evenfall
-
Posts
788 -
Joined
-
Last visited
Posts posted by evenfall
-
-
Paul, And others wishing to use Electronic Measuring devices.
In your case I am assuming you are using a product from Calculated Industries Paul?
The Physical problems associates with Sound and Air Pressure can affect accuracy. So can extraneous noise and indirect reflections or sonically diffusive or absorptive materials. To aid with the combat of "mystery force" on items like this it might be useful to carry a small piece of Glass with a reflective adhesive tape along to use as a reflector. The Principal is similar to the ones used with EDM in Surveying. We use a prism mounted to a prism or range pole as a target when we measure angles and distances and the prism or reflector assures we get the measured info back to the instrument accurately. We go together with both measurements at once to accomplish a trigonometric leveling and positioning. If you have a light based tool your self, the same principle should work, if you are using a tool which is truly Sonic, the hard glass should help accuracy by reflecting the sound directly back to where it came, and a quiet environment when attempting to use a sonic tool may help too.
In the end the physical properties of light are much more stable than sound if that helps anyone in a future purchase.
Good Luck!
Rob
-
Interesting. :-) Good thoughts Geo, Nice Idea!
Giving Credit and receiving Credit instead of taking it is so much more rewarding anyway. And is so much more humble.
Thanks Geo, that was cool.
Rob
-
Black Dog,
The Cairn can be useful if it is needed but it is mostly a relic from methods of old. Back when big wooden or aluminum towers were used, even a small tower could be erected over a cairn if it was in a place which could be used for an instrument setup. We have not used Bilby towers in Survey work in a long time. Close to 20 years now. Most often the Cairns were often built in a high place, and the survey was treated similar to a landmark station. Angles were turned on them rather than from them. Sometimes they were good for the one time. The numbers were attained for geodesic calculations and not used again. Others had stations monumented near or next to them to accommodate further use with modern instrument set ups.
Today, If I needed to use a Cairn, I would turn angles on it first to see if it is accurate enough to trust at the accuracy is was said to have. In other words, I doubt it would be as accurate as it once was. Poles decay and other natural forces may have acted upon the Cairn since it was erected. The Pole held by the Cairn was what the angles were turned on. Some cairns do not have poles and some did but don't anymore and some conceal station discs and... The list goes on. A GPSr set to WGS 84 would never reveal any of the former accuracy though as you would actually be a meter off in the first place, as that Datum does not apply to Survey in N. America. I doubt any mark duster could certify the quality of the station beyond being still there. The Numbers we have in the datasheet were and are still important to geodesy and can be used in theoretical calculations, but the condition of the original accuracy any cairn could claim today would be relatively questionable in my thinking. I would look for something more stable. It's probably just fine for a find at geocaching though. I wouldn't big deal a cairn to the NGS. A station disc is more to a Surveyors liking.
Most of todays instruments, are very productive, along with the expectations of same from the crews. Unless the point was really needed, I doubt most of us surveyors would bother with them. We try to avoid turning angles on landmarks as much as we can. With a GPS Setup we can't turn angles at all. We have to be centered over the spot. So much of the work requires higher accuracy now.
Rob
-
WxGuesser,
Your GPS is defaulted to the WGS 84 Datum, and though this too is an earth centered Datum that uses the same satellites to derive location, it uses a different location to locate its theoretical earth center than NAD 83. The difference is about one meter.
WGS84 will get you close, but it is best to set your GPS to the proper Datum for hunting and discussing the locations. The most appropriate Datum used for discussing horizontal locations in North America is NAD 83 followed by NAD 27. WGS is as not highly accurized for North America as the North American Datum is. These benchmarks are in part the basis for the NAD 83 Datum.
When dealing with vertical location, the NAVD 88 Datum is the most accurate Datum currently in use, and superseded the NGDV 29 Vertical Datum which was in use prior to it.
Most importantly, there is the FAQ Page and a great deal of information already written about this here at geocaching. Please feel free to play with the functionality of the forum are read through many of the threads already posted here at the Forum. There is a wealth of info already here.
Enjoy,
Rob
-
Nope, the NAD 83 coordinates are the only coordinates appropriate to Benchmark Hunting. Any other Datum is the wrong Datum.
