GPS for mapping cemetery

[Slumberkinge]

Hi everyone

I'm a member of a local historical society and our project for the coming year is to map out our local cemetery. Roughly 52 acres and several thousand graves. Over the past hundred years there have been several people who have managed it and so everything is a mess.

We see many genealogist who come looking for relatives and they place a gps device on the grave for about 10 minutes and then mark down the results. We'd like to use this technology but don't know where to start. About 40% of the plots have well defined borders, so we assume we will identify each plot by the corners we are certain of and then extrapolate the rest by eye. Several of us have auto based navigation systems (I have a TomTom) but we would guess it would not have the precision we would need.

Can anyone help us with information to get started?

Thanks

SlumberKinge

 

[canderson]

We see many genealogist who come looking for relatives and they place a gps device on the grave for about 10 minutes and then mark down the results. We'd like to use this technology but don't know where to start. About 40% of the plots have well defined borders, so we assume we will identify each plot by the corners we are certain of and then extrapolate the rest by eye. Several of us have auto based navigation systems (I have a TomTom) but we would guess it would not have the precision we would need.

Given the size of a typical plot, there's little chance of being able to afford a unit that will consistently place you on top of a specific grave site. That would require a commercial grade unit used for surveying purposes.

That said, consumer grade units (not including a TomTom or most other automotive units, which I'll explain in a moment) can, under the right circumstances, provide you with a fix within a circle of about 20' diameter with good certainty. On a good day, it may be better than that. You should be looking for a handheld unit that is capable of WAAS correction (uses one or two FAA satellites to correct the GPS data) and that is able to mark a waypoint by averaging over a period of time. There are quite a number of good handheld Garmin units with these features.

One major variable in the quality of your fix will be the sensitivity of the receiver on the GPS under less than ideal circumstances, especially tree cover which impedes the signal. So in selecting a handheld, you will be looking for models that specify a "high sensitivity" GPS chip. The older Garmin handhelds that are available used do not incorporate high sensitivity chipsets.

Suggestions for your purpose include the Garmin eTrex Venture HC. That one has all of the requisite features, a relatively easy to read screen in daylight, and won't break the bank.

You'll need to avoid automotive GPS units, specifically TomTom units, in general. The reason is that their firmware is designed to record positions that are "on-road". To keep the little icon of your position from straying from roads that are not precisely geolocated, these units will take your computed position and MOVE you back to the nearest road - up to a point, anyway. Wander 200' off a road, and it will still attempt to place you at coordinates to the nearest point of road. As a result, they can give you some really wrong coordinate data for off-road use. This feature is often referred to as "road snap", and is great for automotive use -- it keeps your display from showing you as having a serious off-road experience if the mapping of the road isn't entirely accurate -- but is lousy for wandering off into an adjacent field or cemetery. A TomTom will, as a result, actually provide you with "bogus" coordinate data to a nearest point on a road on the coordinate numeric display instead of the real coordinates.

Hope that helps.

 

[mikealder]

I would group the graves into small batches of around ten then take a reading from the centre point of the ten, this way someone looking for a specific location would only be a few feet away from what they were looking for. This will also reduce the number of locations needing to be recorded. Look at JOSM which I use for creating OSM data from a GPS trace, this could quite easily be used to produce a "map" containing the information you need.

One option with a TomTom is to install say a UK/ European map and select that whilst in the USA, this puts you a few thousand miles away from the nearest road (on the map) therefore negating the "Snap to road" issue that Canderson rightfully mentioned. Although being honest I think you would be far better with a true off-road style unit for this application.

An other idea would be a decent grade camera with integral GPS/ add on module like Nikon offer for their higher end Digital SLR units. This could geo-tag each grave that you photograph making the whole job much easier as all you need to do is take a picture of each grave. Post processing the pictures for the GPS coordinates and names of those burried at the location. You can find some additional information on geo-tagging pictures and how to do it with a PDA based mobile phone assuming its got a GPS receiver Here the write up also highlights some positional errors which were down to the hardware in use, I admit the windmill was a rather large subject for the picture in comparison to what you are wanting to do but the priciple of how to do this is worth looking in to - Mike

 

[canderson]

An other idea would be a decent grade camera with integral GPS/ add on module like Nikon offer for their higher end Digital SLR units. This could geo-tag each grave that you photograph making the whole job much easier as all you need to do is take a picture of each grave.

