Jump to content
Sign in to follow this  
Followers 1
ArtMan

Pid Is Not Point Id

Recommended Posts

PID in several places in the geocaching.com universe is alleged to stand for "point ID." In fact, the NGS website indicates it stands for "Permanent Identifier."

 

I don't believe this has come up before in this forum; at least a search didn't produce a previous thread.

 

Am I the only one who has noticed this?

 

-ArtMan-

Share this post


Link to post

I am curious about the first 2 letters of the PIDs that we've been living with here. What are they from? I'm hoping someone from the NGS will answer this trivia question.

 

I recall the ones that start with A have a special meaning, and I forget what it is. Is there a list somewhere of the special ones and their meanings?

 

What about all the rest? Here in the DC, MD, VA area, we have a lot of HV and JV. (with a few starting with A thrown in). Are these the initials of someone in the NGS who assigned the PIDs? Was it done by project? The number part doesn't correlate very well with the marker's age. Is there any special significance to PIDs HV0001 or JV0001, HW0001, etc.?

 

 

This mesag has been edited for bad speling; bad punctuation, some stuff from an the editing process, logic error's, an magnanimous ignorance of word definitions and basis concepts.

Share this post


Link to post
What about all the rest?  Here in the DC, MD, VA area, we have a lot of HV and JV. (with a few starting with A thrown in).  Are these the initials of someone in the NGS who assigned the PIDs?  Was it done by project?  The number part doesn't correlate very well with the marker's age.  Is there any special significance to PIDs HV0001 or JV0001, HW0001, etc.?

In my area, most of the PID's begin with either RD or SC. There seems to be no correlation to monument date from 1987 to earlier. The ones monumented in 1987 (rod types), and they may have either a RD or SC prefix. The oldest ones (1874) seem to have RD prefixes. The intersection points around here seem to have RD prefixes. There are two marks nearby that were monumented in 1991 and 1997, and these have an AA and AH prefix respectively. The prefix QE seems to be popular in my state, although theres no marks near to me with this prefix.

Share this post


Link to post
I am curious about the first 2 letters of the PIDs that we've been living with here. ...

 

What about all the rest? Here in the DC, MD, VA area, we have a lot of HV and JV. (with a few starting with A thrown in). Are these the initials of someone in the NGS who assigned the PIDs?

My impression is that, except for AA and possibly other special series, they were assigned as added to the NGS database, which sometimes appears to have been done by project (L113, L114, L115 and L116 might have sequential PIDs, but then L117 might not), and sometimes not.

 

Are the letters I (eye) and O (oh) used, or are they skipped to avoid confusion with numbers 1 (one) and 0 (zero)?

 

-ArtMan-

Share this post


Link to post
Are the letters I (eye) and O (oh) used, or are they skipped to avoid confusion with numbers 1 (one) and 0 (zero)?

Most of the markers near me start with OH (oh H).

 

OH0081 is an example with an Oh and Zeros.

 

I don't know about just O's (ohs) in the prefix though,

Share this post


Link to post

Surveying Theory and Practice.

 

Art. 9-2. BENCH MARKS.A bench mark(B.M.) is a definate point on an object,the elevation and location of which are known.It may be permanent(P.B.M.) or temporary (T.B.M.).

Bench marks serve as points of reference for levels in a given locality.

Their elevations are established by differential leveling,except that the elevation of the initial bench mark of a local project may be assumed.

 

Throughout the U.S. are permanent bench marks established by the U.S.G.S. and of the U.S.C&G.S..

Similarly,bench marks have been established by various other Federal,State, and municipal agencies and by such private intrests as Rail Roads water companies,so that the surveyor has not far to go before he can find some point of known elevation.

 

I can not find PID any where.

Share this post


Link to post
I recall the ones that start with A have a special meaning, and I forget what it is.  Is there a list somewhere of the special ones and their meanings?

I don't think so. South Texas in Cameron County all PIDs start with AB. Furthermore, south Florida has AA0314 and others which are not special. As far as I can tell, designations start with counties in the south and work east to west northward.