Happy Hunting,
Rob
-
Hi John,
As you may be aware, I recently started a thread in the general benchmark Forum. I spoke of Camps and as you may have guessed, I am in one of them. I reckon you may be in a different one. I like to think of myself as being in the third one. I think I see you as a person who would like to place limits, I am someone who would like to see less limits. I am all inclusive, I like the ideas of share the road and space enough here for all.If it were not for the NGS and Their data, you would have no game to cherish and enjoy. Since you hunt Benchmarks more than you GeoCACHE, I'd say you too ride just a little bit for free eh? Fortunately, I want the best for you and those in your camp. I Have proposed a tenable solution for this dilemma, and I would love to see you show support for it. I am asking for this in part to accommodate us both. Your Camp and Mine.
I am not interested in limits. I am also all for Geocaching increasing it's Market Share and I believe it is possible for them to create money making schemas from benchmarking. In fact I have been working to accomplish just exactly that. But it is not my business, It belongs to someone else and so I cannot act in it's interest to create these possibilities. (care to guess why Benchmark Hunting has not been included in the means of bringing money in, though it could have been some time ago?) I can only offer suggestions and support. Perhaps in time Geocaching will increase it's profitability from the Benchmark aspects of it's business. I am all for it.
Are you proposing all those people who want to hunt Benchmarks for the NGS go away? Many new people have come to the Forum since the first of the year with questions and the desire to help out and have fun. Many want to do NGS recovery, and I feel it is right minded to help them as they ask. Are you saying that you feel that they are not welcome here and that you feel that the way they want to hunt for benchmarks is inappropriate to the way you like to? I think I see the possibility of NGS recovery as a part of the Benchmark Hunting FAQ John, and therefore those who want to discuss this in the forum are within their right to do so.
I am just trying to clarify what you want John. Myself I would like to see all inclusiveness and I feel we can share this space and get along, but I think I have a workaround. If the workaround does not come to pass, I feel we all can still coexist. Are you saying that People should not play this game in any other way that the way you like?
I feel we get what we negotiate John, and so I am Negotiating.
Rob
-
WxGuesser,
It is absolutely possible and has been asked for many times in the Pinned topic at the top of the forum entitled Ask Jeremy... concerning things and functionalities people would like to see. However this is something that has not been made available yet. Since you ask, Maybe many other people will post to this specific thread as a show of support to Jeremy for this often requested capability. Perhaps then, he may undertake developing it. Currently there are no membership perks that are provided to the Benchmark hunters.
Squeeky wheels you know...
Rob
-
Limax,
What I am proposing is that a forum be created here at Geocaching for the purposes of discussing the recovery efforts dedicated to finding and reporting the Survey Markers to the NGS. A hopeful way of keeping most people happy most of the time.
The come and go of Hunting for Survey Markers often becomes technically involved, especially when trying to do so with the desire to report the findings to the National Geodetic Survey, which is the agency that monumented these Markers and keeps the database for them. A problem often arises between two camps here in this forum. There are those who want this forum to be about the game of hunting Benchmarks, and only for the purpose of playing the game here at Geocaching. They would prefer that the discussion of NGS recovery take place elsewhere or perhaps not at all. Some have come forth and made statements that they would prefer this forum be only for the purposes of playing the Game, and Not about NGS recovery. Others have claimed that the Purists are too technical and are too imposing with their scrutiny so as to take away from the aspects of what they want from the game. Simply put, some just want to enjoy the game without the technical discussions. I do not blame them for their feeling. Different strokes for different folks, but with only one place for us all to come together here at Geocaching, we must coexist.
In the other camp are those who have many questions which require answers which go into the technical nature of surveying and other similar concepts in order to play the game they want to, which is to report what they find to the NGS so that the Database can be updated. The Updates to the data that the NGS keeps is largely maintained on a volunteer basis by those who choose to do so.
There is probably a third camp who is not bothered either way and think it is all good. Some may actually feel strongly either way or feel both, some may evolve from one to another or both or neither. My Hope is to become more accommodating and inclusive of all if we can, and if Jeremy agrees. As much fun as possible for all, no matter their brand of fun.
