GPS - Aerial Photos - Mapping

[Hotspotter]

Below is a string of emails exchanged between myself and Jason Syring, a fellow FM member, regarding mapping and overlaying GPS points on aerial photos. Because this worked for Jason, and all of the information/software is free and publicly available, I thought this might help out others trying to do the same thing.

For those of you interested in making maps of deer stand locations on the aerial photos, or marking scrapes/rubs, etc., this is a valuable tool. For the fisherpeople out there, many sunken islands, gravel bars, and mud humps show up well on the aerial photography as well. The information is fairly technical, so as always, feel free to ask any questions you may have!

Quote:

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JASON

Hey Joel –

I was doing some research on the

HSOforum

for GPS coordinates and aerial photos and saw you had lots of informative posts. I saw some of the posts last year about the NAIP photos in the MRSID format that were taken in 2003 and downloaded the Itasca county files as well as the Lizard Tech viewer that was discussed on the LMIC

HSOforum

. Last night, I also downloaded the ArcExplorer viewer because I saw that mentioned in one of your posts.

I have been able to view the photos and they are really great for checking out the area we deer hunt. What I was trying to do (and not sure it is possible) is to overlay some GPS coordinates on the aerial photos. For some reason I thought I saw somewhere that is possible. I load the MRSID file as a layer and then I have saved off a waypoint file as a shapes file (.shp) and load that as a layer as well. I can get the waypoints to show up but they do not appear on the photo – they are at a spot in the viewer that is way below the actual photo. Is it possible to “tie” the GPS points to the spot they belong on the aerial photo or am I trying to do something that is not even possible?

Sorry for the long email but I find this stuff to be really fascinating and love the potential of using for hunting. You were one of the only ones I have seen that seemed to really have a great understanding of this stuff so I thought I would see if you could answer my questions.

Thanks for your time!

Jason Syring

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Quote:

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JOEL

What you are describing is “georeferencing” the waypoints (as shapefiles) to the Aerial Photo (MrSID file). Unfortunately this involves a process called “projecting.” So you’re left with a few options:

1. Re-collect the GPS coordinates in the same coordinate system (or projection) as the Aerial Photo, which is:

Projection UTM, Zone 15, Datum Nad83, Spheroid GRS1980, Units Meters

To accomplish this, you will have to change the units/projection on your GPS unit (as close as possible to what is described above, making sure the units are in meters), and re-collect your stand locations.

Being that they’re in Itasca County, with deer season drawing near, this could be a problem!

2. Project the coordinates you do have from whatever projection they’re currently in (probably WGS84), to the UTM projection. I will probably have to do this for you, as it requires GIS software to do so. I am willing, so long as you can tell me what projection they’re in, meaning you’ll have to know something about your GPS’s current settings. I need to know everything about the current projection to georeference them, or make them “tied” together.

Let me know what you think about this, but you’re close enough to taste it! Don’t give up now! Then we can talk potential of GIS.

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Quote:

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JASON

Ok, let me make sure I understand this correctly. It sounds like it is definitely possible to do what I am trying. The problem I am having is the coordinates from the aerial photos are in a different coordinate system than what I have mine in from my GPS. How would one know what the coordinate system is for an aerial photo – did you find that in their documentation?

So, you gave me 3 options to try to resolve it.

I have really gotten into this stuff in the last year so hopefully I can get this to work. It seems like it could be pretty good stuff even if it is just for our hunting stuff! How did you get into something like this? I had never even heard of it until last year.

Thanks again so much for your help and hopefully I can get this to work!

Jason

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Quote:

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JASON

Hey Joel –

I got it to work and it is pretty cool! I tried a couple of things (#3, #1) without much success. I then decided to try and change my GPS to the UTM and Datum 83 settings and then take the waypoints off. That worked! They all came off in the UTM format and they loaded right in and showed up where I expected them. I have some very specific sights on the aerial photo that the locations are near and they all appeared correctly! It is so cool! Hard to believe that it can actually do that!

Thanks again for your help and encouragement to keep working at it!

Jason

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In the end, Jason figured it out on his own. Basically, he went into his GPS settings, and changed to the appropriate coordinate system. After re-downloading his waypoints, everything aligned.

Kudos to you Jason for figuring it out, and providing the impetus for the post. Jason has proved all you need is a handheld GPS unit, some time, and a bit of know-how to get this done!

Joel

[Deitz Dittrich]

I had the pleasure of working with Joel this past weekend at the Cabelas in Rogers. He was trying to explain this stuff to me, and I can totally see how usefull this could be for people. Kudos to you Mr.Nelson for making this type information available to people!

