OPUS ground check

How far apart are the stations? The UTM scale factor can vary pretty rapidly. Why enter a combined factor, won't Survey Pro 5.x handle all of that? In Access all you do is specify the UTM zone and underlying datum, you don't calibrate or enter a scale factor; I thought Trimble had got Survey Pro up to speed on the geodetic side?

First, confirm that your US Feet/ Int'l. Feet settings are in agreement everywhere. If you are using feet anywhere in this.

If you are setting your job up as a UTM job you should not also be supplying a CSF at the dc. It should deal with that math for you. Perhaps you are double dipping at the scale factors?

If you set up a job in UTM, and set your base on a point in your UTM, you shouldn't have a need to calibrate.

lanceboyle93101, post: 339919, member: 2061 wrote: A non-infrastructure job, but has me concerned.

Static obs. on 3 new points processed thru OPUS static. Terrific position errors: Horz. on order of mm. Vert on order of 1.5cm.

Load UTM coords in Ranger.
Specify the zone and CombFactor, as ave. of the 3 estb. stations. (running SurveyPro5.x) ave. CF=1.00028228 Ave. ortho 1645.369 m.
[hl]Set base at random [/hl], & rove to the 3 stations; solve calib. WTF! position errors on order of .5m

Ground baselines/Grid baselines do not ratio to the CF value. The 3 baseline ratios vary. (baselines from 0.5km to 1.1km)

Suspect a scale issue, by manually inserting a CF when setting the UTM zone, but variability of the baseline ratios confounds me.
Ideas gurus?

I know the manufacturers loved to tout the above "simple" workflow, but the "base at random then calibrate" idea introduces tons of issues. If you want to survey on UTM, then survey on UTM, no calibration needed.

If you want to survey on some local system (but with the ability to transform to UTM), then add more OPUS points so that you can at least set your base on a point of known position.

thanks for reply amigos.
Yes, I understand if in mapping zone, no need to calibrate. The specified zone is all it needs.

Survey Pro directs user to rove to a known pt anyway. Regardless, shouldn't meas to the 3 known pts be much tighter that .5 m ??? I trust the OPUS values because I've has such good results in past.

I was thinking I'm 'double-dipping' the scale factor; that is specifying a CF manually, at same time the UTM CF is automatically applied by SurveyPRo, so both factors are being used.

BTW, working in meters. No US ft/Intl Ft. issues

lanceboyle93101, post: 339931, member: 2061 wrote: thanks for reply amigos.
Yes, I understand if in mapping zone, no need to calibrate. The specified zone is all it needs.

Survey Pro directs user to [hl]rove to a known pt[/hl] anyway. Regardless, shouldn't meas to the 3 known pts be much tighter that .5 m ??? I trust the OPUS values because I've has such good results in past.

I was thinking I'm [hl]'double-dipping' the scale factor[/hl]; that is specifying a CF manually, at same time the UTM CF is automatically applied by SurveyPRo, so both factors are being used.

BTW, working in meters. No US ft/Intl Ft. issues

Yes, I think your problem probably is that you're mis-applying a scale factor. This is made difficult to detect by the fact that you set up on a random point and then did a calibration.

I recommend

1. Set your SurveyPro job to be in UTM with Geoid12B. As in UTM-period-not scale factors or other juju.
2. Set your base on a known (OPUS) point, with a carefully entered H.I.
3. Stake out to your other two points and hit them nuts on.
4. Miller time.

Try flipping the CAF. Simply take 1/CF. If that solves it your issue is one of a few things.

lanceboyle93101, post: 339919, member: 2061 wrote: A non-infrastructure job, but has me concerned.

Static obs. on 3 new points processed thru OPUS static. Terrific position errors: Horz. on order of mm. Vert on order of 1.5cm.

Load UTM coords in Ranger.
Specify the zone and CombFactor, as ave. of the 3 estb. stations. (running SurveyPro5.x) ave. CF=1.00028228 Ave. ortho 1645.369 m.
Set base at random , & rove to the 3 stations; solve calib. WTF! position errors on order of .5m

Ground baselines/Grid baselines do not ratio to the CF value. The 3 baseline ratios vary. (baselines from 0.5km to 1.1km)

Suspect a scale issue, by manually inserting a CF when setting the UTM zone, but variability of the baseline ratios confounds me.
Ideas gurus?

I read this post and I'm frankly flabbergasted.

Three points are set and OPUS values are established.

Then when it's time to work, instead of setting on the static points a random point is occupied and the three points are RTK'd then an attempted CALIABRATION is done................

Why degrade a projection by layering a calibration over it and worse yet using RTK,,,,,,,,,,I know this is taught, but it's unacceptable in my company.

The only reason to do it is because of old, old, old control like a NAD27 job that can't be updated.

You have new OPUS data and you aren't going to use it. Think what an RTK calibration is doing, you have UTM, apply the CF, no big deal, why throw all that out and calibrate, you lose your Geoid, you lose your projection. Makes no sense to me, and you can see it made a mess anyway, take just a tiny bit more time and get on the established system.