If everyone would understand and use unmodified geographic coordinate systems from field to office all these problems would cease. I can tell you this through experience. If SPC is unacceptable because its too distorted create a geographic system that is not and use it. The thing is everyone has to have the parameters defined in the software they are using. This should be a basic requirement to understand to the field technicians and the CADD technicians. The first thing you do when using the field or office software is check to see if the Geographic definition is set correctly. After that you can reference in any other file that is geographically defined in any other geographic system and it will overlay just fine. (If you software is worth a hoot)
Time to get up to speed people!
leegreen, post: 442980, member: 2332 wrote: Moe,
I agree. Too often the surveyor feels he needs to create a new coordinate system, thinking it makes the project easier. In reality it makes things harder on the client and everyone else using the data.
I've seen surveyors hold a single monument with SPC coordinates, then use ground distances and Geodetic azimuths, based on the single point. What a mess this makes for anyone else trying to use this type of data.
I did that early on (1996 I think), easy for me, but it was a mess for all the people using it.
I wanted a system that would plot on a quad sheet fairly well, and would be ground and would be close to true north. Then the project expanded, got yuge, it became a mess, basically it was an LDP with defined parameters, but no one else could use it.
So I would have to convert it all the time, from state plane (27 and 83) to UTM, usually in meters.
You learn the hard way.
[USER=2332]@leegreen[/USER] This is what I ended up doing, the distortions were not as bad as I thought. This is also what we did for the DEC Food Protection projects, but they were much shorter. We're documenting it using those same notes. I tend to agree on keeping everything in SPC for easy integration with other data. I usually do small surveys in the bastardized "local" SPC with ground distances just so I can reference them into my GIS and reference in some basic GIS data. We don't usually put coordinates on those maps and only the meridian is referenced to SPC using RTK observations. All of this is noted on maps. If there is one thing all you guys have drilled into my head over the years...it's to document things on the face of the map.
tomchurch, post: 442848, member: 10174 wrote: I need to do a 20 mile ROW survey in an E-W direction in the NYSP East Zone. Original survey was done using ground distances...Centerline and offset method. My requirements are to do this in grid for engineering design. Part of me wants to do it using multiple scale factors to keep the distortion low...But how do I rectify the boundary with this? Can I? Should I? The realistic option seems to be that I use one average scale factor for the job, but this of course means large distortions at the edges. I know of a survey group that manages over 150 miles E-W using UTM and dealing with the distortions..."It's only math after all"
I'm sure some of you have an opinion or two about this:p. Also I love the surveying emojis :gammon::plumbbob::stakeout::totalstation:
You could use Lambert grid and have one scale factor since it's E-W
A geographic user defined system for boundary work should overlay into a SPC defined map perfectly. Just sayin...
You could lead a horse to water but you can't make it drink.
[USER=449]@linebender[/USER] I'm interested in this and plan to research it a lot more.
linebender, post: 442994, member: 449 wrote: A geographic user defined system for boundary work should overlay into a SPC defined map perfectly. Just sayin...
You could lead a horse to water but you can't make it drink.
I agree, and most of the users you will deal with are very educated, but try making your user defined system plug into a hand held that a stream expert uses, or permitting companies, or downhole engineers in Texas while you are on the phone with them, or emailing back and forth,,,,,,
Just saying, if you take on an LDP for a highway project be prepared for the phone calls, emails, meetings, ect.
MightyMoe, post: 442999, member: 700 wrote: I agree, and most of the users you will deal with are very educated, but try making your user defined system plug into a hand held that a stream expert uses, or permitting companies, or downhole engineers in Texas while you are on the phone with them, or emailing back and forth,,,,,,
Just saying, if you take on an LDP for a highway project be prepared for the phone calls, emails, meetings, ect.
That's pretty funny considering what I do. I've worked in route surveying for 40 + years. It took about a year for the phone calls to die down. It was worth it.
linebender, post: 443025, member: 449 wrote: That's pretty funny considering what I do. I've worked in route surveying for 40 + years. It took about a year for the phone calls to die down. It was worth it.
Same experience here.
First, if there's an appropriate (for your error budget) existing documented CS - use it!
If not - go with a new LDP and try to anticpate other uses in the area - design it to work on multiple projects.
linebender, post: 443025, member: 449 wrote: It took about a year for the phone calls to die down. It was worth it.
My experience is that for a project team to adopt the LDP (you will be working with a wide range of users) you need to document it clearly and provide a .prj file for the CS.
I include instructions, include info on limitations, intended use, and screen shots of it being defined in a number of software (ACAD, LGO, ArcGIS) and make that available on our website. Include a CAD drawing with the CS already attached and anyone that opens the drawing has the opportunity to import the CS. Here's a link to http://www.survbase.com/downloads/survbase-pmrail-grs80-coord.pdf&apos ;">sample documentation that we've used for the last nine years.
Talk to your local DOT/DNR or other advanced survey agency about it before you design and implement it - they may have other uses for it and may be willing to adopt it - OR it may accelerate their development of an LDP CS that is appropriate for your project.
Yes... there will be folks who never get it - nothing new about that - there are folks that never get SPC either.
The wetland scientists can still survey in lat/long on their handhelds - if they are staking out they'll have to get lat/longs in ArcGIS or AutoCAD or [REDACTED] or ??