Edited by Colorado Papa

Share this post


Link to post

I have found AA prefix's up here in Michigan also. I would bet its just some computer generated ID.

Edited by elcamino

Share this post


Link to post
I have found AA prefix's up here in Michigan also.  I would bet its just some computer generated ID.

I just looked at your User Stats page #7 and see my theory is blown out the window. Why don't we just ask DaveD for an explanation? :(

 

Edited to add page #7 since could not access that page directly with http://.

Edited by Colorado Papa

Share this post


Link to post
Are the letters I (eye) and O (oh) used, or are they skipped to avoid confusion with numbers 1 (one) and 0 (zero)?

 

Apparently I and O are used in the two-letter PID prefixes (I've seen a number of AI marks myself), but they do not appear to be used in the designations of marks in a series.

 

For example, check out some of the complete series of marks I'm working on currently:

 

Level line recoveries

 

You'll notice that all the letters but I and O are represented in the series (I didn't list A 281, V 281, or Y 234, which are all non-publishable marks). I've noticed this in other series as well.

 

This may be a convention rather than a "rule" but I can see the practical value. I always assumed it had to do with the possible confusion of "I" and "1", and "O" and "0".

 

~Zhanna

Share this post


Link to post
I am curious about the first 2 letters of the PIDs that we've been living with here.  What are they from?  I'm hoping someone from the NGS will answer this trivia question.

 

As you know I'm not from NGS, but I have made some observations that lead me to think that the two-letter prefix is related to the latitude and longitude of the mark. I've checked the datasheets for many marks in my general hunting area and find that the prefixes fall into a definite pattern: "LY" marks fall between N 41° and N 42°, and W 74° and W 76°. Immediately outside those boundaries, the letters change.

 

I have not found any exceptions other than the "A" marks (AA, AI, etc.) that have been mentioned in this thread, and a few very new marks that have different prefixes which don't seem to fall into any pattern. I don't know if this pattern holds true everywhere, but to illustrate what I found I've compiled a chart of the general trend I see in my area and surrounding areas:

 

pid_prefix.gif

 

Has anyone else noticed something similar?

 

~Zhanna

Share this post


Link to post

Interesting. It does seem that the beginning of the alphabet is in the FL corner of the country, and the end of the alphabet is in the WA corner of the country.

Share this post


Link to post
As you know I'm not from NGS, but I have made some observations that lead me to think that the two-letter prefix is related to the latitude and longitude of the mark.

pid_prefix.gif

:) Good observation. Add JG prefix between N38 and N39 by W098 and W099,

FB prefix between N35 and N36 by W82 and W83.

Can give you a lot more prefixes if desired.

Share this post


Link to post

JB @ N38, W089; JC @ N38,W090 & N38, 091; JD @ N38, W092; KC @ N39,W090 & N39,W091; would seem to connect one of Colorado Papa's (JG) with Zhanna's array. VERY CLEVER Zhanna and the rest of you!!

Share this post


Link to post
I recall the ones that start with A have a special meaning, and I forget what it is.  Is there a list somewhere of the special ones and their meanings?

I don't think so. South Texas in Cameron County all PIDs start with AB.

But not all ABs are in Cameron County, Texas. Just found this listing in my home state!

We maybe beating a dead horse. We can only surmise that it started as a logical way to assign PIDs, but many are not according to logic. Oh well, it has been an interesting topic. Now should be start trying to figure out how the numbering system was assigned?

 

DaveD, WHERE ARE YOU???

Share this post


Link to post

We maybe beating a dead horse.  We can only surmise that it started as a logical way to assign PIDs, but many are not according to logic.  Oh well, it has been an interesting topic. 

All's not lost. With the exception of the Cameron County, Texas AB marks, I'm pretty sure that all or the vast majority of the A marks I've seen have been relatively new; that is, monumented post-1990 or so. Could that have something to do with it? Maybe a new numbering system began around that time?

 

There must be some logic to this!

