Bill93
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Everything posted by Bill93
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This happens all the time and nobody does anything about it. NGS doesn't have funds to send crews out for this stuff. The "right" way is for a local surveyor to go through the NGS official RESET process to preserve a related elevation on a nearby new mark. That takes time $$ and knowledge that isn't going to happen very often. NGS officially says you should send in a destroyed disk, but that doesn't happen often either. Lots of people have souvenirs. We just hope they don't end up on eBay to encourage people to grab ones that weren't already destroyed. And then there is the upcoming redefinition of elevation NATRF2022 that should be released by 2025, after which all new work should use that, with GPS corrected for gravity variations, instead of physical disks. So the old disks will only be of use for finishing work in progress or checking historical work. Don't think your past recovery reports have been in vain. Many of the old disks were used to check whether the new datum was coming out consistent, via the GPSonBM program, so knowing which markers were still there helped guide the collection of the check data.
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Report what you see. The marker type is Disk, and Designation is TT 32 H, which is what is stamped on the disk. I'd say disk in good condition. You could also say Drill mark mentioned in 1993 also present. I have no idea why South Carolina Geodetic Survey would mention the drill hole in a report for this PID, and suspect a misinterpretation of the field notes by someone in the office who submitted the report. Maybe there was an older drill mark before the disk was set in 1934? How old is the building? I question whether a mark so near a building would be suitable for satellite observation.
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Groundspeak is removing Benchmarking and the logs/photos
Bill93 replied to Michaelcycle's topic in Benchmarking
Fox, thank you for the archive link. I wouldn't have figured that out myself. This is a huge benefit for any of us who were depending on GC to keep notes for us. I have my spreadsheet but there are a lot of other details in those logs, particularly for ones researched but not found the first time around. -
Groundspeak is removing Benchmarking and the logs/photos
Bill93 replied to Michaelcycle's topic in Benchmarking
In a quick scan of the linked page I didn't see how to find my logs. I blundered around from my profile, geocache logs, etc., and did not see a way to get benchmark logs. Please give more detail. Is this a premium feature? -
When did those orange carsonite posts start getting used?
Bill93 replied to foxtrot_xray's topic in Benchmarking
The coordinates are not always that good, but it's a place to start when nothing is obvious. I jumped in here without rereading the thread, so some advice may be irrelevant. The coords for the older marks were read from a USGS topo map in the 1960's after someone plotted the description. Sometimes changes in the surroundings caused large errors in figuring out where to plot it. Rerouted highway numbers are a major source of these errors. Ive found a mark at a creek culvert a quarter mile from the coords because that creek wasn't on the map and they plotted it where a creek did show. But a witness post is nearly always within a few feet of its mark, and it's unlikely to get moved far. -
When did those orange carsonite posts start getting used?
Bill93 replied to foxtrot_xray's topic in Benchmarking
Remember that scaled coordinates were truncated, not rounded. So if they are good the mark is north and west of them. -
The names in this old old thread bring back memories of a time when it was an effort to keep up, and a lot of good folks we haven't heard from in a long while.
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Proper Use of an Intersection - AKA 'My Favorite Movie Star'
Bill93 replied to kayakbird's topic in Benchmarking
Those are some strange encounters of any kind at those distances. What are you shooting with? -
Has anyone here looked into these? On the pro site someone is asking for any information. https://surveyorconnect.com/community/surveying-geomatics/illinois-river-survey-1903/
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When did those orange carsonite posts start getting used?
Bill93 replied to foxtrot_xray's topic in Benchmarking
A search finds this: Carsonite International was founded in 1977 in Carson City, NV, and was relocated to Early Branch, SC. I don't know if they are all made by that company or if it's like Kleenex with the name being treated generically. -
I submitted a few recoveries and pictures in October via the web form that have not appeared. At leas one had been submitted earlier using DSWORLD. Is this my unique priblem?
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Take the seconds of latitude or longitude, such as the 25.37653 in the latitude given, divide by 60 seconds/minute, and tack that decimal on the minutes, rounded if you are limited to 3 decimals. Here I get 38 21.423 081 36.299 Most handhelds and many software tools will let you set the display format, so you can enter it one way, change format selection, and see it another way.
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Groundspeak is removing Benchmarking and the logs/photos
Bill93 replied to Michaelcycle's topic in Benchmarking
Looks like it has happened. At least this forum is still here. -
Anyone have an educated guess of how much storage the entire set of logs and pictures requires?
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695 for me on GC. About 450 of them were reportable and reported to NGS, which I consider to be the more important number.
