Exploring 1938 San Francisco through aerial photography in Google Earth

Exploring 1938 San Francisco through aerial photography in Google Earth:

Editors Note: Today’s guest author is David Rumsey, President of Cartography Associates and founder of the David Rumsey Map Collection, an online archive of historical maps and cartographic materials. Additional pieces from this collection can be viewed in Google Earth by browsing the Rumsey Historical Maps layer.

In August of 1938, a pioneer of aerial photography, Harrison Ryker, worked with pilots out of Oakland Airport to create a series of high resolution images of San Francisco. Each pilot flew from north to south, completing about 12 passes to create a group of vertical black-and-white photographs, overlapping each other by approximately 30 to 50 percent. The result was 164 large prints covering the entire city at about 1 meter resolution. Residents of San Francisco can enjoy these magnificent photographs by visiting the San Francisco Public Library. But if you don’t happen to be visiting the Bay Area anytime soon, you can also enjoy the entire collection online, courtesy of the David Rumsey Map Collection.

While cataloging these historic images, our team geo-referenced each photo to create a mosaic of all the images, corrected for terrain variation, lens distortion, and variance of angle. This was a challenging task because we did not have any records of the project’s camera calibration report, lens used, or any other specifics on how the original photos were produced. Rather, we had to rely on placing ground control points in the correct places to get the desired accuracy. Glenn Bachmann of the Rumsey Map Collection led this project, the results of which allow the 1938 imagery to be overlaid on current satellite views of the city in Google Earth when you turn on historical imagery for San Francisco. You can also view these historic photos in geographic context online in the Rumsey Historical Maps online gallery using the Google Earth plug-in

Composite of 1938 aerial photos of San Francisco

The individual aerial photos that make up the mosaic above of the entire city of San Francisco are each 50 cm high and 60 cm wide, with an effective scale of 1:2,000. The prints are in very good condition with high contrast and sharp detail, as you can see in the example below of the area around the Ferry Building at the foot of Market Street.

Aerial Photograph 18, area around the Ferry Building in San Francisco, 1938

It is endlessly fascinating to compare the city in 1938 to the current landscape. The area around the old Mission Bay has undergone a huge transformation: you can see the old Southern Pacific Railroad round house, which is now transforming into the University of California’s Mission Bay Campus.

Detail of Aerial Photograph 14, Mission Bay Railroad Yards, Southern Pacific Round House, San Francisco, 1938

Another part of the city that has experienced tremendous growth are the sand dunes of the Outer Sunset district, now filled in with the Doelger housing developments of the 1940’s.

Aerial Photograph 148, Sand dunes in the outer Sunset District, San Francisco, 1938

Some of the images show parts of the cities that are no longer part of the modern landscape. Below you can see the cemeteries around Lone Mountain that were moved to Colma in the 1940’s.

Aerial Photograph 85, Calvary and Laurel Hill Cemeteries, San Francisco, 1938

Learning more about the creator of this historical archive proved to be nearly as much of a challenge as geo-referencing and cataloging his work. After much sleuthing, Dan Holmes of the Rumsey Map Collection was able to uncover more detail about Harrison Ryker’s life and work online. You can read more about Mr. Ryker in our blog post about the aerial photographs on the David Rumsey Map Collection website.

We are grateful to the San Francisco Public Library and Susan Goldstein of the library’s San Francisco History Center for making these amazing photographs available to the public, and for saving and preserving them for the past 74 years! 

This is an exciting time for historical aerial photography. New technology creates a platform for these images to be scanned, georectified, mosaicked and enjoyed by people all over the globe. Google Earth and Google Maps give new life to these images, pulling them out of the archives and encouraging comparison to present-day imagery. These photographs combine the best aspects of photographic veracity and immediacy with the scale, artistry, and cartographic tools of mapping. It is like combining a photograph and a map of the same place, together. We hope that more of these aerial photographs will be scanned and geo-referenced, covering all parts of our globe, helping us to see in detail how the world looked from above, long ago. 

Posted by David Rumsey, founder of the David Rumsey Map Collection