If you've got the .prj file and you've got the CS defined in a template CAD drawing - any other properly referenced geodetic data inserts in the proper place each and every time in C3D, ArcGIS, [REDACTED], BMG, etc.
If you do it right, you'll see other projects in the vicinity adopting it.
linebender, post: 442994, member: 449 wrote: A geographic user defined system for boundary work should overlay into a SPC defined map perfectly. Just sayin...
You could lead a horse to water but you can't make it drink.
linebender,
Would you mind describing to me what a geographic user defined system is? All I can think of is that you're modifying the ellipsoid parameters like was done with the county coordinate systems in Minnesota (and Wisconsin's WCCS before they switched to WisCRS).
Thank you,
Melita
linebender, post: 443025, member: 449 wrote: That's pretty funny considering what I do. I've worked in route surveying for 40 + years. It took about a year for the phone calls to die down. It was worth it.
If the DOT is on board like Oregon, I would be all for it,,,,,,,but for a one off,,,,no thanks,,,,I do it how the DOT book prescribes for the DOT,,,,, no way I'm doing it again for other clients, it would be endless
mkennedy, post: 443107, member: 7183 wrote: linebender,
Would you mind describing to me what a geographic user defined system is? All I can think of is that you're modifying the ellipsoid parameters like was done with the county coordinate systems in Minnesota (and Wisconsin's WCCS before they switched to WisCRS).
Thank you,
Melita
Google IaRCS Handbook and read chapter 2.2.3
linebender, post: 443122, member: 449 wrote: Google IaRCS Handbook and read chapter 2.2.3
[SARCASM]to be fair, linebender is super extra careful when they get near that one contour line in Iowa[/SARCASM] ;):rolleyes::D
Rankin_File, post: 443124, member: 101 wrote: [SARCASM]to be fair, linebender is super extra careful when they get near that one contour line in Iowa[/SARCASM] ;):rolleyes::D
I hear ya. We do have a few counties with 600 - 800 ft of contours. I know that's about 1 contour for some of you. When you get out of that range I'll defer to Loyal for LDP design.
tomchurch, post: 442935, member: 10174 wrote: If I were to use a custom projection can I still load in GIS data? I need to overlay a ton of stuff previously collected including 1 meter DEM from NYS, orthos, FEMA data, and other data collected and processed by others (mapping grade GPS based). We're also going to be conducting a UAS survey of parts of the project.
Sent from my SM-G935V using Tapatalk
I use them all the time and share data back and forth. We have inhouse Engineers and Scientists that know geodesy better than most Surveyors..
MightyMoe, post: 442956, member: 700 wrote: What generally happens is that a user; geologist, wetlands specialist, bridge engineer, biologist,,,,wants the data to merge into their database (often these tasks are farmed out). If it's state plane related then that works easily, if it's an LDP then it's a PITA for them. When an engineer designing a bridge needs to calculate the drainage basin and it's millions of feet from any database, you will be getting a call and then probably translating the data over to state plane for them.
Today so many programs are set up to automatically download or upload files and drawings to google, bing, geological databases, ect. that I've found it so much easier to go with the flow, make it easy for them. Most LDP's don't talk all that well with AutoCAD, bing, google, not that it can't be done, but it isn't all that simple. And if you do a Lambert,,,,,,,,good luck with that.
Sounds like it isn't for DOT which explains the reason why there isn't a set procedure. Even more reason to make it easy on yourself, if the scales are small State Plane for the whole project may be the best. I've never seen a DOT road project on state plane(too much elevation here), they have always been on surface coordinates with state plane coordinates multiplied by a Datum Adjustment Factor.
The last thing needed is to introduce .3'-.7' of a foot per 1000' into a road staking project.
One difference for us is the data is folded, spindled and mutilated in house. The mix and match issues simply dont come up. Part of the reason is that I design projections to convert easily and share metadata properly.
LDP is not always the solution. Done correctly they have less distortion than a blanket scale factor and they eliminate the need to publish multiple factors. If it doesnt accomplish that SPC is a logical choice.
mkennedy, post: 443107, member: 7183 wrote: linebender,
Would you mind describing to me what a geographic user defined system is? All I can think of is that you're modifying the ellipsoid parameters like was done with the county coordinate systems in Minnesota (and Wisconsin's WCCS before they switched to WisCRS).
Thank you,
Melita
Melita,
I think Linebender is referring to low distortion projections. They basically involve utilizing a standard projection (Transverse Mercator or such) centered and sized over the target area to reduce the grid scale factor and then manipulating the ellipsoid to minimize the sea level correction factor. While you can achieve the later by modifying the ellipsoid a better practice is to determine a projection scale factor at the origin of the projection that best fits the local terrain. This projection scale factor is a common component of any projection. That is how we did it in Oregon and if I'm not mistaken, that is how the WicCRS is computed.
If you choose to reduce the grid to ground please remember. Truncate the damn things, if it looks like a SPC them the stream guy think it is one because he will never look at or see the meta data.
John Putnam, post: 443219, member: 1188 wrote: Melita,
I think Linebender is referring to low distortion projections.
Yep, I guess I take too much for granted. And we were not too proud to copy what Oregon did.