BASE SHIFT

Glen Yasharian

New Member
I know there have been posts regarding base shift, but, I can't find any specific to my question. Assuming that the possible bug in the 'base shift' function on the LS has been resolved, is it possible to use the average of several shots for the point that you want to shift to? Whenever I use this to shift an atonomous session over to established coordinates, it only allows me to RTK one point for the shift. I suspect that this is assumed only to be a temporary measure until the base file and RTK shots are DEPOS'd. However, there are some circumstances where I would like to hold one legacy coordinate and adjust the new work to it, such as when extending control for the same project ; I would just feel better if I could average several RTK shots to make the translation (and without doing a more complicated localization).
 

Adam

Well-Known Member
5PLS
Have you tried using mlocal from the processed points screen? Its the icon that has two parralel planes on top of each other.
 

Glen Yasharian

New Member
I should have mentioned that the 'legacy' coordinates and the 'new' coordinates are both in State Plane; neither is a 5000/5000 local system. I'm working in mountainous, wooded terrain with very few open sites for the base. So, I set a point as far from the first base as I could, then leap-frogged to an open site beyond it and set up the base on a second point (autonomous). I took several shots on the 'in-between' station and averaged them. There is only about 0.06' difference between the coordinates for the common point after I DEPOS'd the second base setup, but, I would rather have shot the whole project from one base setup to prevent this error from increasing, but, that won't be possible ( it will probably take a total of three base locations to cover the whole site.) I can do a simple translation in the office. The M-local seems to be a 1 point transformation. Looking at the video on this, it appears that it was intended to adjust GPS coordinates back to a local '5000,5000' ground system.
 

Phillip Lancaster

Active Member
If you're working in state plane. Then each site could be autonomous. Shooting a point or two from previous setup would be a check after DPOS of each base site.
 

Nate The Surveyor

Well-Known Member
If you have a localize, and the local page is active, then it could appear that it's all in the local system. But, no, it will be using the underlying spc.
This aspect of the Javad system is light years ahead of any other system yet available.
N
 

Glen Yasharian

New Member
So, I have another project where I want to leapfrog the base ahead but maintain the original base station coordinate as Truth by using a common point between the two base setups. I'm leaning toward using the base-shift function which appears to be a simple translation. I recall that after a base-shift and a processing of the new base shots with DEPOS, there is a Localization coordinate in the point screen with the rtk and ppk coordinates.

Does the one point localization routine do the same thing or is it a more rigorous statistical process?
 

Shawn Billings

Shawn Billings
5PLS
As I discussed in this thread previously, do not use one point localization for this task. One point localization creates a local coordinate system. You want to use Shift, found in the collect action screen under the "Point" button.

Begin by starting your base as normal in base rover setup, which I will call Base1. Near the extents of your radio range collect a point, which I will call P1. Move the base to a new location within radio range of P1. Start the base with an autonomous coordinate, which I will call Base2. Return to P1 and set the LS to Shift in collect. Collect the point and apply the shift. All points from Base2 (including Base2) will now be relative to P1 which is relative to Base1.

If you perform DPOS on Base1 and move Base1, Base2 will not follow. You will need to use M-Local to manually move Base2 or use DPOS on Base2.
 

Glen Yasharian

New Member
Shawn:

Thanks for your explanation and your patience. Us dinosaurs get stuck in the steep part of the learning curve, but, I'm trying my best to keep up. The procedure you outline is what I planned to use and seems simpler for my purpose than using one point localization.
 
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