Great Central Valley Crop Map


Landsat Spectral Characterization Crop Map. Great Central Valley. 1990.
from The Graet Central Valley: California's Heartland.

Since before the dawn of the internet, I was gathering digital and film copies of images from the spce program. NASA PR slides are still in my files from visits to NASA headquters in Washington DC in 1984. In that case, I was looking for space-based images of California's Great Central Valley for the big project I was working on exploring my homeland.

Research for the Valley Project led down all sorts of interesting paths, just as the "At Mono Lake" Project had 10 years before. Some of the resources I discovered during the Mono Lake project were revisited and yielded great imagery. The U2 Spy plane 10 inch roll film mapping projects run by the USAF and USGS in the late 1960s produced some wonderful aerial images of the valley.


I don't now remember how I stumbled into a great Crop Classification project at NASA Ames in Mountain View. I met Ed Sheffner of TGS Technology who was doing a project using Landsat multi-spectral camera data and comparing into with on the ground spectral data to derive a picture of which crops were being grown, and where. Their project was limited in reach, but expanded as we talked, and I promised if they could produce a picture of the whole valley, I would certain use it in my upcoming book with the University of California Press. Ed managed to find the funding, and I was delighted to keep my promise to use the image as a full two-page spread in the book.

Their project was described in "The California Cooperative Remote Sensing Project Report in 1988.


excerpt from The Great Central Valley: California's Heartland.

Great Central Valley Crop Classification
Landsat 1985.

This image is the first crop-specific classification of the entire Central Valley completed utilizing Landsat digital data. It was assembled by staff from the Ecosystem Science and Technology Branch at Ames Research Center, a NASA facility in Mountain View, California. The area shown extends from south of Bakersfield to Red Bluff and includes approximately 95% of the Central Valley physiographic province.

Crop types were identified using digital data from the Multi-spectral Scanner (MSS) on Landsat 4 and Landsat 5. Seven Landsat frames from three orbital paths we re required to obtain complete coverage of the Central Valley. A spring scene, a mid-summer scene and a fall scene were acquired for each frame. Data values in MSS band 7 (0.8-1.1 microns) and MSS band 5 (0.6-0.7 microns) from fields of known crops and other land cover types were used to develop a classifier, or statistical model. The model was applied to the MSS bands 5 and 7 values of all picture elements (pixels) in the area of interest, and each pixel was assigned to the land cover
type it most closely resembled.

The images were created by generalizing the classification and rendering it in photographic prints. Twenty-eight cover types were reduced to fifteen to enhance the interpretability of the image. The reduction was made by combining minor crops in an "other crops" category and combining all orchards into two categories. To make a product of reasonable scale and resolution, the classification was divided into thirty-six sections. Each section contained a maximum of 1,024 columns and 1,024 rows of pixels. The sections were sampled every other pixel, enlarged by a factor of two and reproduced on color negatives.

The Central Valley crop classification was performed as part of the California Cooperative Remote Sensing Project. Participants were: National Agricultural Statistics Service, U.S. Department of Agriculture California Department of Water Resources California Crop and Livestock Reporting Service Remote Sensing Research Project,University of California, Berkeley Ecosystem Science and Technology Branch, NASA Ames Research Center

Principal investigators at NASA/Ames in Mountain View, California: C. A. Hlavka, NASA, and E. J. Sheffner, TGS Technology Inc.



gvp cover

The Great Central Valley: California's Heartland
Stephen Johnson, Gerald Haslam and Robert Dawson
$45 softbound
$75 hard cover (temporarily unavailable)
Published by University of California Press, this full color, highly evocative book has received rave reviews from the press, television and academia. Combining exquisite photography, an engrossing narrative and historical images, this book is a fine addition to your library and a digital publishing breakthrough. Now in it's second printing.264 pages, 270 color and duotone photographs.



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