Communication with the NGS is already happening here in this forum. This proposal would not facilitate this more so than now as the NGS is already very welcome here, but it would facilitate all who want to talk tech, and those who do not, by making the topic more specific. What I am proposing would make some of the discussion in this forum more Topic Centric. Those who just want to play the Geocaching Game version of Benchmark hunting would have a forum which is set forth for the purposes of discussing the Hunts, showing the pictures and congratulating others on cool finds, and hopefully would attract people by the fun aspects of the hobby. Hopefully people not interested in NGS recovery would not feel put upon by those who love to do it. The New Forum, Hopefully would be hosted Here at Geocaching and would be for the hobbyist who wants to take the game further into the technical aspects of hunting, finding, problem solving, error reporting and the general discussion of the Surveying Aspects of these monuments along with the liaison with NGS so as to go deep and discuss the matters we do without it becoming a bother or a drain of those who just want to play a game. Of course the photos and the congratulations would also be welcome in either forum but the deep discussions towards NGS recovery would be most welcome in one forum more than the other.
As things currently are, the potential for a newcomer to the hobby to ask a simple question about the game is sometimes misinterpreted and the answers range from simple answers to an involved discussion about how to recover the mark to the NGS and is interpreted as that they ought to. I contend that there is no ought to, yet in the eyes of some beholders I am told they feel put upon. I am looking for a way to relieve this feeling and promote the fun for all the ways we all enjoy the hunt here. If such a clear way of asking were currently possible, then if a person were to be in the NGS Forum, they are looking specifically for an technical answer, and those in the Benchmark game forum would answer questions about playing the game, geocaching style. It would clear up the question as to the type it is and the kind of answer desired. Of course all people would be welcome to post in all the forums and participate in any way, it would just be more clear to all what in fact they should expect to be discussing in the appropriate forum for the questions at hand. I am looking for a way to accommodate both Camps and a way to give the NGS recoverers a Forum similar to that which was given the USGS National Map. I feel the recovery efforts geocachers make to the NGS is important, and merits it's own space. I know the NGS greatly appreciates the geocaching efforts. I hope others share this feeling. There is a good deal more discussion about NGS recovery here at Geocaching than there is for the USGS National Map.
For the most part, things run pretty smoothly here, and yet there are ways we could run smoother. it is a simple matter for Jeremy to create a new forum, and he recently demonstrated this by starting a special forum for the USGS National map, a topic which had been formerly being discussed in this Forum Space. He has also started Special Forums for other Topics as the need has arisen over time. The NGS and their Station Data are what enable us to play this game, and it seems fitting to have a space to discuss the return of the favor, by those who elect to report what they find or not to the NGS. The recovery to NGS is a different animal than the game, and cross exposure to both sides of the game will still happen, in fact it is really symbiotic, you almost have to choose not to participate in some ways just as much as choosing to. Both ways are hand in hand yet at the same time, elective. My Proposal is not one which would divide us so much as it would just more clearly define that which we are discussing as based on the expectations of what we want to talk about. Game or NGS Recovery. It would remove animosity and direct the topical content towards the desired topic without the intermixing of the two, which has been shown to cause tension and confusion amongst some. Though it would be a separate place, most of us would likely post in both forums and direct the more technical questions to the new forum, and I feel most people would find the forum on their own, as it would likely be on the forum list and found by all who frequent the list as it is. That is how most people find all the forums anyway.
I hope this helps clarify my thoughts and please feel free to ask any other question that you feel I may not have adequately answered. Just as importantly, I posted this topic as a way of finding out if there are others who feel as I do and would support having a new, separate forum created here at Groundspeak/geocaching, for the purposes of discussing the recovery of survey markers to the NGS and Technical Survey talk in general. So please, If you feel in support of my proposal, feel free to post your support in the thread. If you don't then please feel free to add your comments as well. Thanks!
Rob
-
LittleBlue,
I was unaware of the tidal pool, But in my experience it looked like it could have been an anchor at first, as we generally do not slather sealant around a survey marker in the manner that one had been, and without the new picture I mistook the marker to be monumented vertically rather than horizontally. It is likely this is a tidal station, but there are no markings on it and there is the bump at the center of the Monument which isn't a common type used by the NOS at all times. This one is not ordinary, though there may be others like it, and most usually there will be stamping on the station if set by the NOS or CGS/NGS and this one has none.
Though there is no road at the location, the rocks falling in the water can become hazards to navigation in the water as well and that would be why they would anchor rock near a waters edge. While it may not be the case this time, I just offered this as a possibility. The location near a tidal pool does make it seem less likely. Hard to say. Deception Pass is a Beautiful location and there are a number of geocaches and benchmarks near by!
