ArcGIS Unknown Spatial Reference問題解疑shp檔案在Arcgis開啟後經常因為原有座標系無法識別而丟失資訊，出現以下提示資訊："Unknown Spatial Reference
The following data sources you added are missing spatial reference information. This data can be drawn in ArcMap, but cannot be projected."今天偶然見終於找到瞭解決方法。先給出ESRI Supporter Center關於這個問題給出的解決方案：***********************************************************************************************************Error: Unknown Spatial Reference
| Article ID: |
31999 |
| Software: |
ArcGIS - ArcEditor 9.0, 9.1, 9.2 ArcGIS - ArcInfo 9.0, 9.1, 9.2 ArcGIS - ArcView 9.0, 9.1, 9.2 |
| Platforms: |
N/A |
Error MessageAdding data to ArcMap which does not have the coordinate system or projection defined displays the following error message:
"Unknown Spatial Reference
The following data sources you added are missing spatial reference information. This data can be drawn in ArcMap, but cannot be projected."CauseThe data does not have a coordinate system or projection defined.
This message is returned for all data types which can be added to ArcMap including geodatabase feature classes, shapefiles, coverages and CAD data, as well as supported raster or image formats which do not have a coordinate system definition.Solution or WorkaroundIdentify and define the coordinate system for the data, using the Define Projection Tool in ArcToolBox > Data Management Tools > Projections and Transformations or the data's property page in ArcCatalog.***********************************************************************************************************－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－其實這個解決方案是對的，以前也按照這個方法試過，但是沒有成功，
關鍵點在這裡：ArcToolBox > Data Management Tools > Projections and Transformations >
Define Projection，這裡要給檔案加入的座標系統應當是
地理座標系統（
Geographyical Coordinate System），下一步再將投影轉換到你所要的投影系統下。－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－我覺得之前失敗原因在這裡：因為軟體無法識別空間參考資訊，所以要先定義橢球體（定義地理座標系，相當於去掉原有的投影），然後再投影（Projection）。之前我們總想一步到位，軟體本來就不識別檔案的投影資訊，你讓它轉換到另一個投影下，自然有點難為它了。關於地理座標系和投影座標系的區別就不再贅述了。 原文地址:http://smiliing.spaces.live.com/blog/cns!FB62DAD013AC3B4E!653.entry
