To Import Low Density Data
1. Click > 
Sample Data from File. The Import Raw dialog box opens.
Sample Data from File. The Import Raw dialog box opens.2. Click Low Density.
3. Select a coordinate system. The Open dialog box opens.
4. Select a data file that you want to import and click Open. You can import a .igs (point-formatted) , .ibl, .vda, or .pts file.