Figure New Earth: how to import CAD files with modified elevation datum (ellipsoid)

0. order ：

Because the altitude of yunguichuan is very high ,CAD Drawings often modify ellipsoid parameters , To ensure that the projected data match the surface better

For modified ellipsoid parameters CAD data , How to accurately import , Avoid offsets ：

1. Data ：

Engineering coordinate system CGC2000 Basic parameters of ellipsoid , Central meridian ： East longitude 105°30′,X Coordinates plus constants 0 rice ,Y Coordinates plus constants 500000 rice , The ground height of the projection plane 350 rice

 2. Generate projections prj file

2.1 download CGCS2000 / 3-degree Gauss-Kruger CM 105E Of prj file

Can pass h​​​​​​​ttps://epsg.io/​​​​​​​ website , choice CGCS2000 / 3-degree Gauss-Kruger CM 105E Download , The download results are as follows ：

 

2.2 take prj File modification

Based on known information “central_meridian” Value changed to 105.5, Increase the long semi axis in the ellipsoid parameter 350, The results are as follows ：

 

3.LSV Import the CAD Drawing

stay LSV In the toolbar , choice “ Import / export ” à“ Import CAD”, Select normal mode , And import the modified prj file .

  The final effect is as shown in the figure ：