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Groundspeak is removing Benchmarking and the logs/photos
Bill93 replied to Michaelcycle's topic in Benchmarking
Those who want to be helpful, are careful about identification, and take the trouble to emulate the NGS style of report can log recoveries at the official NGS site. You can input updated To Reach, HH2 handheld coordinates DDD MM SS.S format (if it only had SCALED), and photos. You can use the category L GEOCAC group code and your initials as Chief of Party. There is a helpful guide on their site. https://geodesy.noaa.gov/datasheets/SurveyMarks_FAQ.shtml#RECOVERY https://geodesy.noaa.gov/surveys/mark-recovery/index.shtml It will ask if the mark is suitable for GPS. You can say UNKNOWN if you aren't sure. Suitable generally means most of the sky clear except for perhaps poles or isolated tree not too close. Hold your hand outstretched with little finger at the horizon and see what is higher than your thumb. Generally they want reports if it has been 5-10 years or more since last recovery OR condition has changed. Don't log it unless you have useful information to add. They don't need a dozen "me too" logs. At this point only marks with ADJUSTED or GPS elevations on the data sheet are of high interest. I think they still accept Triangulation stations, but do not want Intersection stations (towers, etc). Condition means how well the mark has held position and not cosmetic condition. So you don't have to give up the hunt. -
Dave Doyle gives a quick discussion of BM A JV3199 (NGS) (geocaching). He talked more about the history after this clip on our tour for the Surveyors Historical Societ. mloser was also there. The elevation inscribed by it is NGVD29, not the latest. https://www.facebook.com/nspsinc/videos/389659599993441/
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https://www.geocaching.com/mark/ still brings up any bench mark logs I have looked for. I have never used Waymarking. The NGS site has the latest data sheets. https://geodesy.noaa.gov/datasheets/index.shtml
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Possible unlisted benchmark in Stockbridge, MA
Bill93 replied to CelloFellow's topic in Benchmarking
It is possible it is a bench mark not submitted to NGS, but much more likely that it is not and is a property corner set by that company. Most property corners in the US are simply a pipe or rebar, often with a plastic cap identifying the surveyor or their company, but in some areas and for some clients a metal cap my be more common. I would have expected a license number, though. -
Someone has collected lots of USGS scanned data sheets in the eastern ~half of the US and made it available for FTP download. Most states are not complete, but there some are. https://surveyorconnect.com/community/surveying-geomatics/usgs-benchmarks/
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Noting that it is on private land is important. Owners change, so names may become out of date.
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Some here may find this interesting. GPS isn't everything. http://www.analemma.org/index.php/courses-events/geodesy-at-turner-farm
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https://www.archaeology.org/issues/451-2201/features/10190-rome-pomerium-marker
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What is sea level? This might help understand why a geoid model is used instead of trying to use actual sea level. https://youtu.be/q65O3qA0-n4
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NGS is working on an update to the vertical datum. Just as NGVD29 was replaced by NAVD88 and NAD27 replaced by NAD83 when much better data became available, now there will be new horizontal and vertical datums labeled NAPGD2022, but unfortunately delayed somewhat beyond that year by funding and COVID. When the new vertical datum is released, elevations will change by some amount from the NAVD88 datum values. It has been found that NAVD has about a meter of tilt across the country. Three feet in 3000 miles isn't too bad, but they can now do better. Most importantly, as we know bench marks tend to go away and you are lucky if 1/4 of them are left in your area. The 2022 vertical values will be defined as what is measured by GPS (GNSS?) plus a geoid value, so that projects are no longer dependent on having a physical mark nearby. We have seen a series of geoid updates to better model the gravity, but those "hybrid" geoids still hold the old NAVD88 elevations on the marks in the data base, and only provide more accurate interpolation between those points. The 2022 datum will change all elevations to be more self-consistent across the country, using the best new geoid model they can make without depending just on old leveled benchmark values. For this they have been working on the GRAV-D project to get aerial measurement of gravity across the country and some gravity measurements on the ground. NGS needs a tool to allow people to convert NAVD88 elevations they have to good estimates of 2022 elevations. To check and refine the conversion model, they are using comparisons of GPS measurements versus NAVD88 values on good bench marks. Most of this data is being submitted by state DOT or DNR agencies, with some from various other sources including individual surveyors or researchers with the required equipment, submitted as OPUS Share data (see map of submissions). Look up the GPSonBM project for details. I hope that explanation helps, and is sufficiently clear. DaveD can correct me if I misstated anything.