GIS Discussion

I agree that this is eventually going to happen and that at some point the legal system will catch up. My greatest concern is the lack of knowledge many surveyors have about geodesy. I have had several conversations where ground elevation is thought of in terms of ellipsoid instead of geoid; and don't even try to explain ITRF and the projections on which the coordinates is based. Coordinates must be in 4 dimensions to include time if they are to used for any legal documentation.

The other problem is the complete lack of official local control within the county/municipality. There has to be something that everyone within the jurisdiction ties to.

Good discussion. I did not read the previous post so forgive me if I am coming into the middle of this.
Teresa

I agree we need to educate many folks, I think that we should include more geodesy in our 4 yr degree programs. We should make these courses practical and hand on. One of the best ways to get there is by requiring georeferencing. This will force surveyors to improve their skills and we would see much improvement.

We need to start somewhere. I am a PE and PS, and I know very little about GIS. I do want to learn, because I see a great potential. I see a need for land surveyors who do not use GIS to integrate this technology into their business practices. A lot or surveyors on this board do use GIS. I want to start by georeferencing all my surveys into one GIS database mainly to track what surveys I have done where and what corners I have found or set.

My nephew is a college grad with a GIS background, and it drives him nuts for me to take perfectly good georeferenced data and knock it down to 5000/5000/100. "WHY?" He asks. "It ain't t flat and the coordinates are too big," I say. I am the one who needs to look at GPS data for what it is and use it accordingly. I have been using GPS for a little over a year, now. I still have a lot to learn, and this board has been a big help. I personally want to see more threads like this that address software, image resources, ideas or methods to set up and extract stored data for a corner or parcel, etc.

When I ask, " what will GIS do?", and I am told " anything you want it to do," I find it a little perplexing. For it to do anything specific, programs, or macros must be written. A database is just a bunch of row and column information that first must be populated with data. Is there a commercially available software that includes not only the GIS software, but contains additional routines specifically for land surveying? To me, this is like buying Microhard Excel. Great software, but no data supplied. I do everything, from populating the rows and columns to writing routines to extract useful and needed data. GIS is a database software that adds aerial imagery and much more. For me to do "Anything you want" is hard to wrap my mind around. Hasn't someone already done this? Is there software out there already set up for the land surveying community?

Harold,
My first reaction is that your nephew does not have a GIS background; he knows how to turn the software on and possibly put a couple of things in one map. He might even be able to make them pretty. What he does not have is an understanding of map projections, the most fundamental knowledge for any geospatial professional.

When doing my research for a class I ran across a thesis on just this issue:
"Integrating Land Survey Data into Measurement-Based GIS". You can find the paper here: http://digitallibrary.usc.edu/cdm/ref/collection/p15799coll3/id/65555

This will probably be over your knowledge right now but it brings home the point about the conflicts between GIS and survey data. But for what you want to do, it is very possible.
What CAD software do you use? You will need to ensure that the projection is properly defined in the CAD. If you have been surveying on local coordinates, I HIGHLY recommend you find a way to tie all of those surveys into one unified system. Is there local control used in your area? Do you use GPS? Also, make certain that the scale factor is correct since this has impact on the projection. If you work in two zones, that is okay, it will work out fine. Just make certain each drawing is in a proper projection. I work in UTM in Afghanistan, but in the states, State Planes works. The big problem with SPCS is corrections for elevation, again proper definition in the CAD.

Just like doing a spreadsheet, setting up a bid proposal, or starting a survey it is the ground work that will decide success. Because all 52 camps that we survey here are on UTM, I literally just dragged and dropped them straight from CAD into my GIS. There is a lot more to do than that if you want a good database, but if you want something quick and dirty to see all of your jobs on one screen and overlay it on a downloaded image such as the local county's aerials or even google, this is all you have to do.... after you have correct projections in your base files.

If you want to talk about it sometime or even bounce some idea off of me as to what you would like to do, feel free to email me.

Oh yeah - keep your nephew away from your files until he learns GIS:-)

teresa

It's going to be up to the GIS "profession" to make the major leaps in progress towards some sort of product consistency before even discussing a national cadastre.

Just here in Ohio there is so much variation in capability, training, and implementation from county GIS to county GIS that it is a running joke among surveyors. You'll need to fix that problem first. Asking surveyors to input quality work into such an environment is currently pointless.

Teresa,

I think you're unfairly knocking Harold's nephew. He realizes that the common practice of some surveyors to use a local coordinate reference system makes the data hard to use in a GIS. This implies to me that he has some fundamental knowledge about map projections or coordinate systems.

Melita

:good:

You don't tell a 2 year old all your knowledge about why not to stick his fingers in the electrical socket, you just tell him not to do it.

Thanks for the link. Very good reading. Jp

Melita,
You are probably right, it's late at night for me and I'm getting grumpy. But putting all of the surveys into one GIS for the purposes of a database of your surveys is not overly complicated. It becomes complicated if you want to use it as your survey data source. It really comes down to what you are looking for from your tool. It sounded to me like harold really wants to have a record of all of the surveys in one place. If he uses local control for everything then getting an aerial image and rectifying each survey to a point on the image will go a long way to giving you a picture of your business records, at least more dynamic than push pins on a map on the wall. If you're utilizing GPS, a lot of problems are solved.

Past my bedtime, I should shutup and go to be.

I don't propose to have all the answers and I agree that we have a long way to go. What my suggestion does, is try to get surveyors to the point where we are outputting data that can be useful to a proper GIS. Mandating filing and georeferencing is the only way to do that.

"Mandating filing and georeferencing is the only way to do that."

And getting it through state legislatures is the only way to do that.