 

~Zhanna

Share this post


Link to post

Michigan

 

41N to 47N

82W to 90W

 

prefixs in use;

Scattered, all from 1994 on.

AA,AB,AC,

 

Common

MC,MD,ME,NE,NF,NG,OJ,OK,PK,PL,PM,RH,RJ,RK,QJ,QK,QL,QM,RL, SG,TY,

too name a few

Edited by elcamino

Share this post


Link to post

The AA series near St. Louis, MO fits Zhanna's theory in that they are 1989 & later. There also a few AI, AJ and AC around here that are post 1990. The 2000 MO center of population disk (NGS listing only) is DE6442 though....

 

I suspect that the folks who post here could nearly fill out the U.S. map with the pre-1990 designations. Starting with Zhana's map & extending it. The letter series from elcamino appear that they would fit in nicely.... B)

Share this post


Link to post

I'd love to get a 700,000 line extract list from Jeremy in 3 columns, 2-letter-prefix, lat, lon.

 

I bet there's only about 70 different 2-letter prefixes in the whole list. 70 plots on the U.S. map would be highly amusing.

 

I agree with Zhanna's idea that the assigning of PIDs changed around 1990 from a regional basis to a national basis.

Share this post


Link to post

You can get a list of one liners from NGS, you just have to get it state-by-state from the misc files section. I happen to have mine laying around waiting for such an analysis opportunity to come up. It includes both published and nonpublished benchmarks, totaling 852,997. Nonpublished benchmarks are mostly listed as destroyed but they certainly fit the analysis here. Here is some interesting facts that I’ve been able to pull out so far.

 

There are 479 prefixes used out of a possible 676 (26 times 26). I did a summary based on prefix, degree of latitude, degree of longitude. 251 prefixes lay within entirely within a single latitude/longitude pair or within two separate latitude/longitude pairs. For example, prefix BC has 2,325 entries that lay entirely within 30N, 81W. And prefix GV has 5,628 entries that lay within two lat/long pairs, 37N, 76W and 37N, 77W. Another 143 lay in three lat/long pairs and 48 more in four lat/long pairs. That makes 442 prefixes out of 479 that are confined to a fairly small area. AA is the most spread out, covering 481 lat/long pairs. AB thru AJ are also spread out, with UW (222 lat/long pairs) and DE (199 lat/long pairs) being the most spread out non-A prefixes.

Share this post


Link to post
Rogbarn -

 

Very cool analysis! 479 is obviously surprising to me.

 

Can you make us a 479-color plot map of the U.S.? (Suitable for framing :o)

uh, sure BDT, anything for you... :unsure: the only cost is, uh, check out info about my walk

 

Some more detail:

 

Of the 251 prefixes within one or two lat/long pairs, 12 are entirely within one lat/long pair. Of the 239 that are within two pairs, 4 are within adjacent latitudes, the other 235 are within adjacent longitudes.

 

Now, looking at it from latitude and longitude point of view:

There are 1,408 lat/long pairs (e.g. 39N, 90W is one lat/long pair). 447 are for Alaska and Hawaii, I’m going to throw those out just to try to make it a bit easier. That leaves 961 pairs, from 24N to 49N and 66W to 124W. There are 111 lat/long pairs that have only one prefix. 126 have two prefixes, 130 have 3 prefixes, 149 have 4 prefixes, 111 have 5 prefixes. That makes 627 lat/long pairs with 5 or fewer prefixes within each pair.

 

There are 15 prefixes within 26N, 80W, the most prefixes for any lat/long pair.

 

There is just one benchmark in 39N, 124N, it is PID UT0743. I looked it up, the reason there is only one in that lat/long is that the corner of the box just hits the northern California coastline, leaving very little land to place a benchmark within that latitude and longitude. Actually, the benchmark is a bit off shore, and old, so it would be a neat one to log.

