Fisher Massif Mapped from Landsat 7 Imagery.

Fisher Massif Features Mapped from Mosaiced Pan Sharpened Landsat 7 Imagery.FEATURE MAPPINGAn unsupervised classification was run on the final image to create an image with 12 distinct grey scale values. An automated feature extraction process was then performed in ERDAS to automatically select and extract areas of Rock and Snow. These areas were then compared with the true colour image mosaic and the boundaries were manually adjusted where necessary. All other feature types were mapped in ESRI's ArcGIS by manually tracing along and around features using a stream digitising technique. Relevant linear features were then polygonised.The accuracy of the mapping was within +/- 30m for 95% of mapped features. This is a relative accuracy as there were no control points available to provide an absolute image orientation.The datasets were converted to double precision ArcInfo Coverages in UTM Zone 42. ESRI?s ArcGIS Desktop and Workstation were used to process the vector data.The Rock and Snow features which had been automatically extracted from the image were generalised using a distance of 40m with the bend simplify option of remove redundant vertices. The lines were then splined with a grain tolerance of 20m to smooth them.The line feature coverages were cleaned with a tolerance of 0.1m. ArcEdit was then used to tidy the line work in the resultant coverage. Arcs were extended where required and overshoots were deleted. The resultant coverages were built for line and polygon topology.The polygons were attributed using the Landsat image as a backdrop. The features were then extracted into separate feature coverages. The data were attributed according to the AADC Feature Type Catalogue. The individual feature coverages were built and checked for errors. A further visual check was then performed to check the features corresponded to the image.The absolute accuracy of the features mapped is +/-280m, with a relative accuracy of +/-30m.The individual feature coverages were projected to Geographicals (WGS84).After discussions with Mike Verrier, from the AAD on 30 April 2003, it was decided that ridgelines would only be picked up where there were major variations in the surface and not where there was a small hollow in which snow was settling.

基于拼接全色锐化陆地卫星7号（Landsat 7）影像绘制的费希尔山地块（Fisher Massif）特征。
### 特征制图
对最终影像执行非监督分类，生成包含12个不同灰度值的影像。随后在ERDAS中执行自动化特征提取流程，自动选取并提取岩石与积雪区域。将提取得到的区域与真彩色拼接影像进行比对，并在必要时手动调整边界。其余所有特征类型均通过流数字化技术，在ESRI的ArcGIS中沿特征及其周边手动描边完成制图。随后将相关线性特征转换为多边形要素。
95%的制图要素的定位精度误差在±30米以内。由于无可用控制点以实现影像绝对定向，因此该精度为相对精度。
数据集被转换为UTM第42带的双精度ArcInfo Coverages格式数据。使用ESRI的ArcGIS Desktop与ArcGIS Workstation处理矢量数据。
对从影像中自动提取的岩石与积雪要素，采用40米距离阈值结合弯曲简化选项（移除冗余顶点）进行概化处理。随后对线条采用20米的容差进行样条拟合以实现平滑。以0.1米的容差对线状要素覆盖集进行拓扑清理。随后使用ArcEdit工具对生成的覆盖集中的线状要素进行整理，根据需要延伸弧段，并删除超调误差。为生成的覆盖集构建线状与多边形拓扑关系。
以陆地卫星7号（Landsat 7）影像作为底图，为多边形要素添加属性信息。随后将各要素提取至独立的要素覆盖集中。依据AADC要素类型目录（AADC Feature Type Catalogue）为数据添加属性。对各独立要素覆盖集进行构建并检查错误。随后执行进一步目视检查，以确认要素与影像内容匹配。
制图要素的绝对定位精度为±280米，相对精度为±30米。将各独立要素覆盖集投影至地理坐标系（WGS84）。
2003年4月30日，与来自AAD的Mike Verrier进行讨论后，确定仅在地表存在显著变化的区域采集山脊线，而非存在积雪堆积的小型凹陷区域。