Bathymetric grid of Macquarie Island Region (2004)

This metadata record is a modified child record of an original parent record originating from custodians of data associated with Geoscience Australia (The identifier of the parent record is ANZCW0703006701, and can be found on the Australian Spatial Data Directory website - see the URL given below).A bathymetric grid of the Macquarie Island Region (Longitudes 151 E and 167 E, Latitudes 48 S and 62 S) was produced. In doing so, the individual datasets used were closely examined and any deficiencies noted for further follow up or were rectified immediately and the changes documented. These datasets include modern multibeam data, coastline data obtained from georeferenced SPOT imagery, hydrographic quality data, echosounder data from research and fishing vessels and satellite derived bathymetric data.A hierarchical system was employed whereby the best and most extensive datasets were gridded first and applied as a mask to the next best dataset. A new masking grid would be formed from these datasets to pass non-overlapping data in the next best dataset. This procedure was employed until finally the satellite data were masked. All the various levels of masked data were then brought together by the gridding algorithm (Intrepid and Desmond Fitzgerald Associates) and an ERMapper format grid produced.A grid cell size of 0.00225 (nominal 250m) was used with many iterations of minimum curvature gridding and several passes of smoothing.The final grid is available in geotiff, ArcInfo ascii and xyz text formats.A detailed report of the work completed is also available.

本元数据记录（metadata record）为一份修改后的子记录，其原始父记录源自澳大利亚地球科学局（Geoscience Australia）相关数据的托管方；该父记录的标识符为ANZCW0703006701，可在澳大利亚空间数据目录网站查询，具体网址见下文。本次研究生成了麦夸里岛海域（经度范围151°E至167°E，纬度范围48°S至62°S）的水深栅格数据集。处理过程中，项目组对所用的各原始数据集进行了严格核查，记录下所有缺陷并跟进整改，或立即修正并留存变更记录。所涉数据集包括：现代化多波束数据、经地理配准的SPOT影像海岸线数据、水文质量级数据、科研与捕捞船舶的回声测深数据，以及卫星衍生水深数据。本次采用分级处理流程：优先对精度最高、覆盖范围最广的数据集进行栅格化，并将其作为掩膜（mask）应用于次优数据集；基于这批数据集生成新的掩膜栅格，以剔除次优数据集中与此前数据集重叠的区域，仅保留非重叠数据供后续处理，该流程持续迭代直至最终对卫星衍生水深数据施加掩膜。随后，栅格化算法（由Intrepid与Desmond Fitzgerald Associates联合开发）将各层级经掩膜处理的数据进行融合，最终生成ERMapper格式的栅格数据集。本次栅格采用0.00225的单元格尺寸（标称分辨率250米），并经过多轮最小曲率栅格化迭代与多次平滑处理。最终生成的栅格数据集支持GeoTIFF、ArcInfo ASCII及XYZ文本三种格式。此外，本次工作的详细研究报告亦可获取。