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birdseye8 post(s)
#10-Aug-16 20:27

Does Manifold support NAD83 CSRS? ("NAD83 NSRS" in U.S.)

Some background: http://aep.alberta.ca/lands-forests/director-of-surveys/documents/FactSheet06-ImpactNAD83Adoption-Feb2010.pdf

Is there any way to convert from NAD83 CSRS (NSRS) to NAD83 "original" using Manifold? Our main data provider has traditionally provided us with shapefiles in the original NAD83 projection but has now adopted the NAD83 CSRS federal standard.

Thank you.

tjhb
10,094 post(s)
#10-Aug-16 20:37

From your background:

To comply with the International Association of Geodesy (IAG) recommendations, Canada and the US have adopted a common similarity transformation between ITRF96 and NAD83 (Original), which effectively provides a unified definition of NAD83 throughout both countries.

As I read that, we may be able to implement the official similarity transform to create a custom ellipsoid in Manifold XML.

Some checking to do on that.

tjhb
10,094 post(s)
#10-Aug-16 22:51

Quick update: for now I'm confused. (I get confused with this sort of thing.) Hopefully temporary.

tjhb
10,094 post(s)
#10-Aug-16 23:34

Here's my stab at a summary. Please correct me if you can (there are some trained surveyors here).

Originally, NAD83 was directly related to a fixed version of the GRS80 ellipsoid.

GRS80 has since been adjusted to depend on the ITRF, and is now dynamic. NAD83 (CSRS and NSRS) are related to this new dynamic GRS80 ellipsoid. (This also affects WGS84.)

Normally, for GIS purposes, it isn't necessary to worry about these differences. For synchronic data (positions measured or made correct at the same time), it is correct just to use GRS80 as the ellipsoid, since this is same reference frame at the same time.

However, if there is an explicit need to convert between data measured or made accurate under the old, fixed versions of NAD83/GRS80, and data relative to the new dynamic versions (and if differences in the order of several centimetres are significant for our purpose), then we need to use a transformation.

The official 7-parameter Helmert transformation model for NAD83 (for both fixed and arbitrary timeframes) is given in Realization and Unification of NAD83 in Canada and the U.S. via the ITRF, available from the US NOAA here.

So yes, I think we can do this. Because I'm not on very firm ground I want to sit on this for a moment--and give others a chance to chime in with observations and corrections--before writing up some XML for the transformation(s).

Then we would need to test, with known good data measured in NAD83 (original) and NAD83 (CSRS or NSRS) measured at a known time.

birdseye8 post(s)
#11-Aug-16 15:50

Thanks for putting your mind to work on this. This is way beyond my level of knowledge!

Dimitri


7,413 post(s)
#11-Aug-16 19:10

There is a lot of detail here to consider. For starters there is not just one CSRS or just one NSRS. This is a case where EPSG codes help, for their precision. Coordinate bases (datums) each have their own EPSG code so using EPSG can cut through the variations in text names that may be used.

If you punch in CSRS to filter all the EPSG codes you get a lot of references with six or more being bases.

Some of these have had names changed over time as highlight by the ! icon and noted in the EPSG database comments.

It's the same with NSRS names, which in their text names (not the EPSG codes of course) seem to be named by epoch as in NSRS2007.

Note the transformation used (see bottom panel of the Coordinate System dialog) is 10-parameter Molodensky-Badekas which is a generalization / upgrade of the 7-parameter Helmert transforms mentioned in the NOAA paper.

I'ts late here and I haven't thought this through on all angles so I may be wrong, but I'd say if you know the EPSG code or can otherwise nail down precisely which CSRS is being used you're good to go. If the provider has recently adopted CSRS they should know the EPSG code for it.

Attachments:
csrs.png
csrs2.png
nsrs.png

tjhb
10,094 post(s)
#11-Aug-16 22:36

Thanks Dimitri!

I had been wondering whether it would be permissible, now, to use the resources in Radian Studio to answer birdseye's question here (which is about Manifold 8).

I hadn't tried that yet but my idea would have been to use Radian's massive database of coordinate systems as an authoritative reference, then reuse its transformation parameters to create a custom coordinate system (at least a datum, with possibly one or more projections to reference it) in Manifold 8 XML.

