Re-establishing Survey Corners and Way Points?

[mapper]

The term "aerial photos" that I see in these posts when referring to GIS and Google maps is incorrect. The images that you see are correctly called Orthophotos. These are created from aerial photos or satellite imagery by correcting the image displacement caused primarily by elevation changes in the terrain. To do this accurately requires an accurate gemetric model of the ground (DTM) and accurate positioning of the camera or sensor at the moment of image capture. Kinematic GPS and a accurate inertial measurement unit (IMU) on the sensor can give a reasonable approximate fix. To refine this to a highly accurate degree requires targets on the ground, that are set and a high accuracy survey to determine position and elevation i.e. a geodetic survey performed to provide a precise location. The higher the accuracy the higher the cost to produce.
Orthophotos are produced by some state agencies and by contractors for federal, state and local agencies under contract. The contracts will include pixel size, and positional accuracy.
Depending on Orthophotos to give you a highly precise position on property corners is very risky if you do not know the accuracy standards that they were produced under. Even then they are not always error free. I have found errors uo to 100 meters when the accuracy was supposed to be 2 meters.
Prior to retirement I worked as a professional photogrammetrist for 35 years.

 

[California]

In my state, many older surveys were done using metes & bounds (distance and compass bearing) rather than coordinates. I use this program to draw deed plot maps from that data:

Metes and Bounds Plotter | Deed Plotting | For Windows, Mac and iOS

Free Deed Plotting Software. Metes and Bounds Plotter. Legal Description Plotter.

www.tabberer.com

The plot map can then be used as an overlay in Google earth to get a good idea where property lines are. Its no where near as accurate as a survey though.

Thanks! I bookmarked that and will see what it shows me. It looks to be a solution to what I asked above: start from a known pin and locate a corner that is about 500 ft away on a Google Earth image, that gives me an idea where to look on the ground.

 

[dodge man]

Mapper, I’ve done the control work for aerial photos several times over the years. I’m not sure how or why, I suspect it’s improvements in cameras or the gps they use with the cameras, but it seems they need less or sometimes no ground control. For example the nearby landfill was flown every year, they needed good elevations so we always did targets.

On the other hand the GIS for our county we did ground control the first time the flew it about 25 years ago, but since then they haven’t done targets. Elevations are less important for that work though.

 

[mapper]

Mapper, I’ve done the control work for aerial photos several times over the years. I’m not sure how or why, I suspect it’s improvements in cameras or the gps they use with the cameras, but it seems they need less or sometimes no ground control. For example the nearby landfill was flown every year, they needed good elevations so we always did targets.

On the other hand the GIS for our county we did ground control the first time the flew it about 25 years ago, but since then they haven’t done targets. Elevations are less important for that work though.

It depends a lot on what the accuracy standards are for the product desired. When I retired 6 years ago airborne GPS/IMU data was good to around a half a meter. DTM data has also been improving, when I started in photogrammetry 40 years ago we had to produce the DTM from controlled photography. This was done primarily for resource grade 3' pixel imagery. Aerotriangulation of a block of 100 images took a month or better start to finish. DTM collection was about 50 8 hr days for that 100 images. Ortho production was also a slow process which utilized a very expensive machine ($1000000+) to produce, there were probably less than 10 of these at any time in north America. The cost to produce these was astronomically high.
By the time I retired 100 models of AT took about 8 hours (+10 or so hours of computer processing time),
DTM was being collected using airborne LIDAR, and Orthophoto production was less than an hour per image. This was done on a high end PC rather than a half million dollar mini computer and million dollar optical plotters!
So yes the quality and accuracy of Orthophotos has gone way up and the cost has come way down. But all of what I said in my first post still applies, you have to know what the accuracy standards are before assuming that the location on the Orthophotos is the absolute truth.
Bottom line, a licensed surveyor is needed for a good and legally reliable boundary survey.
Also it should be noted that the original GLO (government) survey in the western states that all property descriptions are based off of, were not perfect, every section is not a perfect square mile, assuming so will get you in trouble. Another reason for a licensed surveyor.