Enjoy,
Rob
-
Maybe Jeremy will Design and make available such a T-shirt and market it here to all those who want one. Motto on the front and logo on the back, something like that... Ya never know, It could be a cash cow! Maybe use the proceeds to develop other cool Benchmarking products and services!
Rob
-
Hey All,
I have a proposal which I hope many of you, both Benchmark Hunters and Geocachers, who are both either active in the forums as a poster or a lurker will feel is a great idea. It is my hope that you please take a moment to weigh in with your thoughts on this topic.
For some time now I have been aware of the different kinds of ways we all can enjoy the hobby of Benchmark Hunting. Though Groundspeak and Tennessee Geocacher, as the forum moderator, have been very hands off regarding the wide range of discussion that occur in this forum, I have been feeling we as an online community could perhaps be a bit better served if there was an additional forum added for the purpose of discussing the recovery of these survey markers to the NGS.
First, though this forum is currently handling all things Benchmarking, we have over time evolved into a group who enjoys playing this game in more than one way. In the most basic of all ways, there is the Gamer, who wants to find benchmarks and claim them here on the site. There are some who just want the Game, and are uncomfortable with the discussions about recovering these to the NGS. Sometimes they have questions about how to better play the game but are uncomfortable about a pressure they perceive here to report to NGS and the high level of accuracy and scrutiny required in doing this as well as it needs to be done.
Second there are the people who enjoy recovery to the NGS, just as they enjoy the game as well but want to play at the level that the high scrutiny and different recovery rules of the NGS require.
Because of the differences in the way we can play this game of benchmark hunting, it seems a good fit to have both a forum for the game, and a forum for those who prefer doing NGS reporting in addition to playing the game.
I could go on with positive reasons to add an additional forum, but I would really like to see what others think. Please feel free to weigh in on this Topic. The Hope Is that Perhaps Jeremy will see our support for this Idea, and create such a forum.
Thank you for your time.
Rob
-
Little Blue,
I am very familiar with this area. I have spent quite a bit of time working on both Fidalgo and Whidbey Islands in my career.
There are a number of different methods used for doing so, but is could be likely this is a rock anchor, attempting to stabilize a rock outcropping which is loose and in danger of becoming a hazard to navigation. Deception Pass, while very beautiful, is a very dangerous area to navigate as the water when the currents are running are as fast as any ever seen in salt water.
Just a ways north of there up the coast is State Highway 11, otherwise known as Chuckanut Drive. On one occasion I was involved on a job up there where there had been a rock slide which cut loose and covered the road below. If you click on the link you will see a picture on the front page of that site which is representative of the look of the area. What you don't see is that about 150 feet below that road there lies right at the shoreline the BNSF Railroad single track mainline spur which runs from Everett Washington to Vancouver British Columbia. It is a pretty busy stretch of railroad.
After the slide, we surveyed so as to give the engineers a comparative analysis to study the movement of the hillside. This is a very unstable hillside and this often happens during wet winters where there is a lot of water saturating the hill and then a freeze happens. Functionally the water works on the rocks primarily in 2 ways. First the water will act as a lubricant between layers which can lessen the adhesive properties between the rocks and cause them to slide, and if the water freezes, the expansion from the ice can crack rocks and cause further fissuring and fracturing that will often leave the hillside undetectably more stable.
Often one of the engineered solutions to help mitigate some of the safety hazards is to drill the rocks and place anchors. after the anchor is placed, an attempt is made to place a lot of an adhesive sealant around the anchor so as to prevent water from getting in to corrode the anchor or further fracture the rock.
The object in your picture looks very similar to the anchors I have seen placed for accomplishing this, especially from the liberal amount of sealant applied around it. It is true that it could be something else as well but I thought I would offer this as a possible option to consider.
Of Note, Chuckanut Drive is currently closed due to yet another rock slide. In the Deception Pass area, one of the earliest Monumented Stations in the Pacific Northwest is available, Monumented in 1854. Deception Reset A boat will be needed to recover this station.
Rob
-
Kiss my Benchmark.... Hmmm.
Anyone else see a T-Shirt Opportunity there?
