[MetaCRS] Datum Transformation Issues

Thu Feb 23 11:46:00 PST 2017

On Wed, Feb 22, 2017 at 11:35 AM, <metacrs-request at lists.osgeo.org> wrote:

>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 22 Feb 2017 17:26:10 +0000
> From: Nick Fordes <nick.fordes at locusview.com>
> To: metacrs at lists.osgeo.org
> Subject: [MetaCRS] Datum Transformation Issues
> Message-ID:
>         <CAD3kFehuxUabsxJum0GqF+J7S2QtbQyA2fn_wFzVoAzqVTC32g@
> mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi -
>
> I am using the Proj4js library and am having trouble successfully
> transforming coordindates from ITRF 2008 (EPSG:5332) to NAD83 (2011)
> (EPSG:6317).
>
> I have bee successful in entering coordinates into the following tool and
> generating results for going from WGS83 (EPSG4326) to NAD83 (2011)
> (EPSG:6317), however, there is no transformation applied.
>
> https://mygeodata.cloud/cs2cs/
>
> Is it possible to provide me with the transformation strings needed to
> accomplish this transformation?
>
> Any guidance would be much appreciated.
>
> Nick Fordes
>
> LocusView Solutions
>
> ------------------------------
>
> Message: 2
> Date: Wed, 22 Feb 2017 12:02:48 -0700
> From: Richard Greenwood <richard.greenwood at gmail.com>
> To: Nick Fordes <nick.fordes at locusview.com>
> Cc: "metacrs at lists.osgeo.org" <metacrs at lists.osgeo.org>
> Subject: Re: [MetaCRS] Datum Transformation Issues
> Message-ID:
>         <CAHBySPZpv=+FiaHgff=zi2cpidMmh8Yhs8w_U-WuHiUKCqeWwg at mail.
> gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On Wed, Feb 22, 2017 at 10:26 AM, Nick Fordes <nick.fordes at locusview.com>
> wrote:
>
> > Hi -
> >
> > I am using the Proj4js library and am having trouble successfully
> > transforming coordindates from ITRF 2008 (EPSG:5332) to NAD83 (2011)
> > (EPSG:6317).
> >
>
> Are you getting an error or incorrect results? The espg definitions for
> 5332 and 6317 are the same (see below) but that's not to say they are
> correct.
>
> # ITRF2008 <5332> +proj=geocent +ellps=GRS80 +units=m +no_defs  <>
> # NAD83(2011) <6317> +proj=geocent +ellps=GRS80 +units=m +no_defs  <>
>
>
> > I have bee successful in entering coordinates into the following tool and
> > generating results for going from WGS83 (EPSG4326) to NAD83 (2011)
> > (EPSG:6317), however, there is no transformation applied.
> >
>
> "NAD" datums are tied to the North American continental plate, "WGS" datums
> are tied to the center of the earth. To get meter or sub-meter accuracy
> transformations you need to use a grid shift transform. Is that what you're
> looking for when you say that no transformation is applied?
>
>
>
>
> --
> Richard W. Greenwood, PLS
> www.greenwoodmap.com
>
> ------------------------------
>
> Message: 3
> Date: Wed, 22 Feb 2017 19:21:37 +0000
> From: Nick Fordes <nick.fordes at locusview.com>
> To: Richard Greenwood <richard.greenwood at gmail.com>
> Cc: "metacrs at lists.osgeo.org" <metacrs at lists.osgeo.org>
> Subject: Re: [MetaCRS] Datum Transformation Issues
> Message-ID:
>         <CAD3kFegVqSZTAahuG7CGjPGrMxQATnWFg2oV61v+wMjPr+ZuZw at mail.
> gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Yes -
>
> I am hoping to achieve a sub-meter transformation between the two datums.
> Also - we would ideally like to go from ITRF 2008 to Is Proj4js an
> appropriate tool to do this?  Can it handle a grid shift transform?
>
> Thanks,
>
> Nick
>
> On Wed, Feb 22, 2017 at 1:02 PM Richard Greenwood <
> richard.greenwood at gmail.com> wrote:
>
> > On Wed, Feb 22, 2017 at 10:26 AM, Nick Fordes <nick.fordes at locusview.com
> >
> > wrote:
> >
> > Hi -
> >
> > I am using the Proj4js library and am having trouble successfully
> > transforming coordindates from ITRF 2008 (EPSG:5332) to NAD83 (2011)
> > (EPSG:6317).
> >
> >
> > Are you getting an error or incorrect results? The espg definitions for
