Indeed, it's powerful stuff. From ChatGPT, I learned that, at the lowest level, Trimble always collects ground data and converts it to grid, state plane if specified and no scale factor is entered. Entering 1 as the combined factor prevents that conversion from taking place, so everything is stored as ground.
But, as you pointed out, there are endless combinations of inputs that can produce all kinds of output. The trick seems to be not to create a garbage in, garbage out scenario.
The saving grace in a lot of cases seems to be the power of TBC to undo things done in Access. Undoubtedly, other systems providers have similar final control aspects.
Fascinating. I'm honored to be tolerated here.
Entering 1 as the combined factor prevents that conversion from taking place, so everything is stored as ground.
You might want to revisit that.
@mathteacher oh if you only saw some of the garbage in I deal with sometimes lol. Yeah the biggest thing I believe for any one using any software is to first understand the science behind it the math. Then figure out what the software developer was trying to achieve and make sure you check it and follow the manufacturer flow and settings. Anytime I update or upgrade any software version I always check that against known things. I use NCAT a lot every time Trimble updates the coordinate system manager. And I will look at the scale the elevation and cf. to compare. I have seen it off and once was way off in Trimble they had a patch very quickly on that one.
@mightymoe are visit what. Did I miss type something
The Emperor and Vader are closing in on us. On the other hand, 2022 is now 2025 and NAD83 is still chugging along.
@mightymoe are visit what. Did I miss type something
If the scale factor is set to 1 with a projection assigned then the values are on the projection, not ground. Maybe mathteacher meant no projection/no datum, but it reads differently. I can't speak to what goes on with no projection/no datum, that's not a program I've ever used.
The Emperor and Vader are closing in on us. On the other hand, 2022 is now 2025 and NAD83 is still chugging along.
The office pool has a mean about 2031.
@mightymoe oh gotcha. Yeah that chat gpt thing didn’t make a lot of sense on that to me either. I use no projection no datum when I must do site calibration. I have used it years ago but did the whole set a nail called it 10000 5000 elev 100. And laid out a line on geodetic north. No grid projection so geodetic north. Tested it against a sun shot and was close enough to meet some paper pushers idea of he wanted a true north line marked from a spot so he would know where north was. I said well I could have given you the convergence angle from state plane. He wanted it done his way. We said ok. So I did and did the Astro. As well. He checked us with his phone compass. lol.
No, I meant what I typed. It's just so fascinating.
In just plain old Google, type this into the search field: what happens in trimble access when a projection is defined and a combined factor of 1 is entered?
No, I meant what I typed. It's just so fascinating.
In just plain old Google, type this into the search field: what happens in trimble access when a projection is defined and a combined factor of 1 is entered?
Are you saying create a projection? Or are you trying to say use an existing projection?
Two different things, there isn't a reason to put 1 on an existing coordinate system (I don't think you can anyway), if you create your own and use a Scale Factor of 1 it puts you on the ellipsoid. You can use a default TM projection under Project Settings and Coordinate System. Or for a more advanced roll your own you can try to set it up under Coordinate System Manager. Still a 1 in the local site setting will place you on grid. A 1 in the projection will put you on the ellipsoid. 1 as a scale won't put you on ground unless the ellipsoid and ground are the same.
I don't know of a place in Trimble to put a Combined Scale Factor except the Local Site Setting, which will put you on grid if you use 1. If I use 1 for a scale factor creating a projection through my office, grid will be 4000' below me.
. Entering 1 as the combined factor prevents that conversion from taking place, so everything is stored as ground.
Mathteacher, I googled what you said to google. I interpret it a little bit differently. I believe this phrase "This means that the software won't apply any scaling or transformation between the projected grid and the actual ground. In essence, the projected coordinates are directly used as ground coordinates" is saying the coordinates being produced for the point measured will be on the projection and they will not be scaled to ground. This is because you told the software that projection and ground are equal at this location when you specified a combined factor of 1.
I may be wrong but I believe a geodetic position is gained then converted to a projection position (state plane if that is the projection selected) then converted to ground by the combined factor. Entering a combined factor of 1 makes your ground coordinates equivalent to your projection coordinates. So I believe slightly differently, that everything is stored as projection coordinates. You can view either but if your combined factor is 1 they will be the same when viewing projection coordinates and when viewing ground coordinates.
Entering a combined factor of 1 makes your ground coordinates equivalent to your projection coordinates.
Mostly, but not 100% correct. Consider a projection with a scale factor other than 1
Entering a combined factor of 1 makes your ground coordinates equivalent to your projection coordinates.
Mostly, but not 100% correct. Consider a projection with a scale factor other than 1
If you're on a projection, then enter 1 in the Local Site as the combined scale, it multiplies the projection distances/coordinates by 1, basically doing nothing, if you know of another place in Trimble (with a projection defined) to enter a combined scale I'm interested to hear of it.
Yes, and that's the way a lot of people interpret it, But I think that Trimble always measures (or calculates from GPS) ground distances and then applies a projection if one is specified to get grid coordinates. Now, there's confusion here between "local grid" and "grid." Trimble seems to define "local grid" to be its ground coordinates and then applies combined factor to get its "grid" coordinates.
But the scale factor set to 1 overrides that calculation. The software interprets the 1 to mean that grid coordinates, which it wants to calculate, are the same as local grid coordinates, which it knows.
Don't LandButcher and OleManRiver think that 1 means ground?
If I called Trimble, I would be labelled spam, but a Trimble licensee could call the guy Mark something in Georgia who did the video I linked to somewhere above and settle the question once and for all.
It would be great to have Trimble verify one or the other.
@jimcox OK maybe I should have said "Entering a combined factor of 1 makes your projection coordinates show the same value when you ask to view ground coordinates. Either way, I believe you should be getting coordinates on the projection when you take a measurement. If you want some other coordinates (ground for example) you need to allow a combined scale factor to be used.
See, that assumes that Trimble collects grid coordinates, but I think that it collects ground coordinates. Hence, the CSF of 1 is applied to ground coordinates.
That's why 1 = ground.
Grid N=1875064.56 Grid E=1428694.78
Ground N=1875505.20 Ground E=1429030.53 Combined Scale Factor of 1.000235
Grid N=1875064.56 Grid E=1428694.78
"Ground" N 1875064.56 "Ground" E=1428694.78 Combined Scale Factor of 1.000000
Trimble Business Center 2024.1
Straight out of Trimble today
@mathteacher I definitely don't know, but isn't Trimble's RTK determining lat long and ellipsoid height? For each lat long there is an equivalent state plane grid position. Why would lat long be collected then a ground position calculated only then to convert to state plane by a combined factor? That seems to be an incorrect method of determining state plane position. But maybe that is what is happening.
That's what happens without a combined factor entered. Entering the 1 overrides that state plane calculation and leaves the ground coordinates intact. It tells the system that the local coordinates (ground) are the same as state plane, though they're really not.
Thinking they're the same, Access makes no change to them.
OK, did you convert those grid coordinates back to ground before you entered the 1 combined factor? If you didn't, and I think that you didn't, then the 1 preserved what you had with no changes.
Go back and start with ground coordinates and a 1 combined factor and see what you get.