Rob
-
Hi John,
I considered that when I mentioned my workaround. A lot of cool functionality would be and is possible for the benchmark hunting community here on Geocaching, alas, it has been ages since anything has been done. Apparently no one is "Workin on it". In any case, as time goes by the data here on this site will continue to age and become more stale, and currently there is no easy way to refresh the geocaching version of the NGS Data. The Benchmark Hunters have been seemingly orphaned for quite some time now. Though you can click the link on the Geocaching site to View the NGS Datasheet, this is a 5 year old datasheet and does not contain the latest recoveries and updates as seen on the NGS website. The link does not link to NGS itself. Just an archived copy here at Geocaching.
As I have looked through this thread from time to time I have seen a number of opportunities which could be taken by Groundspeak to enhance this aspect of geocaching and market them as "Niceties and Conveniences" which could be offered to paying members. Of course the symbiotic nature of accomplishing some of these would mean that Benchmark hunters would gain access to handy functionalities and Groundspeak would have a few carrots to toss in front of Benchmark hunters to encourage paid memberships. I see Geocaching as being able to add paid memberships from this aspect of it's gaming business, but I unfortunately don't see them taking advantage of it. I see a lot of interest, as well as some disenchantment from the lack of response to requests, and some of the people who don't Benchmark hunt could benefit from having these conveniences and may then choose to start hunting them. Again I digress. Nothing much really ever seems to come forth from the requests on this thread.
While you are likely correct in your interpretation of what Buck was asking for, My thinking was a way to give him similar functionality with frankly, better, more up to date info. In addition, it was something he could start using immediately, if he finds it convenient and useful. Maybe someone will get around to some of this stuff we would like someday, but in the meantime, we have to use what we've got, and I am all for bringing any tool to the table that works and is helpful.
Thanks John,
Rob
-
BuckBrooke,
The capability you ask for is already available on the NGS website. It would be a convenience, but perhaps redundant to do it here. Besides, the NGS website offers the most up to date information, and it may be much more helpful to most people to have the latest data. Further, the NGS site offers a number of search capabilities that the geocaching site does not have. Using both sites all at once seems to
You can access the information you are looking for, Here:
http://www.ngs.noaa.gov/cgi-bin/datasheet.prl
Enjoy,
Rob
-
Neweyess,
Though you may only be doing this as a recreational hobby and for fun, and maybe you have no plans to report what you find to the NGS, I would recommend when hunting in an urban area, and in these times to take the PID of the mark(s) you are hunting, and go to the NGS website and print out the latest copy of the NGS Datasheet to take with you, feel free to staple the multiple sheet ones. Carry it with you. When you are asked just tell them you are a volunteer who recovers Survey markers for the national Geodetic Survey. It is a plausible story, and not a lie. You have the very data to corroborate your reason for being where you are and doing what you are doing in your hand or clipboard. That is an official datasheet no matter what computer prints it out. And most of all, the NGS recovery efforts for these stations is largely done be volunteers.
In any case it is official enough to be legitimate, because it is legitimate and most basically is true. You are recovering a survey marker using NGS data, But stick to the real datasheets just to be on the safe side. Most people don't really care if you are searching for a survey marker. If they grill you, you have a completely legitimate answer.
Besides, what is to say the person grilling you has any more business in the man in the moon to interrogate you? You could have said, That fella with the camera didn't look like a terrorist eh? That's funny, I was thinking the same thing about you! :-D
Rob
-
Sounds good Paul, But hopefully you will establish Rapport with them for yourself someday as well. You never know when you may have a question or an answer and you already have the right person in the rolodex. I know it is like cold calling but it isn't that bad.
In addition, you never know when they may call on you, or ask your trusted opinion about a local knowledge situation. It is nice to be considered a local expert. Good contacts are always good to have! Paying them a courtesy call can open a lot of doors. Get to know as many as you can!
Rob
-
Nice investigative work Paul. I enjoy working stations like this.
I am thinking about the condition of the one in the sidewalk without markings... Without running it all down myself, was it a brass disc or of some other type? Do you suppose foot traffic has worn off the stamping or was there never any stamping? No matter really, just curious. I see different kinds of wear on these myself, and I often wonder what it has been subjected to down through the years. When you think about it, it is amazing how well many of these hold up based on all the different places they are placed.
