Land Surveyor Forum

Replies

• Land Surveyor

  Mohammad Salem December 3, 2017 at 3:38am

  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?
  • Land Surveyor

    Juan morales > Mohammad Salem December 3, 2017 at 1:44pm

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

      Nitesh Shrestha > Juan morales July 25, 2018 at 8:54am

      Or you can observe your points in angle and distance and when you have the accurate coordinates just calculate all your data from angle and distances. Here in Nepal we always do the survey in angle and distance because why wait for finalizing the traverse  or GPS calculation.
• Vendor

  Ahmed Mohamed November 29, 2017 at 10:09am

  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.
• Student Surveyor

  MUKACHANA TAFARA BOTHWELL November 28, 2017 at 7:44am

  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 
• Land Surveyor

  Nicolas November 27, 2017 at 9:58am

  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. 
• 

  Benjamin J Everett November 24, 2017 at 6:42pm

  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.
• Land Surveyor

  Juan morales November 23, 2017 at 7:14am

  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
• Land Surveyor

  Mohammad Salem November 23, 2017 at 2:16am

  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.
• Land Surveyor

  Mohammad Salem November 23, 2017 at 2:11am

  I mean coordinates as well as elevation(X,Y,Z)