Control problems?

> Any pointers or suggestions?
Check the zone settings. You make no mention of which state plane zones are being used. I suspect somebody used the wrong one. That would cause your base (and your handheld) to believe that it is many miles from where it actually is and introduce large errors into the measured vectors.

To check that the record coords are in the right zone get a lat/long for your site from Google Earth and run it through Corpscon to see if it is the ballpark.

Calling coordinates "WGS COORDINATES" is a red flag.

VERN

Since I have no budget constraints

Well in that case I'm avaiable.

Just need travel time and mileage;-)

There are a few things I would wonder about. If this was a panel project, then has someone flown it? If so, then was a topo developed? Any photogrammetry company I've ever worked with would have been on the phone the first day they were trying match up their photos with the survey data. I can't imagine control busts of +5' not being caught long before any map was generated.

I would break out the level for this project also and do a few checks.

But first-before going to the field I would do a few checks in the office.

If you are using TBC-input the Lat, Long data into a projected file. Set up the file first then input the points as NAD83-forget WGS it really doesn't mean anything. If you match the project setup with the given metadata then the surface coordinates should also check.

Another thing you can do with that is view it on Google earth (open google earth and under the view pull down in TBC click on google earth and the points will appear on the google map). It is a good sanity check to be sure your project is in the correct location and not miles off.

One thing about panels is that they are usually put down using lath, nails, spikes and plastic material; then picked up. It sometimes gets confusing when the panels are removed just which nail or piece of metal was at the center of the panel layout.

"I wouldn't spend another dime of your budget until the author's of the control work are notified and you have recieve an appropriate response."

AMEN to that!!! Sounds like another monkey who can push the on button and has absolutely no idea what they are doing. Its a real disgrace to the profession...

Run some static data on at least 3 or 4 of the control points and process it through OPUS. Compare those coordinates to the "State Plan" and "WGS Ellipsoid" coordinates you were supplied. If they don't match, then the problem is most certainly the data you were given and not what you have collected.

sinc...

No, I meant what I said. And yes, it involves an additional piece of metadata. And yes, we're no longer on NAD83, but can convert our data to NAD83 whenever desired (or vice-versa, such as importing aerial imagery or shapefiles).

But it's the best way I know of to work in, in many situations... With software like Civil 3D, it's easy to key in that metadata, and then you can use Map 3D commands to convert back-and-forth between the LDP and any other system. I know of no way to make C3D "scale up a developed surface" in any sane manner.

Do you do something different?

> Another nit pic, but it's my soap box - there's no such thing as "WGS Coordinates (NAD 83 (92)). You either have WGS 84 coordinates (in one of the 5 different iterations) or you have NAD 83 (1992). NAD 83 and WGS 84 positions will vary by about 1 m each in the horizontal and ellipsoid height.

Another nit pic... Depends on which iterations of WGS and what realizations of NAD83 you are talking about, and also where you're at on the globe. NAD83 realizations have been tending to follow the average location of the North America tectonic plate, whereas the WGS iterations have been modified mostly according to gravitational observations from satellites. So the differences can vary, even though the NAD83 and WGS84 ellipsoids are virtually identical.

Yes You Have Control Problems

Yes you have Control Problems, at many possible levels. I will not even mention coordinate system or SPC Zones.

You say:

"The Survey Control consists of one "GPS Control Point", and seven panel points with an average separation spacing of about 3,500 feet."

Then you go on to say:

"This is a "route" project, approximately 3 miles long with the outlying panel points being about 1500 feet off-site both directions."

I am accustumed to panel points being paired on either side of a project. Given that your first statement allows for 10,500 feet of linear coverage. Deducting the 3,000 feet offsite, that route is a mile and a half not 3 miles. With 8 panel points at most good photo control would only cover 4 overlapping photos.

To cover 3 miles with 8 panel points you are looking at alternating the control side to side. That is weak photo control separate from your observation issues.
Next I want to address "one "GPS Control Point", and seven panel points " as poor in that it provides no redundancy. Were it a small project of 2 overlapping photos where only 4 panel points are needed, I might accept 2 control points. Anything bigger such as your project and the minimum is 3 control points.

The next step is you are trying to prove somebody wrong, hence a higher level of observation is required. Start off with 2 separate static observations of the one control point as well as sufficient static work to establish 2 more control points. Using each of the 3 conrol points you observe all the other points. Your elevation differences should pop out of that test.

"Since I have no budget constraints" ?

Sooner or later your boss has to find the funds to pay you. Do not go forward without now apprising your boss of the elevation inconsistencies and explain to him your plan of attack.

Also remember that even if you are 100% right the other party will scoff at your 1 month experience.

You do not mention your equipment or methods, both of which could be the source of error on your part.

Certain GPS equipment even though appearing exactly alike have differences internally, especially within the antenna, source of many elevation errors. Miss matched equipment can exacerbate said problems. Several years ago some antenna offset issues resulted in differing elevations in different software. Errors that were repeatable by others. Once the equipment was swapped over observed points and the errors doubled could it be confirmed were the problem was. Today there is another source for elevation errors in that some antennas may be set up to process with relative antenna parameters and others with absolute parameters. Generally that antenna data is internal to the processing software.

Paul in PA

Yes You Have Control Problems

Good Post, Paul.

Nate

Yes You Have Control Problems

Yes, very good! You are correct, the panels cover about three miles but the project inside the control is only two. I agree the spacing is too far for a reliable aerial topo, even out here in the wide open spaces of Colorado.

I am using all new equipment Trimble R8 base and rover.

Unfortunately the elevations are not the problem, I could fix that with a level loop. It is the horizontal that is squirrelly.

sinc...

I'm putting together a semi-intelligent answer to your question (above), and will probably start a new thread sometime tonight. I'm pretty much buried right now, so it's taking more time than I had hoped.