The condition of the pavement you mentioned in the traffic circle has me thinking. I am saying this specifically to you because I realize that you do enjoy reporting your work to NGS. For others who may be interested in these thoughts that is fine too. Anyhow, it is likely there may be patching and or paving operations to be performed in and around this traffic circle soon. Sometimes, if you like, it is worth contacting the state geodetic advisor and let them know you recently worked these stations. Let them know about the condition of the road and the potholes you found the stations. Check the Datasheets as you refer to them and Identify the station as HARN and/or what the quality of the survey on the station is. Mention that you are concerned that paving operations in this area appear as though they could happen soon and if there is any particular agency that they would recommend that you contact to alert them to the presence of the stations in the roadway.
Now you could just contact whomever you feel is responsible for maintaining the street, provided you can learn who the correct individual(s) is, yet many times you are just some person calling and you never get past the call screeners as you have no name to ask for. It winds up like the plot to kill Batman... But the Geodetic Advisor knows who they are, and getting to know the advisor is cool, as you may work with them again. Establishing rapport with them is something that will help build a future relationship, and they can help direct you to the right people, give you names and phone numbers etc... You can develop a few good relationships in the process and may work with them again. Then when you call the municipality you can ask for the right person and mention that the State Geodetic Advisor, "John or Jane Doe asked that I pay you a friendly call and let you know what I found..." Yada Yada. It helps open the right doors, establishes rapport and credibility, and calls attention to stations which may be obscure, otherwise overlooked, and perhaps in harms way.
Just a thought. I have found that many municipal managers and others in the Road and Street Business are happy to hear what you found, as protecting any existing survey is something they are interested in having happen.
For those who just hunt Benchmarks for fun, these are just variations on the theme, but I am not suggesting that anyone should do this, unless they would like to.
Again, Nice Hunt!
Rob
-
Yup, Got one like that. Got a bunch of people who seem to think it is still there too...
SY4578 SEATTLE KINGDOME FS R.I.P. March 2000. Imploded and made the biggest dust cloud you'd ever want to see. Then the pieces were crushed into gravel like fill material and hauled away to a land fill project. The Flagpole was damaged in the implosion and was scrapped. Used to be smack dab in the middle of the Kingdome roof. There is an open air football stadium built in it's place now. This PID has been destroyed and removed from the official NGS database.
PS, It is a not found for geocaching... Destroyed will work too. :-D I do read however that some who think they can recover it still see it there as a find. Hmmm I think the prescription on their glasses is due for an update! That and a little time off for a good rest after a doctor visit or two!
Rob
-
Bicknell,
You probably realize this, but people in the photo is something the NGS would prefer not to see. They want a close up of the mark and an area shot with the mark in it. In your photo, It would be helpful to walk around to the other side of that road sign and take the picture while attempting to have the station actually be seen in the photo, then white out part of the lower part of of the pic with a photo editing program and say something like PID HV3506, Station K 91. Looking Southwest. This way the future user knows where to orient themselves with your photo. It could be useful to add the GPSr Coordinates to this Photo in NAD 83 D/M/S Format so as to improve the scaled location as well. Again, Please use the D/M/S format so we don't have to field convert. D/M/S is the proper convention for NGS. On a horizontal control station, putting the station coordinates on the photo would not be necessary, as NGS control on those if far more accurate than the GPS any how. If you do however find that last statement to be in error, again do not attempt to give it a number, rather, contact NGS and let them know that you may have found an error and let them do the calculations.
If you submit a photo they cannot use you may not see it included and they may email you and politely ask to see if you have one without a person in it. Taking this one step further, this is meant as no one should be posing for the photo. If you are shooting this photo in a public area and having people in the photo who are not posing is unavoidable then that is different, and if you make note of this to NGS when you email it in, they won't have a problem with that.
Being that GPS birds are not geosynchronous, they move in their orbits much in the same way we would think of the graphical representation of an Atom. A few sparse trees are not going to be much of a bother but heavy cover can slow GPS down. We do have ways to work with GPS in heavy cover as well, if we know we need to prepare in advance. But that is not important to this situation, we need to assume that a GPS instrument setup can work from the station, or not. If you are standing there and your GPS is working great the it probably will for the Surveyor, If you are losing your high accuracy, it may be a problem for the surveyor as well. In the city, amongst very tall buildings it may not seem like it but that is not a clear view of the sky. Though pro grade gear has very powerful receiving ability, it can be difficult to get a good lock, and the closer to a building, the harder it gets. Yet there are Geodetic stations in cities which have not been reported for GPS usabiliy. Your GPSr can be a good indicator for this. If you have good accuracy, it is likely good. A 50-100 foot lock may be poor, but it may also have to do with where the birds are in their orbits during that time of day. I would say that at Noon on any given day, you have a better chance of properly evaluating this than say, 5 PM. Bankers hours seem to work best here in North America. If you can't get a good lock, it is likely that Pro Gear might, but maybe not either. But that is a good baseline to make a judgment call from. There can be a lot of factors that affect it but most basically you wand a reasonably clear view of the sky.
