Hi, every body I am using Garmin handy GPS with low accuracy to establish BMs but there is needed high accuracy for this survey, but i am not able for now to have a high accuracy GPS due to time shortage, and there is plane to buy a high accuracy GPS after some days later (that time we will do some of our survey on the site), so is there a way to change my topographic surveyed coordinates with new measured coordinates?


This Content Originally Published by a land surveyor to Land Surveyors United Network

Views: 514

See Your Saved Posts Timeline

☇ Reply to this

Replies to This Discussion

Just Z....or X and Y as well?
Yes … re-observe all your BMs with the high-accuracy gear. That’s the ONLY way.
Yes, it is possible, just not desirable. The more points you have the worse it gets. If you are planning to change the coordinates DO NOT send them to anyone. That is just asking for problems and possibly law suits. Consider renting a precision instrument to cover you until you can purchase. NEVER scrimp on control.
I mean coordinates as well as elevation(X,Y,Z)
If any one knows how to change it, it would be great if he/she fully describe the method(s), I know there is a way in liscad software but in closed triangulation and i am not sure for an open one.

Almost 5 meters in position and 10 meters in height. Not good for changes that you are asking. Rent a profesional equipment from the very beginning

Nav and Mapping grade GPS is out of the question. It’s an order of accuracy issue. You can’t maintain the required tolerance for the site with that equipment. Do what you may, but you’ll be doing the work over again with Survey grade equipment.

Like most replied here I wouldn't even attempt to collect any info with the low grade GPS. The issue being is your low accuracy device will not have relative info within itself. So the issue being is when you localize into your BM's with the survey grade GPS you will find that none of your BM's will check. 

you will have to redo the survey since if you use the ones you took with the garmins the coordinates will still be inaccurate as per the required 

If your question is about coordinate transformation between the Garmin-observed coordinate set and the survey-grade set by applying some sort of shift and/or rotation, the answer is not possible. The noise level (inaccuracy) of the Garmin-observed set will overshadow any possible correlation between the two coordinate sets. The low-accuracy set will help you plan for your BM establishing session.
If your question, on the other hand, is about exploring possible correlation of some sort between the two sets of coordinates, you might be able to do some stochastic modeling which is far beyond this discussion forum! This is similar to transforming between NAD27 and NAD83, where a simple shift and rotation is not possible because of the lack of accuracy with the NAD27 datum definition itself.
Hope this helps.
Thanks friends for your suggestions but...
my question is that is there a way if you survey a land site with incorrect (ex. x100,y200,z300) coordinates and then observe only BMs with high accuracy coordinate and change all surveyed data with new observed BMs coordinates?

of course, you can do it, but  for example if you use a Helmert transformation the residuals will be out away of scale 


Where Thousands of Professional Land Surveyors, Students of Surveying and Educators are United through Collaborative Knowledge and Purpose.

Land Surveyors Forum

modern method of stereo model

Started by shree ram bhandari in Surveying Documents. Last reply by ⚡Survenator⌁ 13 hours ago. 1 Reply

Survey Abstract Coordinates

Started by John J Rodriquez in Surveying Best Practices. Last reply by Donald E Robinson, PLS, CFS yesterday. 16 Replies

Control surveying problem

Started by shree ram bhandari in Land Surveying Jobs. Last reply by Billy Brooks on Saturday. 11 Replies

Magnetic North Update

Started by Billy Brooks in Surveying Best Practices. Last reply by Billy Brooks Feb 6. 2 Replies


Started by Lalith Senanayake in Surveying Related Links. Last reply by shree ram bhandari Feb 12. 4 Replies

Job Quotation

Started by Nitesh Shrestha in Land Surveying Jobs. Last reply by Nitesh Shrestha Jan 21. 3 Replies

Survey under tree canopy

Started by Massimo in Surveying Best Practices. Last reply by Maurice Heter on Saturday. 7 Replies

Mean Sea Level (MSL)

Started by Chuck Turlington in Geospatial Industry Types. Last reply by Kim Noblitt Jan 17. 6 Replies

Surface pro

Started by Malik in Surveying Field Tips and Tricks. Last reply by Kevin D. Allen Jan 7. 5 Replies


Started by Mthulisi Mloyi in Professional Advice for New Surveyors. Last reply by ⚡Survenator⌁ Jan 4. 2 Replies

Tools,Apps and Quick Guides


Help With Survey Equipment

Social Support For Equipment

Surveying Video Categories

Surveying Photo Categories

United States Hub Forums

International Surveyor Hub Forums

Resources for Company Owners

Land Surveyor Social Media

Surveyor Resources Collections

Getting Started & Newsletter

Featured Land Surveyor Hubs

Surveyor Birthdays

© 2019   © Created by Land Surveyors United   Powered by

Badges  |  Contact LSU  |  Privacy Policy  |  Terms of Service

Site Explorer