2019 Release 0: March, 2019
TPC’s Site Calibration is pretty amazing.
Use any existing calibration as the Site Calibration or create a new one, and TPC will automatically calibrate GNSS data to your survey.
GNSS points always retain their original geodetic positions, but take on calibrated coordinates, so they plot right over the top of your survey and work for all COGO computations like offsets and inverses.
In the example here, we identified some lot corners in Google Earth, imported them into TPC, created a calibration to tie Google Earth to our survey then selected it as our Site Calibration.
Now we can work seamlessly between TPC and Google earth to
- Plot your local site data directly in Google Earth
- Create points and figures in Google Earth and plot/use them in your local site survey
When you calibrate a photo to your survey, pick as many point pairs as you can find on the photo, then let TPC’s Least Squares calibration routine create the best fit for you.
TPC even generates a world file for the photo, so that when you insert it into the next drawing, it comes in at its calibrated position – automatically.
We get a lot of questions about how to use background photos in a drawing, and getting the photo to line up just right with the survey used to be a bit tricky.
Just pick a series of photo points then those same points in the survey, or pick point pairs like the three shown here and TPC will rock the photo right into place.
How many times have to gotten a CAD file that didn’t match your survey?
- Like the one state plane survey you just sent off to the lighting engineers, only to get the design back at local coordinates 0,0?
- Like the architect who uses 4 feet per inch
- Or like the drawing shown below, where the XRef is close, but not quite.
- It happens all the time.
We inserted this XRef into a drawing only to find that it doesn’t quite fit our survey. So we calibrate it. We show the first two point pairs here, so you can see how we snap to the same end of line in the XRef, then the drawing.
Calibrate Xref First Two Point Pairs
A few more clicks for a total of four point pairs, or as many as you prefer, and the XRef is calibrated to our survey. And because TPC uses a Least Squares best-fit routine to compute the calibration, you can look at the residuals to see how good the fit really is.
And one you’ve established the relationship between a CAD file and your survey, you can share data between between them using that calibration.
Apply a reverse calibration when writing a new CAD file and it ends up in CAD coordinate system – automatically.
Of course you can have TPC generate State Plane or UTM coordinates based on a Coordinate Reference System, but what about working with a local site survey. You know, where everything is in ground distance at 5000/5000?
With calibrations, it’s easy.
- Calibrate GNSS to local site
- Plot/use GNSS data in your survey’s local site coordinate system
- Reverse calibrate to send local site data out to GNSS for stakeout
- Happens automatically with new Site Calibration
In the example shown here, we occupied each monument with GNSS (400, 401, etc) then inserted the local site point (400:1, 401:1, etc) as a side shot. That all TPC needed to create the calibration. Of course there are other ways to use traverses to generate a calibration. Just choose the one that works for you.
Once we apply the calibration, either directly to the GNSS points or via a Site Calibration, the GNSS points get calibrated to their Local Site coordinates.
It’s all pretty seamless and easy to use.
Calibrate Total Station
Now you can calibrate total station data based on assumed coordinates and rock it right onto your survey.
Starting with assumed coordinates
How many times have you started a survey using assumed coordinate system in the field?
In the example shown here, we just assumed coordinates for our occupied point and backsight. So as you can see, it’s close, but not quite.
So now we want to rock it onto the two lots shown in white.
It’s easy to do because in the field, we tied a number of the existing lot corners that we found. This gives TPC everything it needs to easily create a calibration using Least Squares best fit for all the tied lot corners.
Sending data back to your data collector
The choice is yours.
- Send a new job back to the data collector using the survey’s coordinates
- Or reverse calibrate to send any survey points back to the data collector in its assumed coordinate system for stakeout
It’s really the best of both worlds.
Pick a project location from any existing point or compute an average. Then use it to
- compute the combined factor for the survey
- scale points about it for grid<=>ground conversion
- update available Distance types to use it’s elevation
Having a project location documents how you came up with your combined factor and computed ground distances. It’s an easy way to set up your project location one time and then let TPC do the heavy lifting.
Here, we’re converting the coordinates in our Sec 14 Corner Moves traverse from Grid to Ground for stakeout. We’re using the Project Location point, AVG, computed from the new Average Point routine, to establish both the base point and the scale factor. Wow, that’s pretty easy.
The new Average Point COGO routine computes an average position from TPC’s What list (any points, traverse, drawing objects, etc).
In the example here, we’ve selected the each portion of a PLSS section and created an average position. We then used the average position to compute the combined factor for the survey.
Saved as a Traverse
The average point computation can be saved as a traverse, with all the points included in the computation inserted as side shots from the computed average. You can then open the traverse anytime in the future to see exactly how the average point was created.
Assign the computed average to the survey’s Project Location
The average point you compute can easily be assigned to the survey’s Project Location. TPC will use it compute the Z (elevation) factor and the Grid factor for that location and even combine them to compute the survey’s Combined factor.
You can also use the updated project location for grid<=>ground conversions.
The new View[+] plots any COGO solution over the top of the current drawing.
In the example shown here, we’ve plotted the computed average point (AVG) with a side shot to each of the points contributing to the computed average. This is a great way to see how the average fits into the survey overall.
Press the View button to create a new drawing with just the solution (same as always)