The NGS Program for submitting updates will ask about any station which is submitted good or poor, it will not know if the station is a landmark. Most generally Landmark Stations were optically intersected points which were never occupied and likely cannot be, so they would fall into the category of not being usable for GPS observations.
For those who just want to play the game of benchmark hunting here on geocaching, None of this really applies to you, all you need to do is claim that you found it, by reading the station itself, and submit a photo if you like. You have no obligation to report your findings to anyone. Not the NGS, Not even here at Geocaching.
Rob
-
Regarding reporting for satellites...
This is a very useful update. I may leave the Office with a GPS Set-Up and if I can't see the birds on a specific station, that ain't working. It is good to know in advance that I should take optical equipment rather than GPS to work a certain area, or not.
I recently reported a Triangulation Station as Not good for GPS, But in the narrative I added that during the winter the Station will work for GPS. The Station has many Deciduous Trees that would obscure and hinder the use in Summer when it would more likely be used. I felt it better to say it 'is not usable' but, with a note as to what the deal is rather than an 'Is usable' and have someone find it was a waste of time to try during the wrong time of year. I also made mention of what areas could likely be surveyed from this position, and which directions could not due to optical obstructions.
Just food for thought on how an update could be made.
Rob
-
Bicknell,
I think your sentiment toward reporting seems a good fit. The NGS would prefer no more than one report per year, however if the reporter on the same year has a different claim, such as they reported it good the you came along and found that the area was made into a strip mall and the station was lost, then that kind of a report is in order. I would never be unhappy to see a geocacher's update in the NGS Database, and the NGS has provided an agency code for geocachers who wish to use it, the code is GEOCAC. If you file with NGS using that code, credit for the filing on that update will be given as Geocaching and you may also choose to add your initials to the filing in another box on the online form so it will show that you filed the report. 150 years from now this Data will continue to be important and your initials will be read by someone looking for a station you recovered or updated 150 years before. Again, this is of the volition of those who choose to do so, I am not advocating that anyone should or ought to.
On the Job there are many times I could or could have submitted a report to NGS for a station I used, but again in many of those cases, there is nothing I could say that would improve the datasheet, other than to freshen the latest date seen. So Like Kenewah said, many of us in the industry use these frequently enough so as to know the location. I am saying I personally know where the ones I use frequently are, (and I have reported many) but I cannot have familiarity with the stations another Surveyor or Engineering firm uses in their area so what we have is a sort of Local Knowledge thing going. We have been to them many times but what someone else is doing is not known to us. If I wind up needing to survey out of an area I usually am not so familiar with, then the onus is on me to brush up on the area and wish that another surveyor had submitted a fresh update for me. Further, a GIS may already include the data for the station which was previously added to the GIS which is controlling the Job I am to survey, so I should be seeing design results which match. In addition to the NGS Control, Many Municipalities and State DOT put in a lot of their own stations, which are not NGS, but are based on NGS control, and this is a matter of convenience to the surveyor, so as to have more control and in handier locations. Since these are calibrated to NGS geodetic control, the need is not always there to chase an NGS mark unless we specifically need to tie directly in. Of course in areas of no other control, the NGS control is all there is and it is likely reported on more frequently as well.
As an aside to this, the NGS database has not always been available on line. It was a bit more of an undertaking to file these reports in the old days, and it was also a good bit of paperwork to deal with just keeping up with all the control. To add each surveyors office had to maintain their filing cabinets of control... As you can see, Geodetic Control is but one aspect of survey, and it is quite huge unto itself. Add all the other types and you can see that there is a good bit of paperwork going on, and this is just the aspect of maintaining data, I am not touching on the various engineering, property and title, court and treasurer filings that are Legal derivatives of survey information.
