topic Re: XY Table/Multiple UTM Zones to Single Feature Class in Data Management Questions

XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 19:04:30 GMT

This is a problem I come across regularly and feel there's room to save a step or two.

1.) Field data comes back from GPS or field notes in a table containing UTM Zone, Easting, and Northing fields. There may be multiple UTM Zones (e.g. Zone A and B).

2.) Display XY data, using Zone A as CRS.

3.) Export all data to a single feature class, using the chosen UTM Zone (A).

4.) Set Data Frame CRS to Zone B.

5.) Select and export records in Zone B to new feature class, using Data Frame CRS.

6.) Start editing and delete records in Zone B from the feature class in Zone A.

7.) Merge Zone A and Zone B feature classes into a single feature class with common CRS.

As you can see, this is somewhat convoluted. How do you handle tabular data in multiple CRSes?

Re: XY Table/Multiple UTM Zones to Single Feature Class

DanPatterson_Retired — Mon, 11 Jan 2016 19:54:10 GMT

Our rule? Data in the field are always recorded in decimal degrees, geographic coordinates with a WGS84 datum regardless where in the world they are working (particularly north of 60). The conversion to other projected coordinate systems is done in-house to suit the geographic area and extent. As for UTM, you can devise your own TM projection by changing the central meridian if that makes for better coverage. Otherwise a more friendly east-west projection is used (such as lambert...).

Re: XY Table/Multiple UTM Zones to Single Feature Class

RebeccaStrauch__GISP — Mon, 11 Jan 2016 19:54:13 GMT

Not that this will resolve your issue or make a better workflow, but I don't export in UTM zones from GPS....either decimal degree or another projection that doesn't require a different CRS. But if the data is coming in as you mentioned, that isn't a bad workflow. However, you may be able to write a tool to make the process a bit faster.

edit...looks like Dan beat me to it.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 20:00:14 GMT

We are somewhat stuck using UTM in the field. It's the industry standard (really, the only option ever used), for better or worse. It's easy for field workers to estimate distances using the coordinates, and vice versa. As a GPS can only use a single CRS at a time, they are set to UTM.

Re: XY Table/Multiple UTM Zones to Single Feature Class

ChadKopplin — Mon, 11 Jan 2016 20:02:10 GMT

In the past we have looked at where the majority of points are and where the least error is located. So, if the majority of the points are along a UTM boundary, and the majority are in the left zone, we would set the points to the left UTM zone for this data (lower error on the right side of the UTM zone versus the left). This would be for specific areas, but for state wide data we would generally choose one of the systems previously mentioned.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 20:05:36 GMT

As I replied to Dan, I'm somewhat stuck in a machine bigger than myself with this. UTMs are the only option. I can't expect field workers to remember that just because the data might make its way to me at some point, they need to record a different type of coordinates.

More just looking for a few less clicks between multi-CRS table and single feature class. Unfortunately, as these tables come to me in so many different formats, I don't think I could ever write a script that covers all cases.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DanPatterson_Retired — Mon, 11 Jan 2016 20:06:14 GMT

And if memory serves... or Melita Kennedy could confirm, you have a couple of degrees of longitude...to play with on either side before things go "south" to use an expression. An on our gps units, we can flip between wgs84 and utm with a button press. We find students are quite clever when it comes to remembering that prior to download, I am sure your field workers are as well.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 20:07:45 GMT

This isn't to do with error. As you cross a UTM zone boundary, the GPS chooses which zone it's in and reports/records those coordinates. The resulting table or data sheets then contain those coordinates.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DanPatterson_Retired — Mon, 11 Jan 2016 20:09:33 GMT

That was one of the reasons we use GCS...even though on our gps units (most at least) you can manually chose to stick with one or the other.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 20:11:14 GMT

That would be device-specific. The units/CRS are set fairly deep within the GPS main settings.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DanPatterson_Retired — Mon, 11 Jan 2016 20:14:58 GMT

Then I would look to see if there is an "auto-switch" toggle to prevent border switching. And there must be a quick switch to toggle between geographic and projected coordinates (at least on the garmin (many), leica (?) and trimble (?) units we have)

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 20:20:31 GMT

I suppose DD are useful for GIS users, but not so for the person on the ground. It's pretty handy to be able to get real info from projected coordinates, in metres.

What model GPS unit do you use? By far, the most common unit I encounter are Garmin GPSmap-style units, which do not simply flip back and forth between CRS, without going into the unit's main settings.

