The satellite images (Path 15, Row 42) were recorded February 05, 2000, by the enhanced thematic mapper (ETM) sensor on the Landsat 7 satellite which records 7 multispectral bands and one panchromatic channel. This image map includes spectral bands 3 (630-690 nanometers, red), 4 (775-900 nanometers, near-infrared), and 5 (1,550-1,750 nanometers, middle-infrared) and the new panchromatic band (520-900 nanometers, green to near-infrared). The spatial resolution of the input data is 30 m by 30 m for the multispectral bands and 15 m by 15 m for the panchromatic band. The imagery was geocorrected using ground control points identified on the USGS digital orthophoto quadrangles and on the panchromatic data. The panchromatic data were resampled to 7.5 m by 7.5 m resolution and enhanced by filtering (101 by 101 filter with 75-percent add-back) and tone stretching. Then, the spatial information in the panchromatic data was combined with the color information of the multispectral data through a wavelet transform-based image fusion technique (Lemeshewsky, 1999). This data fusion process attempts to preserve the spectral fidelity while sharpening the spatial resolution. The tones output from this process were further enhanced through histogram evaluation and contrast stretching. Panchromatic enhanced multispectral bands 5, 4, and 3 are shown in red, green and blue respectively on the image map. This process allows the image map to meet National Map Accuracy Standards for 1:100,000-scale maps.
The combination of a number of surface characteristics, such as vegetation type, vegetation density, soil water depth, and periphyton (algae and bacteria) dictates the amount and composition of light reflected to the satellite sensor and, therefore, the brightness, texture, and color shown in the image. Image subsets illustrate some of the common surface cover types using additions to floral assemblages suggested by Sunderson (1994). Where appropriate, water conditions at the time of imaging and soil type based on the county soil surveys are also noted.
