883
just 1972. Left,
Center is in the
jusing and then
le floodplain of
anquilla,
ional Airport
ti resolution
s suburb,
highway skirts
Magdalena River
5 port
, are visible
ds obscure some
ty, but a great
.it the urban
Figure 5. Digitally processed Landsat TM subscene collected ovpr San Francisco on May 2, 1984. upper left Band
3, visible red, 1630 - 690 nm; upper right Band 4, near reflective infrared, /bU-900 nm; lower left, Band /,
short-wave infrared, 2080-2350 nm; lower right; Band 6, thermal infrared; 10,400-12,500 nm. Streets and land
cover patterns are apparent in the 30 m resolution imagery, as are golf course,fairways, piers, and large
industrial buildings.
water, etc.-- wmch results in different reflectance
values (Figure 3). In a computer classification of
Landsat MSS data collected over the Seattle - Tacoma
area (Gaydos & Newland, 1978), land cover classes
included Commercial-Industrial, Residential,
Pasture-Grass, Cropland, several types of forested
land, Wetland, Barren Land, and Quarries-
Transitional. Analysis of Washington, D.C. Landsat
data yielded similar urban classes, including
Commercial-Industrial-Services, Paved Surfaces,
Older Residental, Newer Residential, Disturbed Land,
Improved Open Space, Agriculture, and Forested
Land/Brushi and (Gaydos & Wray, 1978).
The urban-rural fringe presents a problem to the
80 m MSS data, for two reasons. First, residential
and other land use developments are in a transition
al state. From land clearing through construction
through landscaping tnrough maturing of vegetation
and graying of concrete, a new development has a
changing appearance both spectrally and spatially.
Secondly, the rural land use adjacent to the
urban-rural fringe is in either of three states:
natural vegetation (forested land, shrub,
grassland), agriculture/truck farming, or vacant
land. Natural vegetation is the most predictable,
spectrally, of the three states, and usually
provides the best contrast with urban land uses.
The agricultural land, unfortunately, undergoes
significant signature changes as the land changes
from plowed to emerging crop to mature crop to
harvested crop to fallow land. In the Great Lakes
region of North America, agricultural land contrasts
well with urban areas when the crops are at the
height of the growing season. The third state,
vacant land, may not contrast well with an adjacent
urban development. Forster (1980) provides detail'^
insight on residential land cover, and Jensen & Toll
(1982) suggest that texture measures may be helpful
in mapping the urban-rural fringe zone.
While transition at the urban-rural fringe causes
difficulty for land cover computer-assisted
classification and mapping, scraping the earth for
new development is detectable under most data
collection circumstances. An application of Landsat
to urban land cover change detection (using Landsat