In ArcGIS, if you want to convert vector data from one coordinate system to another, you should usually use the Project tool in ArcToolbox. But I encountered a problem when using this tool.
The data I got is a point layer with latitude and longitude coordinates. The person who gave me this layer said the points were taken from Google Earth and should be WGS84 coordinates. However, the Xi'an 80 coordinate system is used in the project, so it is necessary to convert the WGS coordinate system to Xi'an 80. I encountered a problem when using Project to do projection conversion, as shown in the figure
Geographic Transformation, which was originally an optional parameter, has become a required parameter. And I can't find the conversion option between WGS84 and Xi'an 80 in the drop-down list.
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Found some posts on this issue in the ESRI China community. The post does not directly give a solution to this problem, but referring to the content of those posts, I tried the following method and achieved initial success. The basic idea of this method is that since Geographic Transformation must be filled in, but there is no drop-down list, then customize one.
1. First, use the Create Custom Geographic Transformation tool to define a Geographic Transformation. As shown
2. After completing the definition, use the Project tool, and you will find that the Geographic Transformation you just customized appears in the Geographic Transformation drop-down list, as shown in the figure
The green dot is gone and it's ready to run. There is one thing to note here, the Geographic Transformation in the third picture should be the same as the Geographic Transformation in the second picture. But I didn't take any screenshots when I first started doing this. The pictures were taken later, so they have different names in the pictures. This is just an indication.
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This method has two pitfalls
1. In Figure 2, I filled in the Method parameter based on an example on the Internet. I don't know what it means;
2. In Figure 2, Parameters seems to be the "seven parameters" of projection transformation. All seven parameters are 0, which seems inappropriate. I did a check, loaded both the pre-transformed data and the transformed data into ArcMap and found that they were coincident. However, since the data before and after conversion belong to different coordinate systems, ArcMap must have converted one of them when loading the data. So even if they coincide, it's not entirely sure that this method is correct.
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references
http://bbs.esrichina-bj.cn/ESRI/viewthread.php?tid=46004