Drew University’s campus.