Yes, Surveyors could be better than they are at reporting these, and it is for our own good to do so, but I would imagine geocachers really would have more time to flesh out a tough one, whereas a Surveyor would need to keep moving to find one they can use. As a so called Professional, I know I can always improve things for myself and everyone, yet human nature tells me that the job at hand is about finding rather than not finding because Once I find a station I can use, my Survey becomes about the project I have to focus on and it is just a part of what needs done, so the ones not found are likely forgotten or back burnered and not returned to. My Bad? Sure it is, but it happens.
As Hunters here at Geocaching, our prime concern is to really try hard to find something and time is not a factor so we can quickly see the value in the difference. We can keep trying Taking as long as we want or need until we are sure it is found or not, and this time factor in some cases would weaken the report a Pro on the clock could file. Pro's simply don't have time to be that involved on the difficult ones and has limited time to hunt till they really must move on. Either way an occasional bump up in current condition for any station in the database is very useful and valuable.
Rob
-
Bicknell,
Yes there is a rhyme and reason, and though i have written about this in the past, I don't recall which post I did it in, though I will attempt to locate it.
This Is a Bench Mark. Now Before you sat Doh! Let me elaborate a bit. Here at geocaching we tend to walk on the technical terminology of Surveying a little. A Bench Mark most specifically is a location of measured elevation. We also refer to it in a few other ways such as vertical control, Level lines, and lines of leveling.
Back in the day, before GPS, elevations were determined by a method called differential leveling. This method still is used.An optical device such as a level, transit or theodolite could be used to measure a number on a leveling rod, which is a form of story pole with either Metric or Feet and tenths of a foot marked on it, and 2 locations would be compared against one another to clarify the elevation as either a sum or a difference from place to place. It is found that when this process is performed the results are path dependent. What I mean by this is that if you and I were to go leveling from a similar location to another location where we would both meet and yet we both used a different path to arrive at the same place, we would have different results. The relative accuracy of your path to mine would be very close but not the same, and yet in geodesy it needs to be not only the same, but also repeatable.
Bench Marks when set are named to account for the Path and the order in the Path. It is called a Level Line. This Level Line is 255 which is likely only true within the State you are in, as this number will likely have been and you found stations P and Q, there are likely others in the sequence of alphabet on that line to find as well.
Generally speaking Leveling will use the naming convention of three numbers followed by a letter if set by the NGS or its predecessors CGS USCGS etc, and if monumented during the pre GPS area.
Generally speaking Triangulation Stations and other Horizontal Control will be named using Names of either what is being used, where the station is, or who owns the land it is on, but sometimes it is also named for what can be seen from there or other unconventional schemes.
Not all survey markers are just Horizontal control and so sometime both types of data can be present especially since GPS and so the former naming conventions will not always seem to carry over. For the most part that is the gist of naming NGS monumented stations.
Other agencies used various other schemes and sometimes their stations were included in NGS survey. Those stations are not usually found to follow NGS naming criteria or schemes. Nothing in surveying is meant to be a random chance, though sometimes the odd pattern may appear. The hope is Surveying helps to create order more than chaos, but then that is a story for another time! :-D
Enjoy!
Rob
-
DBC,
It is not so much that C/L monuments are on this site per se, But when the Geodetic Surveyors needed a point someplace, and a city monument was handy, they often used it. When they did, and did very intermittently, they wound up in the NGS Database. I have noticed that they either used it for to turn angles for third order, or they some how decided to piggy back it in as an RM to a nearby mark and then turn angles on it for extra positions.
In any case, that is how they seemed to wind up as Geodetic markers, otherwise, they are not NGS property, and is why we only happen across them from time to time. Most C/L Marks, Likely more than 99% of all of them when taken as a whole, Nationally, are not in this database.
Rob
One Quick Question
in Benchmarking
Posted · Edited by evenfall
Hi Paul,
For the most accurate measurement at the, well, moderate cost, a Nylon Clad Steel Tape which measures feet in tenths would probably last the longest remain the most accurate and take the wear and tear of being tensioned taughtly while measuring under repeated use.
The other instruments you have, too have their place. I use the wheel type units quite often when figuring earthwork volumes for bank yard quantities, cut to fill ratios and basic area calculations where I really only need a ball park idea. The larger the wheel the higher the 'relative' accuracy. These work great if you need to make rather lengthy linear measurements, where a close enough measurement will get you where you want to go. Most people probably realize this, but a hint for keeping tapes in better condition is to wipe them off as you roll them up or after use. Sand, Grit and Moisture can soil, abrade and otherwise damage any tape measure.
Rob