Survey Pro 5.6.2 won't calibrate

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GNSS & Geodesy

Last Post by MSJ-Surveyor 11 years ago

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MSJ-Surveyor

(@msj-surveyor)

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I'm trying to calibrate to a file a firm sent me to stake some road centerline. They tell me the control point coordinates are a modified state plane where the initial point is a true state plane coordinate, but the rest are scaled such that ground distances are used. After shooting the control points the calibration routine returns acceptable results, no more than 0.04' in the horizontal and 0.03' in the vertical. I have three points which have are good horizontal and vertical, but the calibration says "Horiz. blunders detected!" and "too few points to check vert." When I check the "Finish" on the calibration routine it does not do anything, just goes back to the projection screen. These are the only three points I have to go from. Anyone had any such problems?

Posted : October 10, 2015 5:09 pm

cwlawley

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More than likely you just need to go back and hit a few more points. With Survey Pro 5,xx you are required to have four good points, without blunders for a good vertical calibration and three for a good horizontal calibration. If you have blunders and told the dc not to use that particular point for horizontal then it wouldn't count to those good points. Also, in the table of points, make sure you have "yes" on for using it under v and h. Sometimes guys accidently click them off without knowing.

Posted : October 10, 2015 5:24 pm

callen

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I have had good luck choosing 1 point as vertical if the site is fairly flat. Might try that before setting out extra points. Doing this you have to be SURE to check known elevations at the extremes of the job. Haven't done it in 5.6.2, but one version down I believ was the last one like that.

Is it worth just trying to use actual spc in DC and and a geoid, then set on one known in middle? My experience has been inexperienced crew calibrates to spc and the scale factor/rotation diff is essentially the same as spc. Again, I'd don't know your terrain, my spc world is pretty flat compared to some.

Posted : October 11, 2015 10:39 am

thebionicman

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If you have full meta data (and it sounds like you do) just make a new projection.
For the scale factor use 1/CAF ÌÑ Zone reduction factor. Use the same central meridian and latitude of origin. You can compute the new false northing and easting or simply shift them until the base point matches SPC.
All of this assumes TM projection. It's similar in lambert. The advantage is you maintain real geographic coordinates and the geoid model. No calibration is required. You set up, check in and go to work.

Posted : October 11, 2015 10:52 am

MightyMoe

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I would do what thebionicman says.

I would further say that if you are in trimble it allows you to apply the scale factor to the initial point so everything is on the same page.

If you HAVE to calibrate because your software won't allow anything else (it's hard to believe but I've seen that very thing), I would do it in the office with enough points. There is no need to go to the field to calibrate this kind of system.

This gives you to option to use as many points as you like and check them to the qeoid model, see how the calibration checks, in my area it would check awful.

Posted : October 11, 2015 3:41 pm