From the air: the photographic map

The county's aerial series and the statewide orthoimagery program

The library's two series. The St. Joseph County Public Library's Local & Family History department keeps the county's early aerial photography as a map collection in its own right, cataloged in the finding aid under its own heading: a 1951 series of St. Joseph County aerial photographs — no index key survives for it, the aid notes, but many images are marked with the township and range lines of the survey grid, and the prints are stored in the workroom, viewable by appointment — and a 1957 series for which a key is available. Between them the two flights catch the county at its hinge: the farm landscape complete, the postwar subdivisions beginning at the city's edge, the Studebaker plant at full extent six and twelve years before the closing. The photographs are maps in every way that matters to this section — surveyed, indexed to the grid, and kept by the map room — and they are the earliest aerial record of the county established. The federal agricultural flights that photographed Indiana counties from the late 1930s onward are the series' known ancestors, but the county's earliest flight years were not established from the county's or the library's own pages; the gap is named rather than backfilled, and the county GIS's historic-imagery holdings — the layer the county's own National Register documentation points researchers to, "Historic Aerial Imagery — St. Joseph County GIS Website" — are the update cycle's first aerial pull.

The state's program. Modern aerial coverage is a state utility. Indiana's Geographic Information Office and the Indiana Office of Technology manage the statewide digital orthophotography program described in the state's own catalog: a series dating back to 2005, flown on a four-year cycle in three tiers of counties — St. Joseph County in the first tier, with the central band running south from Elkhart and St. Joseph counties — and delivered as cloud-optimized GeoTIFFs and the older GeoTIFF, ECW and MrSID formats on a 5,000-foot tile grid, served through the state's imagery portal and its ArcGIS Online orthoimagery viewer. The county that the 1951 flight photographed once, for a workroom drawer, is now rephotographed from the air on a four-year public cycle, and the tiles are open data, registered in the federal open-data catalog.

Sources:

1. St. Joseph County Public Library map case finding aid (20 December 2021) — the St. Joseph County Aerial Photographs: the 1951 series (no key; township and range lines marked; workroom, by appointment) and the 1957 series (key available).
2. National Register documentation for Portage Manor — the pointer to "Historic Aerial Imagery — St. Joseph County GIS Website."
3. State of Indiana (Geographic Information Office / Indiana Office of Technology), Indiana Statewide Digital Aerial Imagery Catalog — the program's own description, as registered in the Registry of Open Data: orthophotography from 2005, the four-year tier cycle, the tile grid and formats, the imagery portal and viewer.