A TN3 file is Topcon's proprietary file format for handling TIN surface data.
- To import a surface, go to Data > Surface > Import/Export and choose From Surface file...
- Find the TN3 file on your USB drive. This will commonly be shown as the D:\ drive or USBHardDisk, depending on the style of data collector you are using.
- Hit the OK button to import the surface file.
- Pocket3D should show the screen at right if the surface imports successfully.
- Importing a surface will automatically make it the active grading surface.