Another sweet option for this kind of work is the newer Garmin Oregon 550. Manages the geotag as part of its normal operation. The 3.2Mpix camera produces a credible 8x10 photo. Will set you back a good bit more than the Venture HC, though.

https://buy.garmin.com/shop/shop.do?cID=145&pID=26875#specsTab

They're available for about $430 retail.

 

[Slumberkinge]

That's good to know. Didn't realize that "auto navigation" specific GPS would correct location. That could have really had us wasting hours in the field. Will look at some of the dedicated GPS such as the Trex you mentioned.

Checked out the Trimble line and found that for our limited use, this would be cost prohibitive. Maybe a high end device could be rented for the week.

Appreciate the good responses. Thank you.

SlumberKinge

 

[canderson]

That's good to know. Didn't realize that "auto navigation" specific GPS would correct location. That could have really had us wasting hours in the field. Will look at some of the dedicated GPS such as the Trex you mentioned.

Yes, if you're within 150 or 200 feet of a road, all of the units they have produced for several years do this, and even the 3rd party software guys haven't been able to get around it.

Checked out the Trimble line and found that for our limited use, this would be cost prohibitive. Maybe a high end device could be rented for the week.

Yes, that's the sort of unit I was describing as "commercial grade". Great technology, but comes with a big price.

Good luck with your mapping.

 

[Cham101]

I mapped a historic cemetery. I didn't bother with taking pictures because Find-A-Grave members had already done such a great job with the pictures and the history. I didn't feel like redoing what they had already done. My map was done on a day where I was able to get good satellite reception and +- 6ft accuracy with a DeLorme PN40. I used Everytrail to allow people to transfer waypoints with a gpx file or with their hand iPhone application. For those with Droids they can use the Google Maps, you can read the direction. Google Maps allowed me to place the FindAGrave links in pop-up balloons, and also provided a way to organize an index. So far I haven't had any complaints, the folks at the cemetery like the map.

Cham's Adventures and More: Green Mount Cemetery Map - Famous People

 

[Lemain]

I wouldn't do that job with a GPS on a per grave basis. Quicker, easier and more reliable to borrow or hire some basic surveyor's kit (theodolite and/or Electronic Distance Measuring device such as a Geomensor) and plot manually. Store the data onto a spreadsheet or, if you must, some kind of relational database and then, with care and accuracy, use a non-road use GPS to define the outer limits of the cemetary. 'Snap to Road' is why Tom Tom and other road-specific GPS devices are not a good choice, as others have said. Marine and aviation handhelds are fine, e.g. Garmin. One thing to watch out for is distortion due to the cartography system -- to be of any use to anyone your cartography has to relate back to whatever 'map' the users of your data will be using. If you are planning to market this data on Mars, make sure that you normalise it to the appropriate Martian survey maps

 

[GraveDigger]

Mapping cemeteries

Hi,
Just to let you know I have been mapping cemeteries for some time using a specially developed GIS tool. If anyone would like to talk to me about helping them with mapping their cemetery/graveyard I would be happy to. For smaller cemeteries I would be happy to do it for free.
GraveDigger

 

[fiona8757]

Hi Grave Digger; My husband and I just went to an abandoned cemetery and photographed about 35 graves (out of a total of 137) and got the coordinates recorded with each photo. I was hoping to get the graves plotted out on a map somehow. The cemetery was abandoned and after a terrible tornado in 05 many trees fell into the cemetery, and then with the massive ice storm in 09 an even greater amount of damage was done. The cemetery is almost beyond recovery now. I am still editing photos and getting them uploaded to FindAGrave, then I would like to try to somehow get the map of the graves I was able to find mapped out for future reference. ANy assistance would be greatly appreciated. Rebecca.

 

[dhn]

Welcome to TTF, Fiona. Just wanted you to know that you are replying to a post made over a year ago by someone who hasn't been back here (posting) since. I hope you do get a response.

 

[canderson]

Rebecca -
Your best consumer grade tool remains as described above, especially for the price (they're available cheap now!). Using the 'Waypoint Averaging' feature, you'll get as good a fix as is available without serious commercial equipment.
When you are done recording, you can use several different mapping programs (including 'Basecamp' which comes with the 550) to plot the locations you have recorded since the Garmin will record in the popular *.gpx file format. If you have additional questions, let me know.