Well, you have answered that and gone further! However, in the way of things, there's a chance that this was inadvertent, i.e. if you thought this was a Radian question rather than a Manifold 8 question (easy to do as we both know).

So I'll wait to see whether your post (and this one) stick around before posting adapted and borrowed XML.

@birdseye:

As Dimitri suggests, and for his reasons, it would be ideal if you could ask your supplier for the exact EPSG code(s) they use to publish the data you receive from them, for each projection you receive it in (and if unprojected as well, then an EPSG code for that too).

And for testing, can you get hold of some simple sample data, at least one drawing or shapefile using original NAD83, and one using the new coordinate system(s), which you expect to line up exactly. For example some known survey points or property bounadries. Just a few common features is enough, but the more widely spaced over your province or AOI, the better.

dale

630 post(s)
#12-Aug-16 08:49

And thanks Tim,

I'd started to hunt through the Manifold 8 manual to find the never before seen Coordinate System dialog box. (which I note has features that I'd vote for!)

It's obviously not there.

Dimitri


7,413 post(s)
#12-Aug-16 08:52

Well, you have answered that and gone further! However, in the way of things, there's a chance that this was inadvertent, i.e. if you thought this was a Radian question rather than a Manifold 8 question (easy to do as we both know).

Oops. That's what I get for visiting the forum from home late in the evening. :-) Yes, I thought it was a Radian thread. But that's OK as the solution in any event is to be found in the public EPSG database, whether you look that up yourself with EPSG or look it up in a package that supports EPSG.

Yes, please if there is anything in Radian Studio EPSG that you can recycle into an 8 customization please do so. Whatever helps is good. The EPSG stuff is open to the public from EPSG anyway (thank you, EPSG!).

I am not, by the way, convinced that EPSG's database as published in Radian is perfect. For example, EPSG:4140 says it is replaced by 4617 and then 4617 in turn says it is replaced by 4461. Several other EPSG entries say they are replaced by 4461 as well. But there is no EPSG:4461 in the EPSG database within Radian.

I've reported that as a possible bug, either we missed something when adding a few thousand entries into the product or the EPSG database is not perfectly self-consistent. Or both. :-)

But for all that I have to say having thousands and thousands of precise EPSG codes that call up a specific coordinate system - exactly - on demand is really wonderful.

Gustavo Palminha

1,010 post(s)
#12-Aug-16 11:57

Using http://spatialreference.org/ and searching for "NAD83(CSRS)" retuned many EPSG codes.

From your original post, and after cross checking the EPSG codes and names, some show up mentioning "alberta" which I've copied all of them to attached spatialreference_nad83.txt file.

From http://www.georeference.org/forum/t93039.7 I've added a map file with a list of EPSG codes supported by default by manifold 8.

After checking which EPSG codes already exist with this spatialreference_nad83.txt file some appear to be supported and you can find them inside the "spatialreference_nad83_manifold_supported.txt" file.

If any of these EPSG are suitable for you then you are in luck. If not, then you need to create a custom projection xml file and test it.

Good luck.

Attachments:
spatialreference_nad83.txt
spatialreference_nad83_manifold_supported.txt


Stay connected:

Linkedin >> http://www.linkedin.com/in/gustavopalminha

Twitter >> http://twitter.com/gustavopalminha

Other >> http://www.spatialmentor.com

birdseye8 post(s)
#24-Aug-16 21:43

tjhb: The EPSG code is 2958 for the new NAD83 CSRS data. I'm working on getting some sample data that I can share. Should be able to post soon. Thanks to all for your interest and help!

tjhb
10,094 post(s)
#24-Aug-16 22:53

Great, 2958 wouldn't have been my guess, so knowing the right code saves time.

Now to use the deep resources of Radian Studio beta to make correct XML for Manifold 8. Back soon.

tjhb
10,094 post(s)
#25-Aug-16 05:12

OK, getting somewhere.

Radian Studio and EPSG itself have both been very helpful.

Two points.

(1) We can easily define the projection "NAD83(CSRS) / UTM zone 17N (EPSG:2958)" for use in Manifold 8.

