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geojibby

Benchmark Question

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Hi friends - I'm trying to find Geological/Geodetic Survey of Canada benchmark information to check the "accuracy" of some GPS receivers. I went to the nrcan website, signed up for my free account, and nothing is straightforward or easy (as with most government websites). How can I search for a benchmark number??????? Any help appreciated. :)

Edited by geojibby

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Once you signed in look for the CSRS Database Request section and select the Go button. The next screen gives you a number of options for searching including Station Unique Number Search.

 

Note that only federal benchmarks are listed in this database and you may have to look elsewhere for provincial benchmarks. If you can describe the benchmark others here might be able to help you more.

Edited by PDOP's

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Hi geojibby,

 

Geocaching .com does not have a category for Canadian Benchmarks unfortunately.

 

The Calgary Geocachers have a list of many of Alberta Brass Caps/Benchmarks/surveymarkers. www.calgarycachers.ca

 

mwellman

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...you could always go to the cache page of a cache near you... and click on "All nearest WAYMARKS"... and then perhaps one of the nearby Waymarks will be a Benchmark with it's designation and location.

 

e.g. You recently found "Moray Monster"

 

Clicking on "Nearest Waymarks" displays a LOT of Canadian benchmarks.

 

500m from that cache is Benchmark "74M611 - Winnipeg MB".

 

To research a Canadian benchmark, go to the NRCan site and navigate to :

 

Natural Resources Canada > Earth Sciences Sector > Priorities > Canadian Spatial Reference System

 

You can use the free user account to then do "Online Database" and then do a "CSRS Database Request" .

 

You are looking for the "Station Unique Number Search" ID.

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And for that benchmark...

 

STN NO NAME EAG Latitude Longitude HDA O I M YRA ELEVATION VDA O Q M DATUM YRA SMC COND NTS

74M611 74-M-611 100 49 52 30 97 15 58 S S 237.446 100 1 P 1 CGVD28 1974 1 1 062H14

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Thanks for the help on this one. I tried the Waymarking tip for caches that are local to my area and I did not yield any results. I have found 2 benchmarks/brass caps near my area and they both had "2450" stamped on them, as well as "geodetic survey of canada" - I uploaded this pic as part of a geocache log.

814b64a1-3325-4eb3-bb40-949013cf9043.jpg

 

Edit:

I didn't get anywhere using CSRS database. Very puzzled about that. OK, I was able to do search based on location and that provided me with a bunch of results. My goal is to test the "accuracy" of some GPSrs so, which of the results is the best to find for averaging coordinates? Are all these stations and what not surveyed with the same accuracy? :laughing:

Edited by geojibby

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...OK... so if I go by your first cache placed (assuming that's "Close to home") and I look at Geodetic markers in your immediate area... I get this (and a whole bunch more)

 

24502 DUNBAR 100 49 2 24.8 102 40 9.4 Y 610.2 100 U X 2 CGVD28 1976 1 1 062E02

24503 SPY 100 49 1 26.5265 102 17 30.5489 100 Y A R 2001 585.9 100 Y X 6 CGVD28 1982 1 1 062E01

24505 MARTIN 100 49 2 19.4 102 4 51.2 Y 1 1 062E01

24506 GOERTZ 100 49 3 54.5 101 50 1.4 Y 1 1 062F04

 

The image you uploaded is of a triangulation station not a typical "marker". Its position has been determined by measuring distances and angles from other stations.

 

I don't see record of them (unless they are the ones listed above -- but I don't believe they are).

 

If you go onto the same webpage and do a "Radius Search" around your home co-ords you should hit a "Benchmark" that is listed and has record co-ords to play with.

 

I'm looking more.... can you post (or message me) rough co-ords to play with if my "first cache you placed" guess is way off :laughing:

 

 

I'm enjoying this... the NRCAN site is better than I recall!

