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. Error 5013: Activation Failed
  9. Trimble FMX User Guide
  10. Effects of Topsoil Removal and Redistribution on Irrigated Crop Production
  11. Error Code: ERR_FILE_NOT_FOUND
  12. OptiSurface Designer on Apple Computer
  13. Earthworks Conversion Chart (Metric to Imperial) & Planar/OptiSurface Comparison
  14. How to Check Your System Specification
  15. OptiSurface Designer and John Deere's APEX
  16. Designs Generated with OptiSurface Designer
  17. Legend Way Off Screen
  18. Error 5022: System Clock Invalid
  19. Error 9103: Exception Code 8 - Licence Validation Failed
  20. Error R6030: CR7 Not initialized
  21. Error Code 2: OSD Activation Failed
  22. Computer Only Running at 30% of the CPU Capacity
  23. French Manual for OptiSurface Designer
  24. Introduction to OptiSurface Landforming
  25. Using the Lay of the Land to Let Water Drain From A Field
  26. The Benefits by Using OptiSurface Design Software
  27. Draining Surface Water Using OptiSurface Designer
  28. Difference Between OptiSurface Designer Software and the Trimble and Deere Solutions
  29. OptiSurface and Auto-steer GPS: Key to Cost-Effective Erosion Control
  30. 800ha OptiSurfaced for Lateral Move and Drip Irrigation
  31. The Disadvantage of Practicing Multiple Grade Designs
  32. Why You Don't Want Ditches in Your Field...
  33. Connecting Pot Holes to Drains
  34. Dongle Or Licensing System
  35. OptiSurface Designer System Requirements
  36. Hardware List Providing the Best Service and Getting the Most out of OptiSurface Designer
  37. Computer Operating Systems
  38. One or Two Scrapers
  39. Base Station Mobility
  40. Base Unit Distance with GPS Receivers On Scrappers
  41. Getting the Information to the GPS Units on the Scrapers in the Field
  42. Downloading Maps to the Equipment / Machine
  43. Implementing Designs for the Field
  44. What Machine Control Hardware is OptiSurface Designer Compatible With?
  45. Base Station and Line of Sight with the Scrapers
  46. One Base Station with Multiple Scrapers
  47. Training Topics
  48. Two Legends Visible
  49. Auto-Backup Files
  50. Speed Up the Display Graphics (eg Zooming and Panning)

Feedback and Knowledge Base