(2) I am becoming confident that the issue of conversion is less complicated than I had thought. I think accurate definition will take care of it. Testing will tell.

tjhb
10,094 post(s)
#26-Aug-16 02:19

I have this done now--in three very slightly different versions. All three seem fine on fake data. Once we have sample real data, we can see which is more accurate in practice. (There's room to tighten them up even more if necessary for a special purpose.)

Ideally it would be good to have survey-quality data released under one of the original NAD83-based projections, and survey-quality data released under one of the new NAD83 (CSRS)-based projections, with some matching locations between the two. That might not be possible. Anything useful to you would be good.

tjhb
10,094 post(s)
#26-Aug-16 03:27

There are also updated NTv2 grids for some provinces,* for converting directly between NAD83 (original) and NAD (CSRS).

It might be good to add these in too.

*Specifically Alberta, Québec and Saskatchewan. What province(s) do you work in?

tjhb
10,094 post(s)
#26-Aug-16 08:23

I think I might have over-complicated things here--though in my defence I think that has something to do with the Alberta fact sheet birdseye pointed at (rightly so, I'm not blaming birdseye) at the top of the thread. It makes no serious effort to explain the importance of the different datums to ordinary GIS mortals like us--and I suspect members of the audience with enough surveying experience to understand it fully would not need the fact sheet at all.

A lot of the other available documentation is similar, preaching to the choir with little regard for ignorant sinners, and of course that is not a novel approach. But wading through it is a great learning experience, I've personally got a lot out of it. (For example I'm no longer scared of the EPSG database, even the dark bits I never even knew were there. That's really useful.)

But there's no substitute for actually knowing what you're doing, and in some domains, surveying and dentistry being two, serious training is the only way to get there.

I now have a stack of four or five different translations of NAD83 (CSRS) to WGS84, for different ITRF epochs, with varying accuracies and different levels (and areas) of official support.

It's best to put those aside for several reasons. (1) I don't know when the differences between them really matter; (2) I'm sure the answer to 1 depends on the type of data you have and what you need to use it for; (3) birdseye never said he was dealing with high-accuracy survey data; (4) there seems to be a silent consensus that adjusting between different ITRF epochs is best left to surveyors; (5) precision is not the same as accuracy; (6) even Radian Studio (beta) doesn't mess with different ITRF epochs but generally (and in this case) keeps things very GIS-simple; (7) if the simple version doesn't work, we can complicate it later.

So I'll post the simple versions first, maybe only those.

tjhb
10,094 post(s)
#26-Aug-16 09:04

These are very simple, and agree with what Radian Studio does.

The names give an EPSG trail for anyone who needs to know. Search for codes in order 2958-4617-1842.

To install the custom projection, quit Manifold, then copy both files to the Manifold Config folder. For example

C:\Program Files\Manifold System\Config

(You need to confirm administrative permissions.)

To use the projection (with associated datum), relaunch Manifold, then in Assign Projection or Change Projection (depending, in the usual way) choose National Grids > Canada > NAD 83 (CSRS) > UTM Zone 17N EPSG 2958 4617 1842.

The datum North American 1983 (CSRS) 4617 1842 is available for other uses. (But really, it's just GRS 1980. See first line above.)

Sorry for all the palaver. We can complicate this further if actually necessary.

Attachments:
North American 1983 CSRS (EPSG 4617 1842).xml
UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

birdseye8 post(s)
#29-Aug-16 19:54

tjhb, you've done a lot of work! Thank you!!! Here is some sample data taken from our region's SLRN. Does this help with testing? ... Sorry for the Alberta fact sheet earlier... that was something that our data provider had circulated to users as a backgrounder. I'm working strictly within Niagara Region, Ontario.

Attachments:
SampleRoads.map

tjhb
10,094 post(s)
#31-Aug-16 01:36

I thought you were probably in Ontario (or Quebec) because of the projection.

Thanks for the test data, it looks ideal for the purpose.

So I'll see whether it's worth complicating things any further, or whether the simple definition above is as good as it gets. (I admit I hope it's worth complicating things!)

firsttube


1,439 post(s)
#31-Aug-16 14:40

I am in Niagara Region also, and very interested in a possible transformation routine using Manifold. Thanks, tjhb for looking at this!


