NANP1M.TIF - North Anacapa Passage sidescan sonar backscatter image in nearshore Benthic Habitat mapping Project S. California map Series. (UTM 10N, NAD83)

The sidescan sonar image of the nearshore seafloor (0 to 100 m water depths) of the North Anacapa Passage area was mosaicked from data collected in 2000. A Klein 2000 sidescan system was used for geophysical surveying. A Triton Elics Isis brand side-scan data recording system was used on the cruise. The 1998 survey was navigated with a Leica Differential Global Positioning System (DGPS) which provided a ship position with accuracy of 1-5 m in DGPS mode. At times during the cruise differential signal was interrupted. In non-differential mode, the receiver provided a position with 30-50 m accuracy. A KVH Industries Inc. azimuth digital gyro-compass provided ship headings with 0.5 degree accuracy. Navigation data were recorded using Yo-Nav (Gann, 1992). The sidescan fish was towed approximately 30 m above the seafloor. The distance of the fish behind the ship was not known during this survey and must be estimated when the data are processed in order to produce the sidescan image mosaics. The resolution of the processed data mosaics is 0.2 m. The data are presented here at a resolution of 1 m. This is one of a collection of digital files of a geographic information system of spatially referenced data related to the USGS Coastal and Marine Geology Program Nearshore Benthic Habitat Mapping Project. The sidescan data were processed using USGS MIPS sonar processing software (Chavez, 1984). See <http://walrus.wr.usgs.gov/nearshorehab> for more information about this data set.

北阿纳卡帕航道区域近岸海底（水深0至100米）的侧扫声呐（sidescan sonar）图像，基于2000年采集的实测数据拼接镶嵌而成。本次地球物理勘测采用Klein 2000型侧扫系统，航次中使用了Triton Elics Isis品牌的侧扫数据记录系统。
1998年的勘测作业依托徕卡差分全球定位系统（Differential Global Positioning System, DGPS）进行导航，该系统在差分模式下可提供精度为1至5米的船舶位置信息。航次期间差分信号偶有中断，在非差分模式下，接收机输出的位置精度为30至50米。KVH工业股份有限公司的方位数字陀螺罗经可为船舶提供精度达0.5度的航向信息。导航数据通过Yo-Nav（Gann, 1992）软件记录存储。
侧扫声呐拖体（sidescan fish）被拖曳至海底上方约30米处，本次勘测未记录拖体相对于船舶的后向距离，在后续处理以生成侧扫图像镶嵌图时，需对该距离进行估算。经处理的数据镶嵌图分辨率为0.2米，本次发布的数据集分辨率为1米。
本数据集是美国地质调查局（USGS）海岸与海洋地质项目近岸底栖生境制图项目的空间参考地理信息系统数字文件集合之一。
侧扫数据采用USGS MIPS声呐处理软件（Chavez, 1984）完成处理。更多关于本数据集的详细信息，请参阅<http://walrus.wr.usgs.gov/nearshorehab>。