Share this post


Link to post

Ummm, I was going to stop, but one last look lead to another which lead to another which, well, I just figured I had to post a little bit more:

 

There are actually 18 lat/long boxes with just one benchmark in them; the one that I mentioned in my previous post, plus 9 in Hawaii and 8 in Alaska. Of the 9 in Hawaii, 8 are in the Northwestern Hawaiian Islands, a series of small volcanic islands that is a federally restricted area. The last one in Hawaii is listed as destroyed. Of the 8 in Alaska, 4 are listed as destroyed. So, only 4 have the potential of being found. They are: UV3124, UV7971, UW4603, and TT5847. The last one is not in GC, I think because it is past 180 deg longitude. The NGS lists benchmarks beyond 180 with a longitude greater than 180, for example, this one is listed with a longitude of “184 05 22.21040(W) ADJUSTED “.

 

The lat/long with the most benchmarks is 34N, 118W with 6,725 – earthquake country.

Share this post


Link to post

Most of you have it made in the shade, when we are trying to find benchmarks and Geocaches on the same day around town it hard watching the screen on the gps , our PIN # are GC in Nashville ……………LOL ………….. JOE

Share this post


Link to post
The lat/long with the most benchmarks is 34N, 118W with 6,725 ? earthquake country.

Ahh! Home sweet home! I live about 15 miles from that point.

 

Unfortunately, I think that 6,725 number is a lot lower. Here in So. Cal. we pave over just about anything developers can get their mitts on.

 

I know there is a large number of markers in my area and around my work that have gone missing with notes such as 'A housing development was built in the area where the location plots to and the ground has been graded to a depth of 7 feet' or similar notes.

 

That being said, there are still a TON of them everywhere I doubt I will ever be able to look for all of them... I am blessed to live in Benchmark Country.

Share this post


Link to post

Just an FYI for anyone interested:

 

I am up in Maine around the 44-45 degree N and 070 degree W area. All our prefixes are OC (Oscar Charlie) and PF.

 

I did some hunting in North-western NJ recently on a business trip.......they were all KV prefixes.

Share this post


Link to post

OK, for those of you who like order in the universe, you can rest easy. It appears that PID prefixes were assigned in blocks of 1 degree of latitude by 2 degrees of longitude starting with AA in block 24N, 80/81W in south Florida. The blocks go east to west until the U.S. border ends then goes up one degree of latitude. There are a few exceptions, mostly around the coastline. I suspect the spread out nature of PID prefixes starting with A is due to additional PIDs being needed in some areas and being assigned whatever was first available. I made a map of the most frequent PID prefix by latitude and longitude. It is available here

 

edit: typo

Edited by rogbarn

Share this post


Link to post

Excellent PID map, rogbarn !!!!!!!

TY

Share this post


Link to post

Very nice, rogbarn !

 

Yes I am one of those that appreciates order in the universe on some occasions (although randomness can be quite beautiful in other situations).

 

I had some difficulty in getting a printout in Internet Explorer, but a paste Excel worked after some fiddling with line heights and making the font a lot bigger.

 

Now, if only the Benchmark Gallery at least had the automatic PID on the pictures again.......

Share this post


Link to post

Excellent work, Roger. In fact your map is very similar to the image I had I my mind of how I expected these prefixes to be ordered. I haven't had enough time this week to work on it more extensively, so I'm glad you were able.

 

OK, for those of you who like order in the universe

Yes, there are still a few of us!

 

~Zhanna

Share this post


Link to post
I made a map of the most frequent PID prefix by latitude and longitude. It is available here

Wow, that's pretty cool- it even looks like the United States!

Uh... how long did that take you? What database program are you using to analyze the data? (Just sheer curiosity!)

Share this post


Link to post
OK, for those of you who like order in the universe, you can rest easy. 
Thanks, Rog. Great job! Saves me the trouble of finishing the same type of thing.
What database program are you using to analyze the data?
I don't know about Roger, but I was doing a search of Nxx 30.0, Wyyy 30.0 to get the middle points.

Footnote: Wonder why prefix BF was skipped?

Share this post


Link to post
I made a map of the most frequent PID prefix by latitude and longitude.  It is available here

Wow, that's pretty cool- it even looks like the United States!

