Is GPS Accurate Compared to Laser?


My hope is that the GPS vertical accuracy is going to get to +/- 30 mm or less but that is pushing the normal GPS vertical accuracy envelope. Using normal GPS survey techniques and then checking the vertical accuracy using optical surveying on control points showed up maximum errors of up to +/- 60 mm here. That was not the accuracy from machine control while moving but GPS surveying involving stopping on the control spot for say around 1 minute with the survey gear then comparing that to optical (dumpy level ) checks. That is a concern for me. What are you finding for vertical accuracy from your experience?


GNSS RTK GPS with a base station within 1km of the field, we think is probably within +/- 25mm most of the time (66% of the time, 1 standard deviation) and +/- 50mm (95% of the time, 2 standard deviations).  This means the operator should be on the ball and be aware of the shifts in accuracy.

The critical accuracy is probably during the final trimming operation and the accuracy is better that those given above.  The more critical accuracy is the error that occurs over a two minute period which is the time it typically takes to do a final trim from one end of the field to the other. 

In this case, the accuracy could be 4x better than what is listed above and in that situation it is very usable and probably better than laser at >300m from the laser transmitter.


  1. Accuracy of RTK and RTX GPS
  2. Export To Field Level .gps File From UTM Coordinate System
  3. How Often Does The Earthworks Need To Be Done?
  4. GPS Accuracy Affected by Solar Activities
  5. Is OptiSurface Compatible with John Deere?
  6. Is GPS Accurate Compared to Laser?
  7. Is Cellular RTK Networks Accurate Enough for GPS Landforming?
  8. Trimble FMX User Guide
  9. Effects of Topsoil Removal and Redistribution on Irrigated Crop Production
  10. OptiSurface Designer on Apple Computer
  11. Earthworks Conversion Chart (Metric to Imperial) & Planar/OptiSurface Comparison
  12. How to Check Your System Specification
  13. OptiSurface Designer and John Deere's APEX
  14. Designs Generated with OptiSurface Designer
  15. Legend Way Off Screen
  16. Computer Only Running at 30% of the CPU Capacity
  17. French Manual for OptiSurface Designer
  18. Introduction to OptiSurface Landforming
  19. Using the Lay of the Land to Let Water Drain From A Field
  20. The Benefits by Using OptiSurface Design Software
  21. Draining Surface Water Using OptiSurface Designer
  22. Difference Between OptiSurface Designer Software and the Trimble and Deere Solutions
  23. OptiSurface and Auto-steer GPS: Key to Cost-Effective Erosion Control
  24. 800ha OptiSurfaced for Lateral Move and Drip Irrigation
  25. The Disadvantage of Practicing Multiple Grade Designs
  26. Why You Don't Want Ditches in Your Field...
  27. Connecting Pot Holes to Drains
  28. Dongle Or Licensing System
  29. OptiSurface Designer System Requirements
  30. Hardware List Providing the Best Service and Getting the Most out of OptiSurface Designer
  31. Computer Operating Systems
  32. One or Two Scrapers
  33. Base Station Mobility
  34. Base Unit Distance with GPS Receivers On Scrappers
  35. Getting the Information to the GPS Units on the Scrapers in the Field
  36. Downloading Maps to the Equipment / Machine
  37. Implementing Designs for the Field
  38. What Machine Control Hardware is OptiSurface Designer Compatible With?
  39. Base Station and Line of Sight with the Scrapers
  40. One Base Station with Multiple Scrapers
  41. Training Topics
  42. Two Legends Visible
  43. Auto-Backup Files
  44. Speed Up the Display Graphics (eg Zooming and Panning)

Feedback and Knowledge Base