A historic geologic map, the data for which was compiled over the course of many years by one determined man, William Smith. Completed nearly 2 centuries ago, it remains incredibly relevant.
Stanford imaged this map as a part of an ongoing project to digitize our 'large map' holdings. Although the main section of the map is split into 15 pieces, when assembled, it measures approximately 10' x 5.5' (see the below image - a picture of our Cartographic Technology Specialist, Deardra Fuzzell, provides a sense of scale. Deardra is 5'9" tall).
The map and its associated items are in 18 separate parts: 15 linen backed segments (24.75 x 22 in.), 1 small index (24.75 x 22 in.), 1 booklet (22 x 16 in.), 1 leather enrobed case (25 x 23 x 6 in.). Stanford owns two copies; the copy we chose to digitize is owned by Stanford's Special Collections department and is part of the Barchas Collection.
The digital version is made up of 253 shots and is the largest item we have digitized thus far. It is a milestone. A high resolution composite of all parts would yield an image file approximately 13Gb in size. Prior to this, the largest item imaged in our labs was a 70 x 90 inch rolled Map of Santa Clara County from 1914, which yielded a file 7.11Gb in size - See more at: One Large Feat for Stanford's Oversized Imaging Lab.
How we did it:
Imaged at 600ppi in 10 x 10 inch squares (6,000 x 6,000 pixels) with a 20% overlap between shots, what we refer to as a 'tiled workflow' using a P65+ PhaseOne scan back. Images were then downsampled to 400ppi for ease of stitching and blending in Photoshop. A level of detail akin to what a patron might see if holding a standard magnifying glass over the physical object was achieved. For instance, in the below detail one can see the grain of the paper, the weave of the linen backing cloth, and the way the pigment was applied to the map.
What we learned:
This map and its associated items were very difficult.
We learned a lot about digitizing large, finely detailed items such as this - We were able mitigate the moire issues by shooting at 600 ppi, then downsampling to 400 ppi to accomodate the file size and resource limitations of Adobe Photoshop CS6’s photomerge, blend, and manual stitching scripts functions while still maintaining a sufficient level of detail.
Through the careful efforts of DPGs photographers and staff, Stanford University Library's Special Collections visitors and online viewers alike may now safely enjoy both the beautiful fully extended object and high-resolution details of each part of this rare and historically important map.
Blog post by Digital Production Group member Wayne Vanderkuil, Lead Photographer, and Deardra Fuzzell, Cartographic Technology Specialist for the Branner Earth Sciences Library
Access to the physical and digital objects: