This image is ideally suited for monitoring urban development in California's semi-arid environment. The distinct spectral reflectance that is characteristic of building rooftops, parking lots, concrete surfaces, and asphalt roads is clearly visible circling the bay and in adjoining valleys. The area covered by this scene is currently home to over six million people. Local concerns with urban sprawl, and the loss of agricultural land, provide an impetus for tracking the urban development footprint over time. The famous Golden Gate Bridge is clearly visible spanning the entrance to the Bay.
Several islands are also visible in the scene.
The Farallon Islands, about 20 miles west of San Francisco, are a national wildlife refuge. Angel Island State Park is the largest island in the bay. Yerba Buena Island is an anchor point for the San Francisco-Oakland Bay Bridge. Alcatraz is the small island 1.5 miles north of San Francisco. Landsat data provide the spatial information and synoptic view that allow us to enhance our understanding of an area.