Workflow in Trimble Access

You can translate base coordinates after the fact in the Point Manager, but it's better to do that in TBC when post-processing. Depending on observation methodology, some points may not shift with the base in Access.

If I am running the same job for a few days, unless it is critical, I don't typically change the base location. Part of this is that I want to wait for rapid orbits to become available before post-processing, and part of this is just to keep everything simple and relative for the time being.

When setting up with an autonomous base position, I also tag the point ID with the suffix "_AUTON" so that it is clear where that point came from. If I correct it in the office and then go back to the field, I will create a new point, and drop the suffix so I know it is a post-processed position. I will also export the CSV and DXF of corrected data so far, and then just link to those files in my new job so I can see what I have done already.

Long story short, my recommendation is to add a new point with the corrected position rather than edit an existing base location.

You have to be careful changing the base point. TBC allows you to send the base file directly to OPUS and when you get the corrected location you can download and shift the auto point over, then hit recalc and the located points will move with the base. However, you must understand that any calculated points will not shift and any stakeout points will not shift. There is an edit function under project explorer that allows you to edit as staked points and allows them to shift.

Also under project explorer you can edit the base point and change the auto point to the OPUS location. Or you can imput the OPUS location and simply move the auto base point to it and then do the recalc. Just be sure the points do shift correctly, I normally write it all down, check it with what's in the DC against the TBC file and when I'm very sure it's all good delete the DC file. Then for the next days work upload a corrected DC file.?ÿ

Thanks for your replies.

I have seen how to merge points in TBC. I can merge the auto base to its corrected OPUS position and have all rtk shots move.

After I do this, I just output a job file to the DC and work in that?

Thanks again for your help in this.

Posted by: @byanez

After I do this, I just output a job file to the DC and work in that?

That will work just fine, just be aware that you will have all those points embedded as "normal" class, so it might be a bit more difficult to differentiate between what you are observing in the current job versus earlier data.

My preference is to have a JXL file with only the adjusted control embedded, use that as the template for any new jobs, and then link to any other files that I need to see, whether it's linework or points, or DTMs, alignments, etc. So in your case I would also have a CSV with the topo points, and linework as a DXF. I just like to be able to turn off everything but my current job data at times, but that's just me. YMMV.

@rover83?ÿ

I will have to figure out the linking of files part.

So, far I have only been talking about points in SPCS or pseudo-SPCS. When is the best point to do the grid-to-ground corrections, which I am assuming are done in Local Site Settings and Site Calibration? If I do the grid-to-ground corrections in TBC and output a new job file, when I set up in the field on ground coordinates, will those still be linked to their SPCS positions?

I would have all the parameters set up in TBC before going to the field. Normally I will set up a TBC job as a process of setting up a client and job. Once it's set up I don't change it.?ÿ

@byanez?ÿ

The real link to all XYZ coordinates will be the Lat, Long, hgt coordinates, those can be sent to any file and recomputed to whatever XYZ you want.?ÿ

@byanez?ÿ

To apply a combined scale factor for grid-to-ground, Local Site Settings in TBC is what you are looking for. There are a variety of ways to do it (scale from origin/scale from defined point, truncate/not truncate), but the dialog is pretty user-friendly.

You can do it in Access in the field as well. You can start a job in a plane coordinate system, then start your base with a here position, and then go back into the job coordinate system settings and select "Ground (calculated scale factor)" and pick your base point for the scale factor. Or, if you are connected to a receiver when you create your job, you can simply select "Here" at the bottom of the screen when you go into the ground section of your coordinate system settings, and it will pull the autonomous position to calc the CSF.

For me this was always good enough for fieldwork, but I would typically refine everything later on during post-processing. Sometimes that initial base location is not the best place to pull a CSF from.

Site Calibration = "localization", for transforming GNSS vectors down to a local coordinate system with no pre-established geodetic relationship. Really shouldn't be used unless you are trying to work with GNSS on a completely assumed local coordinate system.

Whichever method you use, when a JXL or JOB file is exported, the coordinate system parameters go with it. This is why I really like using them as templates with only control points embedded - it is a blank slate with all the critical data in there, and then I can decide what, if anything, I want to link for a particular task.

When you do export to JXL/JOB, just be aware that you can select "Grid", "Global" or "Local" as the Output System. If the end field user does any coordinate system manipulation after the fact (pretty rare), it can impact how Access treats the points.