Uh... how long did that take you? What database program are you using to analyze the data? (Just sheer curiosity!)

I started working on it yesterday. I have previously downloaded all of the misc files from the NGS for all 50 states. The misc files consist of 3 files for each state, one of all published control points, one of all non-published control points and one of a list of all counties in that state. The lists of control points consist of PID, lat, long and for the published ones, which county file they appear in. I have these files concatenated together (so I can't tell which state the non-published ones are in, or, at least, were in). It is stored on a VAX computer. I wrote a quick little program to summerize by PID prefix, degrees of latitude and degrees of longitude, resulting in a table of those fields with a count of number of entries in each group. I downloaded that to my PC and sucked it up into Excel where I was able to play around with the data to get it to tell me something interesting. The map is just an Excel spreadsheet saved as a html file.

Share this post


Link to post

How about this one??

It took me a while to copy what rogbarn did into my mapping program... now that it's done, you can make yourself a nice wall mountable map :ph34r:

 

Benchmark Image

 

(sorry, I only have a geocities account to post this to... it has a pop-up ad)

Edited by sbolish

Share this post


Link to post
It took me a while to copy what rogbarn did into my mapping program... now that it's done, you can make yourself a nice wall mountable map :)

 

Benchmark Image

 

(sorry, I only have a geocities account to post this to... it has a pop-up ad)

:ph34r: Oops, got an error message and can't check back in an hour:

 

Sorry, this site is temporarily unavailable! 

The web site you are trying to access has exceeded its allocated data transfer. Visit our help area for more information.

Access to this site will be restored within an hour. Please try again later.

http://www.geocities.com/sbolish/benchmark.html

Share this post


Link to post

I was hoping some one else would perk in there on the rogbarn map.

 

I have been looking for the detailed info on the 1* X 2* Map projections,but have been unable to find exactly what I want.

 

It will fit right in on rogs letter map.

Share this post


Link to post
It took me a while to copy what rogbarn did into my mapping program...

Nice map. Thanks for the effort.

If I may point out a slight error, the letters AB are transposed in the Texas Big Bend area. Should be BA (Approx N29, W103). Rog had his correct.

Share this post


Link to post
How about this one??

Wow, this is an awesome map. Thanks for the added on value to my original.

Share this post


Link to post

Sorry for the late chime in on this one, I'm just learning the value of the forums.

 

The two-digit lettering system looks just like (but doesn't match) the Military Grid Reference System and World Grid Reference used on ONC, TPC and other charts. In the MGRS, the two letters identify a 100,000m square.

 

Not the same, but at some point somebody may have modeled after it to create their reference system.

Share this post


Link to post

Can't count that high.

 

On the Great Map combination.............you could use any prefered reference system you wanted such as Degrees,in proper order,letters, or numbers.

 

I still think the 1 Degree X 2 Degree would look neat.

Share this post


Link to post
How many different 2-letter PID codes are in your "Found it" list?

 

21 here.

right behind you with 20

Share this post


Link to post
How about this one??

Wow, this is an awesome map. Thanks for the added on value to my original.

If you'd like to host it on your website, please feel free... geocities is not very reliable these days.

 

Also, I can offer up a .wmf (vector) version of the map that can be printed into a poster size :huh: for anyone who'd like to hang one on their wall. The file will likely be a couple MB though. I don't think I have enough room on geocities to post it. Any takers??

Share this post


Link to post
I don't think I have enough room on geocities to post it.  Any takers??

 

I have hundreds of MB of web space and a website for all things survey mark related, so I'd be happy to host the maps for you.

 

~Zhanna

Edited by Zhanna

Share this post


Link to post
I don't think I have enough room on geocities to post it.  Any takers??

 

I have hundreds of MB of web space and a website for all things survey mark related, so I'd be happy to host the maps for you.

 

~Zhanna

Zhanna graciously took over my list of airway beacons because I get a limited amount of webspace. It would be nice to add it to her collection of benchmark related pages.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
Followers 1

×