DPOS - Private Coordinate System

Mark Wheeler

Active Member
When using a Low Distortion Projection (created from State Plain), is it possible to easily DPOS a point on the LDP? There is a check box on the DPOS site for "Private coordinate system", but it is not clear whether I can obtain the coordinate results on an LDP.
Mark
 

Nate The Surveyor

Well-Known Member
Mark,
I think I can supply information, for your benefit.
1.) The CORE coord system in the LS is LAT LON. From there we take a trip. Alterations, based on epoch date. This CORRECTS the fact that pieces of the earth are MOVING. Such as Plates of the earth are MOVING.
2.) From the Lat Lon we get a projection. That's a BIG flat spot on the surface of the earth. This would be like SPC Arkansas South, Arkansas North etc.
3.) From there, we get a LDP. Low Distortion Projection. That's a LITTLE flat spot, co-related to the SPC that underlies it.
So, what we have here, is a Lat Lon, then Math applied, to it, that shifts it by the epoch date. Then we via math, PROJECT that to the surface of the earth. Then, via math, we make a LOCAL system, or LDP. All this is MATH. The core is Lat Lon.

So, you have a selection of PAGES. Simply set PAGE zero, to LAT LON. Page 1 to SPC. Page 3 to LDP. Now, as long as you select the page correctly, you will be able to PRETEND that nothing is going on, while all that math is going on, for you.

It's a dream come true, isn't it?

Ask more questions, learn more.

Nate
 

Mark Wheeler

Active Member
Nate,

I understand collecting a point on the LS on an LDP. I want to then process a JPS file through DPOS and have it relate to the LDP versus the State Plain Coordinate System. Not sure how or if the DPOS site can produce these results. I can then compare the RTK point (on LDP) to the DPOS point collected along with the RTK point.

Mark
 

TonyC

Member
DPOS will only output Lat/Long. If you use DPOS from the LS then, as Nate said, the LS will do the transformation for you and display the coordinate in your LDP on the Page you have set up for the LDP. If you are using a 3rd party software, then you will need to recreate the transformation to convert from Lat/Long to your LDP using a Helmert transformation or similar.
 

Nate The Surveyor

Well-Known Member
IF you make/create a LDP in the LS, and then insert the OTHER SOURCE LAT LON into the LS, as straight lat lon you can likely output them, using the LS to transform them into your LDP.
I do not know how to address the Epoch Date.
N
 

Mark Wheeler

Active Member
Nate, I was hoping that the "private coordinate system" check box on the DPOS site would give a means to add the LDP from the LS and do the transformation in the DPOS report (N,E,Z). But that is apparantly not what the button is for.
Mark
 
Top