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At least 1,549 records · Page 86Linked to original sources
USGS1987

Digital processing techniques and film density calibration for printing image data

Satellite image data that cover a wide range of environments are being used to make prints that represent a map type product. If a wide distribution of these products is desired, they are printed using lithographic rather than photographic procedures to reduce the cost per print. Problems are encountered in the photo lab if the film products to be used for lithographic printing have the same density range and density curve characteristics as the film used for photographic printing. A method is presented that keeps the film densities within the 1.1 range required for lithographic printing, but generates film products with contrast similar to that in photographic film for the majority of data (80 percent). Also, spatial filters can be used to enhance local detail in dark and bright regions, as well as to sharpen the final image product using edge enhancement techniques.

Conference Paper↗
USGS2002

Sand resources, regional geology, and coastal processes for shoreline restoration: case study of Barataria shoreline, Louisiana

The Louisiana barrier shoreline of Barataria Basin, which lies within the western Mississippi River delta, has undergone significant retreat during the past 100 years. The most practical restoration method to rebuild these shorelines is sand nourishment. Seismic and sonar interpretations verified with geologic samples (vibracores and borings) indicate that there are nine sand targets within the Barataria study area that meet or exceed the minimum criteria for potential resource sites. However, the near surface lithology in the basin is typically silts and clays. Locating suitable sand resources for shoreline restoration is challenging. The sand units are associated with geologic depositional systems such as ebb-tidal deltas, distributary mouth bars, and channel fill (undifferentiated fluvial or tidal inlet channels). The nine potential sand targets consist primarily of fine sand and can be delineated into three surficial and six buried features. The surficial features contain approximately 10% of the total sand resources identified. At least 90% of the sand resources need overburden sediment removed prior to use; almost 570 million yd 3 (438.5 mil m 3 ) of overburden will need to be removed if the entire resource is mined. In this study, we identified 396 to 532 mil yd 3 (305.8 to 410.8 mil m 3 ) of potential sand deposits for shoreline restoration. Previous studies using less dense survey methods greatly over-estimated sand resources available in this area. Many fluvial channels reported previously as sand-filled are mud-filled. Contrary to these previous studies, few fluvial subsystems in this region have abundant sand resources.

Louisiana↗