Re: XY Table/Multiple UTM Zones to Single Feature Class

MelitaKennedy — Mon, 11 Jan 2016 20:25:37 GMT

Is the data labeled with the different zones? Or do you have to graphically figure it out after adding it to a map?

If the former,

Dump all data into Excel (or other spreadsheet program).
Sort by UTM zone
Copy/paste one of the UTM zones data to another worksheet
Delete that data from the first worksheet.
Now use Add X/Y data on each worksheet.

Possible alternative--use Convert Coordinate Notation to add geographic coordinates to the "table."

If the latter, one possibility is to check what X coordinates are at the zonal boundaries in data's area. You may be able to sort the data using that information.

Melita

Re: XY Table/Multiple UTM Zones to Single Feature Class

DanPatterson_Retired — Mon, 11 Jan 2016 20:29:04 GMT

Out students use a variety of garmin handhelds going quite a way back, that is one of the first exercises that they do within the first few minutes of their first lab...switching between wgs84 DD and UTM NAD83 18N... the variant isn't going to matter a bit if it is NAD83 plainold or NAD83blah blah since the differences are relative and the hand helds only have a certain accuracy which is far worse than the ground based differences ascribed to variants in the nad83 datums. When you are trying to herd multiple classes of 40 through the funnel to generate a dataset, there is only one way to go. They can keep the data in UTM in the field...but...at download time, it is WGS84. We also use DNRGPS because of its multiple output formats and simplicity of use. Are they handling the downloads? If so, might I suggest that before they do it, get them to take a photo with their cell phone of the settings they used in the field and text them back (when in range) to base, just in case there is some weirdness in a certain set of data. This has come in handy a couple of times when NAD27 was more of an issue during the early years of field gps

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 21:02:05 GMT

Thanks, Melita. The tables are often provided in Excel format already, so your workflow would work, although it still has the same problem of duplicating effort (copy/paste twice, import twice), plus having to work outside ArcGIS, plus the potential for me to mess up the entire dataset using Excel sort.

Really, I'm just looking for a less cumbersome way to split a single dataset into two CRS and merge back together, but I'm beginning to see that this may just be a necessarily cumbersome task.

Thanks all for the ideas and discussion.

Re: XY Table/Multiple UTM Zones to Single Feature Class

RebeccaStrauch__GISP — Mon, 11 Jan 2016 21:12:33 GMT

If like Melita ask

Is the data labeled with the different zones?

and assuming these are all starting out in one file, can you

1) import the Excel

2) get a unique list of the zones

3) do a reselect for first zone

4) export to a new temp file,

5) repeat

simplified, but if the conditions are right, I would think this would be fairly doable in a python script.

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 21:13:29 GMT

Just out of curiosity, here is the sequence of buttons I would need to press to change from UTM to DD on a Garmin GPSmap 62s and return back to the map:

Menu-Menu-Setup-Down-Down-Down-Position Format-Position Format-Down-Down-Down-Decimal Degrees-Quit-Quit-Quit-Quit-Quit-Quit

That's 18 button presses. Record the coordinates to the datasheet. Now I need to get back to UTM because I need to know something in metres. That's another 18 presses. At this point, I would throw the unit into the nearest stream.

Re: XY Table/Multiple UTM Zones to Single Feature Class

RebeccaStrauch__GISP — Mon, 11 Jan 2016 21:22:17 GMT

(ugh...lost my last reply)

re: GPS. Is there a way to standardize on the software used to download and provide the data to you, e.g. DNR Garmin Application: Minnesota DNR

I'm not a real GPS expert (although I play one field assignments sometimes), but from what I know is that behind the scenes of all the GPSs the data is collected in (if I remember correctly) WGS84. What the user sees and/or enters is just options for convenience. Since that is the case (to the best of my knowledge) you should be able to output the data in a standard, say lat/long, regardless of the settings on the GPS itself. How easy that is to implement in the field for you.... ???

Re: XY Table/Multiple UTM Zones to Single Feature Class

DarrenWiens2 — Mon, 11 Jan 2016 21:32:00 GMT

Yes, we (I) do use DNRGPS, however, the main issue is that the data coming in is often in the form of paper datasheets (later entered into Excel), with much more information than just the location. UTM Zone, Easting, and Northing are just three fields among many.

The field workers use their GPS for many tasks besides collecting point coordinates, like estimating distances between and to coordinates, navigation, etc., for which they need coordinates in metres, not degrees.

Re: XY Table/Multiple UTM Zones to Single Feature Class

RebeccaStrauch__GISP — Mon, 11 Jan 2016 21:37:52 GMT

understood. Sometimes getting everyone in the field to turn in what "we" need is like herding cats.