Land Surveyor Forum

Replies

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  謝鑫宏 February 23, 2015 at 9:21pm

  Not about datum and scale. My company use 2 kind method.

  1st

  1. Go out into the field collect data and return to the office

  2. Download the data into the computer and then rotate the collected data to match "local coordinate"

  3.Go back out into the field to do "site calibraton" at controller.

  4.Collect more data or set come property corners

  2nd

  1. Go out into the field collect data and return to the office

  2. Download the data into the computer and then rotate the collected data to match "local coordinate"

  3.Use the data surveyed to do "site calibraton" at office on the controller.

  4.Go back out into the field to Collect more data or set come property corners.

  Keep all datas in controller. As amire said, It's not a total station. There will be 2 coordinate data in 1 point after you do calibration.

  It is depends on the amount of control points you surveyed. If you got enough control point data then just calibrated in office will be enough.
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  Arie Lise, OLS, OLIP, Dipl.T. February 23, 2015 at 12:42pm

  Wow, using GPS without a scale factor.  Better asks your boss if he knows what a Geoid is.  Maybe its time for him to retire.  You guys aren't by any chance finding your total station measures a little longer than your GPS are you?
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    David Chandler > Arie Lise, OLS, OLIP, Dipl.T. February 24, 2015 at 9:53am

    If we work in state plane then of course the measures are different. If we set the GPS to ground measure the distances seem to check perty good against the total station if and when we compare.

    I tried to explain to the boss, that the scaling if any is minimal. I mean really you tie into a bunch of points and go back two days later and check into the same points how much scaling if any could there possibly be???  And FYI im with you guys ive read the book and know what needs to be done but the man that signs my paychecks says no, then I have to work around it I guess... His son is set to take over the buisness in the next few years, and he sides with me on this one. LOL
  • Seeking Employment

    amir shahbaz > Arie Lise, OLS, OLIP, Dipl.T. February 23, 2015 at 12:57pm

    he think Gps works as a total station ?
• Seeking Employment

  amir shahbaz February 23, 2015 at 12:27pm

  your detam should be UTM WGS -84 in your software which you are using for data collection .it will automatically give accurate positions .that's it ,ask your boss to believe in modern technologies and work better and easy

  thanks 
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  Donald E Robinson, PLS, CFS February 20, 2015 at 9:26pm

  I believe you have it backwards. I think you should rotate the Local data to match the data you recorded in the field.
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    Arie Lise, OLS, OLIP, Dipl.T. > Donald E Robinson, PLS, CFS February 21, 2015 at 8:06am

    Due to statutory changes recently we have had to adapt to putting "grid" (UTM) bearings on our plans.

    I always preferred showing the astronomic bearings - because if something has been done for 300 years why change it? Right?

    The astronomic bearing can change based on what someone else has accepted over time or, it really just has become a local convention carried forward that sometimes can be out by quite a bit.

    Also there is a tendency to use a side line as a reference and then stretch the the road bearing tolerances (usually the nice even reference like N45d00'00"W) to match the 300 year old bearing so that it can be said you agree to way back when.

    I found when I started using grid bearings they compare quite well to other grid bearings (so less work comparing), and they shouldn't change with time or convention.

    I use a red pencil to alter each of comparison plans North arrows with the grid adjustment for future reference and provide a chart on the face of my new plan showing the adjustment angles.  I show all my comparisons in grid so that you are comparing apples to apples, the drawing looks neater, and it says where you agree and disagree with previous quite plainly (and is also a statutory requirement here).

    It is just like switching from Imperial to Metric measuring units, once you go, you gotta go all the way.

    -Arie Lise, OLS, OLIP
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      David Chandler > Arie Lise, OLS, OLIP, Dipl.T. February 23, 2015 at 9:49am

      I have read the part in the manual about calibrating but the company owner says "no way" because in the instructions it talks about SCALING as well as rotating. I should also mention that my boss is very set in the "old way of doing things" its very hard to get him to try new things. I guess as far as that goes we just need to keep doing what we have been and hope we dont create any errors that cost us. Thank you for the input everybody....
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  Timothy Lemay Blackmon, PSM February 20, 2015 at 8:48pm

  Your software in Data Collector allows you to rotate to "local grid" or equivalent. Instructions should be in your operators manual. I haven't used TDS (now trimble) software in years but all field software is basically same. I would respectfully submit that you are thinking a tad backwards. I would rotate the SURVEY even if supplied by others on DAY 1 to State Plane Coordinates and stay with them. Why would you NOT do this? It makes everything much easier in the long run, hence your problem. You are introducing so much opportunity for error every time you rotate back and forth....really bad idea.........

  If I break out the GPS on ANY job, the finished product is ALWAYS based on State Plane Coordinates and I simply label the deed calls as I would on any survey. You give it to Engineer/Architect, they design off your survey and your stakeout calcs are later automatically in State Plane coordinates. Seems like your desire to hold on to the old deed bearings is the "problem" Just sayin'. Good luck with it, Timothy L. Blackmon, PSM
  • Land Surveyor

    J. Anthony Cavell > Timothy Lemay Blackmon, PSM February 20, 2015 at 9:29pm

    Localizing (or calibrating) will do the trick.

    However, even without learning that you might be able to save your job by making backups of the data from your field work before rotation and translation.

    (Also record the rotation and translation statistics in case you want to reverse the process.)

    You will have your field data backed up and your transformed data in your computer.

    That is a simplistic remedy but not very sophisticated nor a cure. The better solution is to localize your data to the project datum.

    Best wishes,

    Tony

    P.S. If there is not project datum, use a standard datum and projection such as state plane or a local projection.