Why do survey coordinates shift when imported into Google Earth? This was one of the issues that came up recently at the Eastern Surveyors Forum, which we attended in Awka last week. During the event, a surveyor approached us with a problem she had been experiencing.

She explained that after collecting her coordinates in the field, she transferred them into Google Earth, only to find out that the points appeared considerably displaced from their expected positions.

Her concern was understandable, especially when dealing with boundary surveys and possible land disputes.

After examining the issue, we identified that the problem was related to her coordinate reference system and explained how to correct it.

This experience made me realize that other surveyors might be experiencing the same problem. So, if you have ever wondered why your survey coordinates shift when imported into Google Earth and how to correct them, keep reading.

1. WHAT COORDINATE SYSTEM DOES GOOGLE EARTH USE AND WHICH ONE ARE YOU USING?

Google Earth uses the World Geodetic System 1984 (WGS 84) as its geographic reference system. It represents positions using latitude and longitude, usually in decimal degrees.

However, surveyors may collect and process coordinates using other systems, such as Minna-based coordinate systems or UTM projections.

For example, a surveyor working with Nigeria Mid Belt coordinates is not working with the same coordinate system as Google Earth's geographic coordinates.

Before transferring such data into Google Earth, the coordinates must be properly transformed into WGS 84.

2. WHAT CAUSES COORDINATES TO SHIFT?

Several factors can cause survey points to appear in the wrong location.

A. Datum Differences

A datum provides the reference framework for positioning points on the Earth.

Many Nigerian surveying and mapping workflows use coordinate reference systems based on the Minna Datum, while Google Earth uses WGS 84 for geographic positioning. If coordinates referenced to Minna are interpreted as WGS 84 without the appropriate transformation, the points may appear displaced.

B. Wrong UTM Zone

Nigeria falls across UTM Zones 31N, 32N and 33N.

Using an incorrect UTM zone during data collection or processing can result in wrongly positioned coordinates.

Always confirm that the selected zone is appropriate for your project location.

C. Incorrect CRS (Coordinate Reference System) Settings

Your GNSS receiver, controller, and processing software must use the correct coordinate reference system.

If your receiver collects data in one system but your processing software interprets it using another, the resulting positions may be incorrect.

D. Incorrect Coordinate Transformation

There is a difference between assigning a coordinate reference system and transforming coordinates.

Assigning a CRS tells the software what system the existing coordinates already use. Transforming coordinates converts them from one system into another.

Simply changing the CRS label from Minna to WGS 84 does not convert the coordinate values. The correct transformation must be applied.

E. Incorrect Export Settings

Google Earth's KML format expects coordinates in Longitude, Latitude, and Altitude order.

If latitude and longitude are interchanged, or Easting and Northing values are exported without conversion, the points will not appear correctly.

3. HOW CAN YOU FIX THE PROBLEM?

If your survey coordinates shift when imported into Google Earth, check the following:

Check your GNSS settings: Confirm the datum, projection, UTM zone, and units used during data collection.
Identify your source CRS: Know the exact coordinate reference system in which your original coordinates were collected.
Apply the correct transformation: If your data is in a Minna-based system, transform it appropriately into WGS 84 before exporting to Google Earth. Ensure that the transformation selected is suitable for your project location and required accuracy.
Check your export settings: Ensure that your software exports the coordinates in the correct geographic format.
Verify the results: After transforming your coordinates, compare the results with known control points or reliable reference data to confirm that they are in the correct positions.

Always check the accuracy of the transformation method being used, particularly for cadastral and boundary surveys. Where high precision is required, use an appropriate authoritative transformation and verify the results against reliable survey control.

4. CAN I CONFIGURE MY GNSS DATA LOGGER TO USE WGS 84?

Yes. Many modern GNSS receivers allow surveyors to select WGS 84 as a coordinate reference system. If you want to compare your field coordinates with Google Earth, you can configure your data logger to output WGS 84 geographic coordinates, provided your equipment supports this.

However, this does not mean WGS 84 should be used for every survey project.

The best practice is:

For fieldwork: Use the appropriate coordinate reference system required for your survey project.
For Google Earth comparison: Export or transform a copy of your coordinates into WGS 84 geographic coordinates.

Some GNSS controllers, like SinoGNSS systems, also allow additional coordinate outputs. This means you can retain your project's working coordinate system while generating WGS 84 coordinates for mapping and comparison. Confirm the available options on your particular receiver and controller software.

Interested in purchasing a SinoGNSS receiver? Contact OTIC Geosystems by phone (+2347061769934) or WhatsApp Constance for enquiries and assistance.

WHY DOES THIS MATTER IN BOUNDARY SURVEYS?

Imagine completing a boundary survey only to discover that your coordinates appear on a neighbouring property when imported into Google Earth. This can create confusion, particularly when investigating boundary disagreements or possible encroachment.

Your client or the other party involved in a dispute may ask you to plot the points on Google Earth because it is the platform they are familiar with. It could be embarrassing when your points appear nowhere close to their expected positions, even when your field measurements are correct.

This is why surveyors must understand how to transform coordinates between different reference systems properly.

Always verify your coordinates before presenting them. Remember, Google Earth is useful for visualising survey locations, but its satellite imagery should not be used as the sole basis for determining property boundaries.

Conclusion

The next time your survey coordinates shift when you import them into Google Earth, don't immediately assume your GNSS receiver is faulty.

Check your datum, projection, UTM zone, and coordinate transformation settings.

Sometimes, the problem is not with the measurements you have taken but with how your coordinates are being interpreted.

Remember: Correct measurements must also have the correct coordinate reference system.

Why Do Survey Coordinates Shift When Imported into Google Earth? Causes and How to Fix Them

Why Do Survey Coordinates Shift When Imported into Google Earth? Causes and How to Fix Them