Ag Geek Speak

10.5 Tiny Bytes: What's the Deal with UTM?

• A Podcast for Precision Agriculture Geeks • Season 2 • Episode 11

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Using the correct UTM (Universal Transverse Mercator) zone is crucial when working with GIS data mapped to a UTM zone. We explain how projections work to translate locations from Earth's spherical surface to flat maps, and why UTM zones are critical for accurate agricultural mapping.

• UTM divides Earth into 60 zones, each six degrees of longitude wide
• UTM choice errors cause maps to appear in completely wrong locations, like oceans
• Creating maps in the wrong UTM zone leads to unusable prescriptions for field operations
• Maps created in one UTM zone but opened in another will show incorrect positions
• Farms located on UTM zone boundaries may encounter projection issues more frequently
• Always verify your UTM zone settings when working in mapping software
• Turn on background maps to confirm your fields are projecting in the correct location
• Reprojection tools in ADMS can help fix UTM errors

Avoid the sharks and floaties, check your UTM!

https://gktechinc.com/




Jodi:

And now it's time for a Tiny Byte of knowledge. Hey, Sarah, I opened up one of my zone maps the other day and I turned on my background maps and opened up in the ocean. Why?

Sarah:

What happened? You don't farm in the middle of the

Sarah:

Atlantic ocean. What are you talking about?

Jodi:

no, we're a little bit drier than that in western North Dakota, unfortunately, or fortunately I bet you are well, Jodi.

Sarah:

The recommendation I'm going to have for you is check your UTM zone. Chances are that raster map was made using the incorrect UTM, which is why it is projecting in the incorrect place.

Jodi:

Oh my gosh, what is a UTM and what is a projection?

Sarah:

Well, let's start by talking about what a projection is. A projection is the idea of taking location data from. You know the earth, which is round. It's a sphere. So you know that whole idea of taking a round ball and the location that you might be on and putting it onto a flat map. Okay, think about taking an orange and peeling peeling an orange and then making it flat on a piece of paper. It's not going to be completely perfect and we need to figure out how to project our locations and our maps from this round earth onto something flat. So that's the whole idea of what projection is. There's a lot of different ways of doing projection. Many different models exist, but one way that we can project correctly is by using this concept of UTM, utm.

Jodi:

That sounds dangerous. What is a UTM?

Sarah:

Well Jodi, UTM stands for Universal Transverse Mercator. Isn't Mercator a fun word? I love that word.

Jodi:

Sounds very Spanish. Explorer 1600s, 1500s, 1400s.

Sarah:

Isn't that interesting that that's also when we discovered that the world was round.

Jodi:

I don't know, Sarah.

Sarah:

I still have my doubts, but anyways you know, creating maps would be a lot easier if the world was flat, wouldn't it? But it is not, and thus continues the conversation about UTM, universal Transverse Mercator. This is a mathematical model where positions, satellite-derived positions, can be corresponded with positions on a standard map. Okay, and so one of the things that we can help to kind of frame up our mind about this is how, like, the sizes of things on the earth when we project it onto something flat versus when it's in that globe, can look different. You know, think about something about, like, what the size of the United States of America looks like on a globe and then think about what the size of Greenland looks like on a globe, and then think about what that looks like on a flat map. Greenland looks way bigger, doesn't it? It's because we're trying to put it onto something flat.

Sarah:

So we use UTM, universal Transverse Mercator projection models to help us translate that concept of round onto flat, and we certainly use that in our mapping software, adms mapping software, adms here at GK Technology. So UTM it divides the earth into 60 zones. Do you know how wide these zones are? Are they six degrees wide? They are six degrees of longitude. Wide is how wide they are Now. There are a couple of exceptions to the rule, but for the most part they're all six, six degrees, six longitudinal degrees wide.

Jodi:

So what it sounds like is like what we run into when we're just using a regular like map projection, like what you might be familiar with in school, right, where Greenland looks really big and Antarctica looks really big at the north and south end of the map. What we're trying to do with the UTM, it sounds like, is like reduce the amount of distortion at the north and the south ends of of the map that we're trying to make right, because, like when we think about it, we're trying to take a round earth and trying to take that round earth and project it onto a flat computer screen and then also, you know, work with it on our flat monitors that we're trying to use to vary our components. Okay, so that's what those six degrees helps us do is these long strips reduce the amount of distortion that we're seeing and allows us to actually make accurate measurements across, you know, a UTM zone and make it flat without distortion or minimize Absolutely.

Sarah:

And project it correctly, right? So I don't know if there's any of our software users out there listening to this podcast, but if you are and you have mapped incorrectly in a UTM zone, you will notice that the map that was made in the incorrect UTM shows up someplace completely bogus on the globe once it's projected back into the normal. If you don't correct the UTM zone projection and you just open it up in the wrong UTM, it will project it in a very bogus location, someplace that doesn't make any sense at all.

Jodi:

Like me finding my field in an ocean.

Sarah:

Exactly, and there are more customer calls that we deal with on this particular issue than what a guy realizes. And so if you actually create maps in the wrong UTM and then you go back to the correct UTM, those maps will be incorrect, all right. If you open a map that was created in the correct UTM, but you open it in the wrong UTM, it will also not be correct. At the very minimum, you're going to see the angle change on your screen, and so it's just really important that you create and open in the correct UTM. So software users always check your UTM zone. If you turn on a map and it is not projecting in the correct place, you need to reproject it.

Jodi:

There are tools within ADMS software to help you reproject into the correct UTM zone, and so if you need help figuring that out, let us know, and if you work in those areas, that where you're on two UTM zone breaks which is very common that's a very common thing to have happen. You may deal with this problem a little bit more than others, but just be careful. You know, when you're working in a field, make sure that you're working in the right UTM zone. Double check it, triple check it. Turn on your background maps. Make sure that you're working in the right UTM zone. That'll ensure that there's not any problems when you're trying to combine and create layers and create maps.

Sarah:

And then also we'll make sure that there's no errors when you're writing out prescriptions to controllers as well. And again, if you create a prescription in the wrong UTM and it goes out to your tractor for a variable rate prescription, it will not be correct. And yeah, chances are that controller won't even be able to find the GPS locations for that field in there. So that happens. That's what's going on, so take home message.

Jodi:

So, sarah, what you're telling me is that I don't need to buy floaties and like a boat to farm my fields. I just have to make sure that I'm in the right UTM zone when I'm working in ADMS and dealing with my GIS data.

Sarah:

That's right, Jodi. Skip the sharks, skip the floaties.

Jodi:

check your UTM zone, Tune in next time for a tiny bite of knowledge from GK Technology, where we have a map and an app for that.