Recently I received an email from a GPS user asking me to review his data. “Something must be wrong with my GPS unit,” he wrote, “the data I collected don’t line up with my other GIS data.” He had attached his data to the email and it consisted of a single file called points.shp.
This is a common scenario. A new user is attempting to do some fairly complex GIS. The workflow of using GPS and then integrating it with an existing GIS is riddled with potential pitfalls that can trip up experienced GIS professionals. Newbies without proper training or oversight can wreak serious havoc on an existing GIS. I am a huge supporter of GIS training. It’s what prompted me to pursue a career at ESRI as an instructor and what keeps me participating in ESRI’s Authorized Training Program as an independent GIS trainer.
Spatial data is complex. There are many different formats — shapefiles, geodatabase, CAD, and many more — each with its own unique behavior. Spatial data has to be properly georeferenced. If it is not – as is all too common with spatial data – you need to know how to asess the problem and which tools will solve it. Some spatial formats can be edited, some cannot. You can convert some formats directly to your desired format while others require a bit more maneuvering. Then there is the information about the accuracy of the data, how and when the data were collected, usage restrictions, and so on. Oh, and let’s not forget about how to share the data with others. Do you send the shapefile’s SHP, the layer file’s LYR, the MXD, or the entire geodatabase? A GIS professional needs to understand all of these issues. These are just a few of the nuts and bolts of GIS.
Add GPS data collection to the workflow and you introduce a whole new toolbox full of more nuts and bolts. Avoiding datum shift, applying differential GPS in the field or back in the office, converting data formats from your GPS format to your GIS, and so on. GPS makes it very easy to go out and collect data for your GIS and it has become extremely popular for organziations to purchase their own GPS equipment and collect their own field data. It is seemingly much cheaper to do it in-house than to hire a contractor. Whether or not that is the case depends entirely on the training and skill of both the GIS manager and the GPS field workers. I see too many emails like the one above for me to believe that organizations who do not invest in proper GIS & GPS training are really saving money. They are running the risk of generating a whole lot of error-ridden data.
I’ve been helping organizations integrate GPS and GIS for years and I’ve identified the common pitfalls the GIS professional faces. I am adamant in my training about educating GIS users how to avoid these pitfalls. My Working with Coordinate Systems in GIS and GPS training CD addresses the number one pitfall. You can view a sample of the course here and order it by emailing training@geomattix.com.
Tags: Coordinate Systems, GIS Training, GPS Training, Integrating GIS and GPS
Great Post. One issue I see almost every day is the misuse and abuse of the three letters GPS. I hear people say, “I GPS’d the points and ……” The point is that GPS is a term with many many meanings to me. I own many GPS receivers, from a couple hundred dollars to my first two Survey Grade which the package deal was $122,000 back in 1992. My point is that saying “GPS” is like saying “Lunch”. Not sure what you had today for “lunch,” but we all probably had some form of “lunch” even if it was water and a package of cheese crackers. I applaud your training and desire to educate, not just newbies, but all of us. GPS is an awesome tool for all of us to use, and as Dr. Jan Van Sickle points out in a recent audio interview, we need to know how we get the answers. As a land surveyor, I want to add one more quote from a surveyor older than me. “You know the good thing about GPS? – You get a coordinate… You know the bad thing about GPS… You get a coordinate.”
January 29th, 2010 permalinkHave a great weekend and keep the knowledge on-going. My focus is on training land surveyors as that is how I make a living using GPS and GIS in the private sector. Please add to my efforts at http://www.thegeoexperts.com. That is where the Dr. Jan Van Sickle audio interview is under the “interview” tab.
Robert -
January 29th, 2010 permalinkSo true about using the ‘word’ GPS as a verb! I get a kick out of books and movies that have characters using GPS underground.
I’m glad to see you, as a surveyor, taking a shining to GIS. I’m sure you agree that one of the biggest pitfalls in GPS data collection and GIS integration is datum shift. I see it with the mapping grade GPS all the time.
Your website has a lot of good info — I look forward to more.
Thanks Michele. You’re right on. I have a document that might be an additional useful resource to your CD entitled GPS To GIS–A More Perfect Union, on http://edcommunity.esri.com/arclessons. It strictly focuses on low-end tools that the educators I work with use, but even in that realm, there are oddities that occur with different systems, labs, operating systems, and so on.
January 30th, 2010 permalinkIn the above post, many “low end” GPS users are not aware that they have the ability to change to datum and projection in most handheld data collectors. It is not a version of software, as much as settings on the GPS device, no matter how small, that the user can control.
February 2nd, 2010 permalinkWhat this means is that a position can be almost 200 or more feet off, if you think you are in UTM METERS and someone has set your default to be NAD27 US Survey Feet. Knowing about datums and projections is a good thing, and even better, is that most all GIS software is very capable of handling data from different coordinate systems.
Point to make here is that GPS “out of the box” makes it appear you need little training to push the buttons and that is true.
You do need training to understand the answers and whether they are good or not for the project you are working on. I LOVE GPS, just scares the heck out of me, when I see property lines being “GPS’d” by folks walking around a neighborhood, and taking GPS positions on fence corners to determine the location of a property line. I am NEW to the Surveying profession in relation to my age. Therefore, I had the same “I don’t understand” expression when people would let me know the extreme value of having precise, accurate, and repeatable coordinates, and to get them, it has taken me years of study and surveying. I still attend conferences and learn all I can, and that is my challenge to anyone involved with this awesome tool for GIS, we call GPS.
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June 12th, 2011 permalink