He's really smart and a nice guy to boot!

[Studer]

Hey Joel,

Is there a HSOforum that you are referencing to or not? Also I have done some experimenting on the terra-server HSOforum and found it very useful. I have been on other aerial photo sites and get a very small picture of the land. However on the terra-server HSOforum, you can zoom way in. Very Cool!! However the latest photo they have is from 1994 I believe. Let me know if there is a different HSOforum to reference for these types of things. Thanks in advance Joel!!!

[woodview]

Basically I just did some searching and answered my own questions.

However I'm wondering how you got into GIS (Joel or others)? Kind of interested in this. Any sites that might give overviews of the more advanced aspects.

Regardless, really awesome to see - I've brought this sort of thing up to numerous friends and while I'm probably far more of a techie than they are I know a number of them have spent hours zooming into where they dropped their first muley's etc.

Need to check out the layers functions you guys are discussing - would kind of like to layer off the forestry site that shows forest age-classes, tree diameters, etc. which I'd recently run across while trying to find new grouse woods.

[Hotspotter]

Woodview:

Now you're getting into the real potential of GIS. Using free, publicly available data to elminate areas that will not be productive......whatever you like to pursue; fish, grouse, pheasants, deer, etc.

This layering you speak of it termed "overlay" or "overlay analyis." Really, all you're doing is taking several datasets, and using criteria to select-out areas of poor productivity.

For example, you're looking to find good grouse cover. Well, I'd start with a few layers:

-roads

-aerial photos (base-map - for confirmation)

-forest cover-type - with stand information in the database

-National Wetlands Inventory - Wetlands data

With these four datasets, and GIS, you could find those specific areas that:

-are 5 miles or more from a major highway (remoteness)

-are young aspen, and/or recently clearcut patches

-are alder swamps

From there, you can elimate those of small size, and/or study the spatial pattern for maximum amount of edge. An incredibly powerful searching tool, used out there much more than people know. Remember though that your analysis is only as good as the data you put in it.

As for how I got into it....guess I started off being a natural resources major, got my undergrad, and realized that GIS was a broad tool I could use in many different aspects of my field. I got some experience with The Nature Conservancy, the WIDNR, UMD, and Yellowstone National Park. Then I went to grad school at the U for it.....where I really honed my skills. An ms is definitely not a requirement for this type of work, it just helped me get some of the extra training and a degree at the same time.

Studer -

The HSOforum we're referencing has data that can be found in two places. The first is an interactive mapper like terraserver. - http://geoserver.state.mn.us/raster2/viewer.htm?Title=Minnesota%20Clearinghouse

The second is the actual data. You can download this with a high-speed connection and view it with special software (per previous posts). This site is: http://www.lmic.state.mn.us/chouse/naip03mrsid.html

Let me know if you have any questions and I can help out.

Joel

[BlueBasser]

Joel I noticed a Northland reference I went there too when did you graduate... I also found that Raster site from the U of M a few weeks ago, it is far superior to Terra Server, thanks for the tips.

[Kodiak]

I use www.maps.googleDOTcom and look up the area and then select satellite view.

[Hotspotter]

Bluebasser:

Hate to date myself, but I was class of 2000.

That school was a trip; I loved alot about it, and disliked much about it too. Really an experience though.

Joel

[Hotspotter]

The google maps are sweet inside the metro, because it's the same data from the LMIC site. It's recent 2003-2004 full color imagery from the Farm Services Agency (some well-used money from the Homeland Security Act ).

Outstate however, I think they're looking at re-sampled quickbird data that comes in at 3+ meter resolution. There's also patchwork datasets used to plug holes in terms of coverage, so it's hard to know what you're getting. Check out the LMIC site, I'm sure you'll be impressed!

Joel

[BlackLabGuy]

I haven't done it yet, (too busy with family, working & hunting) but it appears that you can download GPS waypoints & tracks using Google Earth. The free version doesn't support GPS but the $20 version does. The quality is dependent on where you are at but it seems to be easy to use.

[BlueBasser]

Yeah you graduated on the year I was coming in, so I graduated in 2004. You're right about the school great times and great memories but there were some things that were interesting. Demographics have changed a little bit up there over the last few years. Just to contribute to this post what I usually do with the Raster program is click the little print button then it will bring up a print page then you can copy that picture and paste it into a Paint program. Then i like to draw boundaries and stand sites on there and print them, it is a vary useful tool and much more update then TerraServer