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Ok, I redid the radial search and I got one station within 10km of home. The station number is: 11S56C and generated this long report:

 

SITE IDENTIFICATION

 

Unique Number : 11S56C

Name : 56C

Established by : Geodetic Survey Division

Province : SK

Prov. Identifier : None

NTS Map No : 062E01

 

STATION COORDINATES

 

Method : Scaled

Latitude : N49° 14' 06"

Longitude : W102° 12' 54"

Agency : Geodetic Survey Division - NRCan

UTM : Zone = 13 Scale Factor = 1.0001 N = 5457313 m E = 702730 m

 

VERTICAL DATA

 

Vertical Datum : CGVD28

Elevation : 556.993 m

Order : First Order

Method : Differential

Adjustment Line : VA13

Published Year : 1911

 

STATION MARKER INFORMATION AND LOCATION

 

Marker Type : Permanent Agency Marker

Inspected in : 1911

Status : Good

Inspection Comments : None

 

OXBOW

 

C.P.R., CONCRETE ARCH CULVERT , 188.2 KM FROM KEMNAY, 3.2 KM NORTHWEST OF STATION, BETWEEN THIRD AND FOURTH POLES EAST OF MILE POST 117, TABLET IN WEST END OF NORTH FACE, 21 CM BELOW TOP.

 

HISTORICAL COORDINATES NOTE: Coordinates listed below are no longer maintained by GSD and should be verified with your provincial agency before use.

 

None

 

PROJECTS IDENTIFIERS:

49102 VA13

 

So I just punch in these coordinates, go there and there will be something there matching this description? :laughing:

 

...OK... so if I go by your first cache placed (assuming that's "Close to home") and I look at Geodetic markers in your immediate area... I get this (and a whole bunch more)

 

24502 DUNBAR 100 49 2 24.8 102 40 9.4 Y 610.2 100 U X 2 CGVD28 1976 1 1 062E02

24503 SPY 100 49 1 26.5265 102 17 30.5489 100 Y A R 2001 585.9 100 Y X 6 CGVD28 1982 1 1 062E01

24505 MARTIN 100 49 2 19.4 102 4 51.2 Y 1 1 062E01

24506 GOERTZ 100 49 3 54.5 101 50 1.4 Y 1 1 062F04

 

The image you uploaded is of a triangulation station not a typical "marker". Its position has been determined by measuring distances and angles from other stations.

 

I don't see record of them (unless they are the ones listed above -- but I don't believe they are).

 

If you go onto the same webpage and do a "Radius Search" around your home co-ords you should hit a "Benchmark" that is listed and has record co-ords to play with.

 

I'm looking more.... can you post (or message me) rough co-ords to play with if my "first cache you placed" guess is way off :)

 

 

I'm enjoying this... the NRCAN site is better than I recall!

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You probably want to choose another one:

Method : Scaled

A lot of these are scaled off a map and so will be 10's of metres off. If you're wondering why a benchmark would be so inaccurate, many of these are used for gravity measurements only and have very accurate elelvations.

 

Inspected in : 1911

 

HISTORICAL COORDINATES NOTE: Coordinates listed below are no longer maintained by GSD and should be verified with your provincial agency before use.

If true that's quite old.

 

Anybody here know if Saskatchewan has an online database open to the public?

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You should get a free account at NRCAN see

 

http://www.geod.nrcan.gc.ca/online_data_e.php

 

 

this will then let you search for more databases,, the Canadian High precision Network has several control stations of very high order in several locations in each province These are set up to allow GPS users access to precise survey point locations to calibrate their receivers,,

 

As mentioned above the survey control point may be listed as a First Order point but it's coordinates may not be updated in the data base,,

 

do the research or if you want I can find a point close to you if you want,, send info to me,,

Edited by stagunner

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So is differential preferred for benchmarking (that is, averaging a waypoint with a GPSr)? :)

 

 

What's the difference in scaled or differential?

Scaled means measured off a paper map. A lot of these are for the Canadian Gravity Standardization Net (CGSN)

 

Differential is an accurate type of GPS surveying. See How to do a GPS survey to centimetre accuracy.

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So is differential preferred for benchmarking (that is, averaging a waypoint with a GPSr)? :)

Definitely.

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