Shawn Billings, post: 432472, member: 6521 wrote: In either case, it's a good idea to make sure that the underlying coordinates are good geodetically (CORS based rather than autonomous, or Here, based), and to have a report that can be reviewed later.
I always, without fail, make sure we have good underlying geodetic coordinates. I could see where there could be instances where someone had to do a site calibration in the field that was based on a Here position, but I never have a base running on a Here position that isn't collecting static observations as well.
It's pretty painless to import a site calibration into TBC and to report the parameters, you just don't see it too often. I'll see if I can create an example.
Well well well. This has morphed into a discussion about localizations.
First, we are surveyors. That means we investigate stuff. So, in the name of "Knowing" and "investigating", I comment.
And, when performing a retracement, that was done WITH a localize, with in inclined plane, ie, "Warped", we have to understand HOW and WHY these things happen. The mechanics are valuable to be proficient with . 3 pt localize, holding 3d on all 3 points, can give "Bad Medicine". And the residuals may not show a bad elev. Especially on a corridor. Such as a highway, (Long NS, and short EW)
Second, when working in SPC, there are a number of ways to do things.
A.) You can do your whole job in SPC, scaling the deeds to SPC. Then, when publishing, add the CSF, and publish a few coords, on your work, so that others can tag into your SPC, and scale to ground, as needed.
B.) You can keep your data collector pure SPC, and download the job, and scale it to ground. Then, when transferring the job, you scale the coords, back to SPC. In this method, you can choose your scale BASE to N 0000 and E 0000. Or, you can pick a point on, or near the middle of your job, and NOW, the aerial photography, which is on SPC, remains related, albeit, with a minor error, in scale, but that is kept local.
C.) You can do it with a data collector, that ALLOWS you to KEEP your SPC intact, and allows you to import and export LOCAL coords, WHILE maintaining the integrity of the SPC projection. This option C, is what I often do.
I know another surveyor, who does it ALL in spc, and on small jobs, never even addresses the fact that it was SPC... (as in scale). However, there is around 0.02' per 200' error... He treats this as immaterial...
I have even thought of a little utility, that you set perimeters, in. So that, SPC goes in one end, and Some LOCAL stuff goes out at the other... and simply run the coords through this utility, when going IN and OUT of the data collector. The utility resides in the desktop computer.
But, so long as we maintain the integrity of what we do, it is immaterial, HOW we solve this.
Now, to quote Shawn Billings: "The earth does not submit to a mathematical model very easily".
We all have to learn about it.
That is what I am trying to promote. I am trying to promote better surveying.
Any way I can.
Nate
Nate The Surveyor, post: 432591, member: 291 wrote: I have even thought of a little utility, that you set perimeters, in. So that, SPC goes in one end, and Some LOCAL stuff goes out at the other... and simply run the coords through this utility, when going IN and OUT of the data collector. The utility resides in the desktop computer.
I have such a utility. It's called Star*Net. I use it this way on many projects.
Jim, that's interesting. Thanks.
N