 

[dodge man]

My experience in Illinois is the original surveys were done to an accuracy of around 1 in 100. Sometimes better, sometime worse. This means for every 100 feet measured they were off a foot. They did my part of Illinois around 1816. Just about anybody can go out with a 100 foot cloth tape and do better than that but that was the standard of the day.

As you move further west where the started using a transit instead of a compass to run line the accuracy improved considerably.

 

[mapper]

Here in Washington state they used Burts Solar compass. Mix that with mountainous terrain, heavy old growth forest and lots of overcast days, there were some kind of sketchy surveys, the standard was 1:100.
I came to photogrammetry from a cadastral survey crew doing a lot of GLO retracement surveys. I continued retracement work in photogrammetry by marking the calls to scale on clear acetate and then plotting the calls photogrammetricly and finding a best fit, I would then pass search positions to the field crews to locate the original corners. Part of this was reading copies of the original notes, they were at times some very interesting reading. My favorite was a description of a valley with hundreds of snakes hanging in all the trees, led us to wonder about the mushrooms they may have found in the previous valley.

 

[Jstpssng]

My experience in Illinois is the original surveys were done to an accuracy of around 1 in 100. Sometimes better, sometime worse. This means for every 100 feet measured they were off a foot. They did my part of Illinois around 1816. Just about anybody can go out with a 100 foot cloth tape and do better than that but that was the standard of the day.

As you move further west where the started using a transit instead of a compass to run line the accuracy improved considerably.

100 years ago they were using a staff compass and steel tape. Land wasn't really valuable until it was settled and they were covering a lot of ground, sleeping in tents and working in all kinds of weather.
I used to lay out precommercial thinning blocks with a hip chain and Suunto hand compass. The minimum error allowed was 1:250.
Somebody with your experience could probably get it that close pacing.

 

[dodge man]

I used to be able to pace a 100 feet with in a couple of feet, probably not so good any more.

Illinois was laid out with a two pole chain, 33 feet long. This is really a half chain. It was actually a link and bar type chain not a steel tape. Most of the sections in Western Illinois are oversized. A half mile runs around 2650 to 2670 feet normally.

 

[mapper]

I think we may have stolen this thread a little.
When I graduated from college my first real job was with a timber company, working on a survey crew. One of the office engineers (by title not education or license) was a 65 year old man who started in the woods at about 15 years old (1926?). I worked with him in the field a few times laying out logging roads. He was really amazing, absolutely indefatigable, hard for my 22 year old self to keep up with. With nothing more than pacing, an anaroid barometer and an abney level he could spot a mile of grade in less than a day. We would start at the end of the existing road where he would zero the barometer, then hike to the location of the next landing, counting paces. He would then calculate the grade from the paced distance and the elevation change on the barometer. Work our way back to the start point marking grade as we went. If we missed grade at the end we would adjust and remark all the way back. All this was done on 60-80% slopes with numerous gullies and small streams and at times dense brush.
Needless to say it was a humbling real education for me with my AA in forestry.

 

[Rockbadchild]

Neighboring parcel is for sale for the first time since 1955 to settle the estate and there appears to be confusion among the prospective buyers and agents as to the location of our shared property line...

I have not been able to find the pins shown on my property's 1989 survey...

The street has been repaved and 5 years back the city dug up and replaced city sewer line running under shared property line taking out the pins.

Realtor suggested a survey of the property for sale and wants me to participate which I declined.

I got to thinking wouldn't it be much less expensive avoiding the cost of a survey calling the original company out to find the pins?

Any tips on how to approach the survey company to find three pins on a straight line?

A new survey here tends to run about 5k.

Is the best shot sticking with the original surveyor to save on cost?

original surveyor of not will be the same cost if not id be surprise especially since it was that long ago … can you get your hands on a metal detector ?