GPS for surveying

[The Black Pearl Crew]

I am interested in producing a preliminary survey of a piece of property I wish to develop. My main goal would be to mark out lots using waypoints and then sketch out a survey map for reference use. I definitely want to draw out the lot lines and calculate the area of the lots. This is mainly to get a preliminary layout of the land before calling in an actual surveyor. I'm new to geocaching and I've used my old Garmin eTrex legend for my first 100 finds. I am definitely looking to upgrade and want to make sure I get a unit and the software I need to also assist me with the surveying aspect. I have never used any software in conjunction with my handheld and I'm not even sure what options are available. Any advise would be greatly appreciated. Thanks in advance.

[+Redwoods Mtn Biker]

Do you realize that a consumer-grade unit is unlikely to give you better than 10-20' accuracy?

[+jeffbouldin]

Delorme has a mapping product just for what you want called XMap7 that works with their PN-34/40 GPSrs. I have the PN-30 and it is an excellent unit. Full paperless and very accurate.

[+dakboy]

Delorme has a mapping product just for what you want called XMap7 that works with their PN-34/40 GPSrs. I have the PN-30 and it is an excellent unit. Full paperless and very accurate.

No more (or less) accurate than a Garmin Oregon, as they both use the same GPS chipset. Any accuracy "advantage" would be due to a newer/better version of the GPS firmware provided by STM.

 

Any consumer-grade unit is not suitable for true survey work. You can get a ballpark idea of the space you're considering, but don't use it for any final decisions.

[+Timpat]

I am interested in producing a preliminary survey of a piece of property I wish to develop ..... This is mainly to get a preliminary layout of the land before calling in an actual surveyor.

If you stick to your "preliminary layout" goal any of the consumer-grade units offering 3-5 meters (10-16 ft) with DGPS (WAAS) would accomplish a "ballpark" draft of your area as others have stated. It could be quite helpful in your initial planning.

[+jopasm]

The chipset used in the Oregon, Dakota, and PN-30/40 apparently has issues with WAAS support. A Garmin 60csx will probably give you better accuracy, but it's still not going to be great. Even on a good day you'll easily see errors of up to 10'. It might work for what you want, but it's not going to be incredibly accurate.

 

You're also going to need the software to manipulate the data. If you have a copy of ArcMap from ESRI you might want to look into the DNR Garmin app. If you don't you'll need some sort of GIS program to pull everything together. QGIS might work for what you want, not sure - I'm not very familiar with it. I've used a Garmin 60cx and DNR Garmin to do some survey work, the results were barely useable and not very accurate.

[The Black Pearl Crew]

Do you realize that a consumer-grade unit is unlikely to give you better than 10-20' accuracy?

I'm well aware of the innaccuracies of a handheld unit. What I need to do is identify some of the key features on the property (ie waterfall, canyon, rock formations, roads) on a survey map. Many of the property lines will be dictated by natural features. It is difficult to know at this point where some of those are located on a survey map. With survey costs at $500/lot it is nice to get a good idea of how you really want to lay out the property before a final survey. The project will probably be getting Lidar aerial mapping eventually. I am confident I can easily identify the key features and approximate property corners with an upgraded unit like the Garmin 60csx. Basically, I would need a software program that could connect the dots and calculate the area inside a polygon. I would assume that even with the innacuracies of a GPS unit you could still estimate a lot size @ +/- .1 acres. It would be nice to overlay those waypoints somehow on a survey map and draw out the property lines.

[+MaliBooBoo]

A 60C(S)x (particularly the older model with the Sirf chip) in the field in conjunction with OziExplorer in the office is what I would use. Get some really good imagery to use in Ozi and you`ll be off to the races. Ozi is an excellent GPS utility for what you are talking about doing.

[d.higgins]

I am interested in producing a preliminary survey of a piece of property I wish to develop. My main goal would be to mark out lots using waypoints and then sketch out a survey map for reference use. I definitely want to draw out the lot lines and calculate the area of the lots. This is mainly to get a preliminary layout of the land before calling in an actual surveyor. I'm new to geocaching and I've used my old Garmin eTrex legend for my first 100 finds. I am definitely looking to upgrade and want to make sure I get a unit and the software I need to also assist me with the surveying aspect. I have never used any software in conjunction with my handheld and I'm not even sure what options are available. Any advise would be greatly appreciated. Thanks in advance.