"The blessing in life is finding the torture you are comfortable with." - Jerry Seinfeld, 6/26/2013

tjhb
10,094 post(s)
#31-Aug-16 23:12

Natural Resources Canada: Adopted NAD83(CSRS) Epochs by province.

Ontario: 2010. Worth doing I think, though a lawyer might have nightmares.

firsttube


1,439 post(s)
#07-Sep-16 20:01

tjhb - I copied these files to the config folder in manifold. When I start manifold now I see the following in the History pane:

Failed to load ellipsoids from: C:\Program Files\Manifold System\Config\UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

Failed to load datums from: C:\Program Files\Manifold System\Config\UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

Failed to load units from: C:\Program Files\Manifold System\Config\UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

Failed to load presets from: C:\Program Files\Manifold System\Config\UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

Failed to load palettes from: C:\Program Files\Manifold System\Config\UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

Failed to load layout templates from: C:\Program Files\Manifold System\Config\UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

Failed to load styles from: C:\Program Files\Manifold System\Config\UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml

Startup complete

Created Project1


"The blessing in life is finding the torture you are comfortable with." - Jerry Seinfeld, 6/26/2013

tjhb
10,094 post(s)
#07-Sep-16 23:55

That sounds very like a Windows "unblock" issue.

See here and (thanks Dimitri, thanks Mike) here.

You must unblock the source at source, then deploy it.

(And yes I am still working on this. More soon.)

firsttube


1,439 post(s)
#08-Sep-16 01:28

Yes, I did unblock the files in the Download folder then copied them to the config folder.


"The blessing in life is finding the torture you are comfortable with." - Jerry Seinfeld, 6/26/2013

tjhb
10,094 post(s)
#08-Sep-16 04:48

Thanks, I'll double check and come back.

birdseye8 post(s)
#19-Oct-16 16:36

I can't seem to get Manifold to recognize the contents of the UTM Zone 17N - NAD 83 CSRS (EPSG 2958 4617 1842).xml file either. When I try to download it, it displays in Chrome with the attached error message. It looks as if the xml coding has been stripped. I'm not sure how to actually download the file -- it appears that I can only view the contents in the browser and then copy and paste into a new file from there. The other file, North American 1983 CSRS (EPSG 4617 1842).xml, displays properly (with xml coding) in the browser window. No issue there.

This page contains the following errors:

error on line 17 at column 1: Extra content at the end of the document

Below is a rendering of the page up to the first error.

UTM Zone 17N EPSG 2958 4617 1842*NAD 83 (CSRS) National Grids*Canada*NAD 83 (CSRS) Transverse Mercator North American 1983 (CSRS) EPSG 4617 1842 0 -81 0.9996 0.9996 500000.0 0.0

tjhb
10,094 post(s)
#20-Oct-16 01:27

Sorry--I put this to one side.

I'll check the error--and hopefully get back to the substances as well, time permitting.

firsttube


1,439 post(s)
#28-Oct-16 15:43

Not sure if this will be of any use, but attached is a project containing our survey control data in both NAD83 (original) and NAD83 (CSRS). You can see the shifts are about 17 cm.

I used FME with the provincial grid shift file to shift the original data to CSRS.

Attachments:
SurveyControl_Original_CSRS.map


"The blessing in life is finding the torture you are comfortable with." - Jerry Seinfeld, 6/26/2013

mdsumner


4,260 post(s)
#09-Sep-16 15:09

Just to throw into the mix: https://youtu.be/VCZQfDl5ejY

A FOSS4G video about a presentation on epsg.io


https://github.com/mdsumner

cab76 post(s)
#14-Aug-16 01:32

Hello Dimitri,

Is that the Coordinate System Dialog box for Radian Studio?

Very nice! It has now the CRS database of EPSG.

Can't wait to try Radian Studio with Manifold 8.

It's August already, when can we start purchasing Radian?

Dimitri


7,413 post(s)
#14-Aug-16 07:10

Well, that will teach me not to confuse the beta forum with other threads. :-)

Sounds like you missed http://www.georeference.org/forum/t129214 - read carefully if interested in Radian.

Could be you've also missed http://www.manifold.net/admin/community_terms.shtml - read that carefully as well if interested in this forum...

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