Most likely the projects are "in state plane" but not actually designed and built on grid.
Whatever small level of distortion there is between grid & ground won't make any difference for almost any GIS that the as-built data might get loaded into. While not technically perfect, it's good enough.
High up in the mountains or with a ton of grade change it might start to make a difference...
@olemanriver the state plane projection based on the zone you are working is set prior to collecting the data and the corrections are based on the settings. When the data is downloaded the points are already processed in SPCS.
As for drafting in C3D, I am the wrong person to ask. I am by no means proficient. I know enough about it to draw deeds, import points and do my resolutions and then pass it on to drafting to set the line weights, line types, layering and apply the company drafting standards.
@rover83 gotcha. So for example. I am doing some boundaries now. I started in state plane take and key in the deeds I reduce the deed distances per a few found monuments and get the cf so i am in tbc and a couple ways to do this. But i do understand now most of the time no difference. What gets you or what i see is the zero elevation line that comes In from civil 3d as zero is an elevation in Trimble access or trimble business center. I feel like a idiot. I just can’t get my head wrapped around the drafting flow. My brain is in computational mode. I wasted time today computing a darn third point on a building when it clicked i can just do a couple circles and intersect them. Why my brain is like that i have no idea. I watch someone just drafting they just connect dots and don’t worry if it misses a point its close enough lol. They have it down I reckon. Me i am just so ignorant in this portion. I mean i can get everything connected trim extend but drafting is a art i have not yet conquered.
@chris-bouffard I am glad i am not the only one on the face of the earth that is not a master drafter. I will probably spend the rest of my career using something like traverse pc or c&g Trimble Business center. Civil 3d kicks my rump. I guess at the end of the day if it is correct and meothe standards and doesn’t look like a kindergarten kid drew it i will survive lol.
@rover83 Do you think once the new datum is out Autodesk will make it to where one can design correctly in that system or will it be what it is now. Close enough.
I think that all depends on the state and where you are working/constructing. Generally speaking SPCS2022 will make that distortion much less apparent and often make it disappear entirely (for all practical purposes).
Some states really got with the program and worked up LDPs for statewide coverage.
Others (cough cough Washington cough) decided not to worry about that and ignore the "third layer" of LDPs. Based on the NGS distortion maps and some testing, we could have done better and some projects in the future will definitely see issues if kept on SPCS.
@rover83 where I am they could have used a few LDP for sure. We have one zone then a north and south zone. The problem is in some areas now its not much like .05 per 1000 ft obviously more in some areas etc. I was looking at purchasing a software that computes LDPs but its like 5k a year and for fun I can’t do that as just for my own use. I have been tempted to do them in TBC but have just not had the time to sit down and wrap my head around it. To busy trying to keep crews going and teaching myself the drafting side. My boss has a good eye so if a piece of text is not exactly centered in a building or whatever i have to re do it lol.
I was looking at purchasing a software that computes LDPs but its like 5k a year and for fun I can’t do that as just for my own use
The computations are pretty straightforward, anything that can process raster data can work. We hav ESRI software so I use ArcGIS, but QGIS or even something like Matlab or the free equivalent (can't remember its name) would work. It may not be as slick (mine is defintely not) but it sure beats shelling out 5k...especially 5k every year (!)
I use the USGS elevation DEMs, add the geoid model to get to ellipsoid heights, then go from there. Dr. Dennis' guide for LDP development has worked flawlessly for me so far, and we always confirm our custom systems with either NGS marks and/or field observations.
@rover83 Yes Dr Dennis is a smart cookie. I was actually looking at the software he created but had to step away I guess a he works for ngs now. He and his wife are very good people just easy to get along with and such. Whenever I bring up LDP’s i just get shot down. So i have not pursued it much. I can’t even get them to understand or listen when we have a site that is huge but project A is on one side. They go and scale for that area to ground. Leaving the coordinates looking like state plane. Then proj b a couple years later the do the same thing and wonder why the new area doesn’t match the old area. When i ask where was the scale origin originally they say that doesn’t matter. Yet i have a foot from opus to older published values that all look like state plane. So I keep banging my head against the wall. Maybe i over think stuff but when a client gives me a set of coordinates and calls them spc and all control but one or two is gone and i do opus or vrs and know they agree and miss their point a foot a half a foot 3 feet etc. it is frustrating for sure.
