To vertically offset the contour lines in Global Mapper:
1. Open the contour lines file in Global Mapper.
2. From the Menu, File > Export > Export Vector Format > select XYZ (Simple ASCII) Text File.
3. On the ASCII Export Options, select Export Elevations for Each Vertex box.
4. Open a new Global Mapper project (Workspace).
5. On the Menu click File > Open Generic ASCII Text File(s).
6. On the window that opens, select the file previously exported (step 3).
7. On the Generic ASCII Text File Import Options window that opens, click Select Coordinate Offset/Scale and select the Point, Line, and Area Feature option.
8. On the Select Offset/Scale window, select the Z vertical offset value (in this example 30 meters) and click OK.
The contour lines now have been vertically offset. To change their labels to the new altitude values:
1. On the Menu click Tools > Control Center.
2. Right click on the contour lines layer.
3. Click CALC ATTR - Calculate/Copy Attribute value.
4. On the Attribute Calculation Setup, type the new attribute name.
5. On the Attribute Calculation Setup, select Source Attribute: Elevation.
6. On the Attribute Calculation Setup, select Operation: Add.
7. On the Attribute Calculation Setup, type the offset value in the Used Fixed Value field (in this example offset value is 30 meters).
8. Click Calculate.
9. On the Menu click Tools > Control Center.
10. Select the contour lines layer and click Options...
11. On the Vector Options window, select the Use Selected Attribute Value for Name option and from the drop down list select the new attribute previously created (step 4).
12. Select the Display Labels for Layer if any Shown option.
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