If you really want it to get interesting look up Little Mountain, east of the Pryor's.
Will do. See history is all amongst us all the time.
OleManRiver,
It does my heart good to hear someone call NGA by its original name ... DMA.
Good times.
So true. LOL. I reckon a few of us actually lasted through a few name changes. DMA NIMA and now NGA. Some of my certificates I received over the years and classes all call different of that organization names. Defense mapping school NIMA university then NGA. College lol
Oldmanriver and firestix -- New guys! My first work with them was when it still Army Map Service (AMS) in Bethesda.
Now don’t date yourself my friend. We all still used the same old recording forms I bet. Everything had its place and form either for triangulation or traverse etc. you have us beat though.
Any factor that converts grid distances to ground distances is a combined factor.
This publication explains the difference and calls the resulting adjustment factor a Datum Adjustment Factor (DAF). Other publications I've read call it a Project Adjustment Factor (PAF) or a Surface Adjustment Factor (SAF). The distinction is because it's not a combined factor, it's unique and created to simply raise the plane surface to simulate ground distances with grid.
However, there still will be grid and elevation factors and thus combined scale factors, they are ignored, much like an LDP projection.
The second paragraph says that it's a combined factor. A rose by any other name ,,,,
LOL, yes they do, just don't call it a combined scale factor. 😉
And you didn't.
The grid distance to ground distance is something recent in history. All NGS data sheets publish the combine factor which is for taking ground distance to grid. We often now use or perform the inverse of that. Every point has its own unique one (CF). Often we now use 1 factor for a whole site. In most cases this works as long as one understands the limitations. I often see people confuse the Scale Factor for what a combined factor is for and have even seen someone use the elevation factor x’s the elevations as if they needed to scale those. Our use of some of this in a slang form or as some would say geographical differences sometimes causes more confusion. I have read enough of the publications from agencies and DOT’s that doesn’t help either. But we all mean about the same thing.
LOL! Thanks, Moe! You know that I'm just an old contrarian and mean no harm.
Hey man, I'm glad you're on this site. And just so you know, I've got no dog in this show, but I think it's good to get different perspectives and see different ideas. Deep down we all want a flat earth which would make all this stuff easy, but we'll never get one.
NGS-published combined factors transform a ground distance into a grid distance by multiplication. It follows that a grid distance can be converted to a ground distance by division. Thus, the combined factor converts between ground and grid and grid and ground.
I grew up professionally in a world of Monroe electric calculators and I know that a lot surveyors did, too. Multiplication was efficient, but division was inefficient. When we had a series of operations that required division by a constant, we calculated the reciprocal of that divisor and converted the operation to multiplication.
I suspect that that concept is the root of the DAF. It simply converts division to multiplication. But it was the reciprocal of the combined factor, so it needed a new name.
And that name change introduced a great deal of confusion.
Putting on my contrarion hat, since inverse has a specific meaning in surveying, it should not be used in place of the word reciprocal. Reciprocal is the term taught in math classes, it has a unique meaning, and it's a perfectly good word.
No harm meant; I'm just an old contrarion.
1/X. I see your point for sure. Words do cause confusion at times for sure. I am one of the worst on that. With being dyslexic I use that 1/x button to take and find that reciprocal. I was taught that it was the inverse key. But inverse between two points in surveying does have a different meaning for sure. This is a great site. So many intelligent people from all over and so much knowledge to gain here.