 

I have done this on a couple of developments. It worked very well. We developed a 300 acre property. The lot size had to be a minimum of 5ac. The terrain was much as you describe. Our goal was to identify the building sites, then plot out a minimum of 5ac. lot around the building site. Also lay out the roads.

We understood the limitations with consumer grade GPSr. When finished we gave the "map" to a surveyor to perform the actual survey. Or GPS lines and waypoints came out closer than we had hoped for.

This is the method used.

I took a waypoint of the property corners, the building sites, and made a track for the roads. I used UTM's.

I used AutoCad next. Starting with a blank "paper" I entered in the coordinates for the corners using the UTM's as x/y. I then took an aerial photo of the property, imported it into Autocad (scaled correctly) and used it as an overlay to check the boundaries and physical features.

Next I took my track files and imported those into a text file. With the tracks in text format I could write a script file to import my tracks into AutoCad. This worked very well.

I also took a .jpg of the plat map and made an overlay with it much the same way I did with the Aerial photo.

Now with the info in AutoCad I drew my lot lines and property corners. In AutoCad you are able to measure you lot sizes and such.

After getting lines and property corners where I thought they needed to be. I exported the lot corner positions to a text file. From there I put the property corners back into Garmin format and set out to mark property corners.

I drove lathes at the "suggested" property corners. Then gave the AutoCad "map" to the surveyor.

I also had the distances and bearings of the lot lines on the "map".

 

We are very happy with the results. And have used this method on several other projects.

 

The Software used.

Garmin Mapsource

AutoCad 2000

Microsoft Excel

Notepad

Photoshop

 

I used excel to change the Garmin format as needed. I'm sure there are better ways to do this, I'm just a excel geek.

I used Photoshop to view and manage my .jpg and such.

 

Hope this answers your question.

Doug

[The Black Pearl Crew]

Thanks Doug- I am glad to hear from someone who has tried the very thing I'm attempting to do. I'm sure you undertand the advantages of getting to do some preliminary work like this yourself. I used to be well familiar with AutoCad when I worked as an mech. engineer but that has been a while now- I'll have to brush up on that. Thanks again for your detailed method description.

Edited March 5, 2010 by The Black Pearl Crew

[+agentmancuso]

There's some detailed information on the practical use of survey grade GPS equipment on this hillwalking site. Their main concern is with height data rather, but it might point you in the right direction.

[seldom_sn]

Do you realize that a consumer-grade unit is unlikely to give you better than 10-20' accuracy?

 

Can the accuracy be improved by waypoint averaging? The OP will use waypoints to mark his corners.

[xyzee]

I'm not much on software, but I would have fun finding the most open property corner, and getting the best fix possible, under the most ideal Sat PDOP. Then use the projection feature, if the distance and bearings are known, to make a plat on the Routes Mao Page, from the waypoints.

Might even be able to start from a good controll point from somewhere in the middle of the property, where its the clearest to get the best from the Sats.

I use a Garmin Map 60Cx, and Meridian Color, for mineral/mining claims, and related, connected to an external antenna mounted on a ground plane, 19cm or 7.5 in in dia. on an adjustable pole with carrier for the receiver. Glisson says that the ground plan helps 20 to 30 %.

Attaching the pole to a tripod, allows me to average for 20 min or so, over a point, a lot easier than holding the unit over my head for that long. This is overkill for most people, but helps me a lot when in the Utah mtns in the summer. Need all the help that I can get, when the mtn with trees, are blocking the Sats when in a high mtn valley.

Might be an add on to the rest of the projuct, seeing how close the projection were.

[jmundinger]

You might check out one of these:

 

http://www.igage.com/mp/magellan_professional_gps.htm

[+Redwoods Mtn Biker]

Post-processing with a Garmin:

http://gpsinformation.info/harris/gpspostprocessing.html

[+ecanderson]

Post-processing with a Garmin:

http://gpsinformation.info/harris/gpspostprocessing.html

Was poking around, and it appears that the upm.es software that was developed only supports the older Garmin units with serial connection. I wonder if anyone has taken the time to tweak this code to manage USB connections?