> > 5332 and 6317 are the same (see below) but that's not to say they are
> > correct.
> >
> > # ITRF2008 <5332> +proj=geocent +ellps=GRS80 +units=m +no_defs  <>
> > # NAD83(2011) <6317> +proj=geocent +ellps=GRS80 +units=m +no_defs  <>
> >
> >
> > I have bee successful in entering coordinates into the following tool and
> > generating results for going from WGS83 (EPSG4326) to NAD83 (2011)
> > (EPSG:6317), however, there is no transformation applied.
> >
> >
> > "NAD" datums are tied to the North American continental plate, "WGS"
> > datums are tied to the center of the earth. To get meter or sub-meter
> > accuracy transformations you need to use a grid shift transform. Is that
> > what you're looking for when you say that no transformation is applied?
> >
> >
> > --
> > Richard W. Greenwood, PLS
> > www.greenwoodmap.com
> >
> ------------------------------
>
> Message: 4
> Date: Wed, 22 Feb 2017 12:35:12 -0700
> From: Richard Greenwood <richard.greenwood at gmail.com>
> To: Nick Fordes <nick.fordes at locusview.com>
> Cc: "metacrs at lists.osgeo.org" <metacrs at lists.osgeo.org>
> Subject: Re: [MetaCRS] Datum Transformation Issues
> Message-ID:
>         <CAHBySPa-N6e5MYcsbSJ_huShE2OUn=KA4KyKPJkzexwDAA_
> 6yg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On Wed, Feb 22, 2017 at 12:21 PM, Nick Fordes <nick.fordes at locusview.com>
> wrote:
>
> > Yes -
> >
> > I am hoping to achieve a sub-meter transformation between the two datums.
> > Also - we would ideally like to go from ITRF 2008 to Is Proj4js an
> > appropriate tool to do this?  Can it handle a grid shift transform?
> >
>
> proj4js does not support grid shift transformations. Proj4 does but the
> epsg codes don't always reference the grid shift files. The Proj4 North
> American grid shift files that I'm aware of are tied to State Plane
> coordinate systems. I'm not aware of a grid shift file(s) covering the
> whole continent, which is what it looks like you're wanting?
>
> Rich
>
>
> > Thanks,
> >
> > Nick
> >
> >
> > On Wed, Feb 22, 2017 at 1:02 PM Richard Greenwood <
> > richard.greenwood at gmail.com> wrote:
> >
> >> On Wed, Feb 22, 2017 at 10:26 AM, Nick Fordes <
> nick.fordes at locusview.com>
> >> wrote:
> >>
> >> Hi -
> >>
> >> I am using the Proj4js library and am having trouble successfully
> >> transforming coordindates from ITRF 2008 (EPSG:5332) to NAD83 (2011)
> >> (EPSG:6317).
> >>
> >>
> >> Are you getting an error or incorrect results? The espg definitions for
> >> 5332 and 6317 are the same (see below) but that's not to say they are
> >> correct.
> >>
> >> # ITRF2008 <5332> +proj=geocent +ellps=GRS80 +units=m +no_defs  <>
> >> # NAD83(2011) <6317> +proj=geocent +ellps=GRS80 +units=m +no_defs  <>
> >>
> >>
> >> I have bee successful in entering coordinates into the following tool
> and
> >> generating results for going from WGS83 (EPSG4326) to NAD83 (2011)
> >> (EPSG:6317), however, there is no transformation applied.
> >>
> >>
> >> "NAD" datums are tied to the North American continental plate, "WGS"
> >> datums are tied to the center of the earth. To get meter or sub-meter
> >> accuracy transformations you need to use a grid shift transform. Is that
> >> what you're looking for when you say that no transformation is applied?
> >>
> >>
> >>
> >>
> >> --
> >> Richard W. Greenwood, PLS
> >> www.greenwoodmap.com
> >>
>
> --
> Richard W. Greenwood, PLS
> www.greenwoodmap.com
>
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>
> ------------------------------
>
> End of MetaCRS Digest, Vol 88, Issue 1
> **************************************
>

Nick,

There are no available grid files to convert between ITRF2008 and NAD83
(2011). There is a time-enabled transformation available from the NGS on
this page: https://www.ngs.noaa.gov/CORS/coords.shtml

The time parts would allow you to convert at a particular epoch, but
proj4js (nor proj4 as far as I know) doesn't support the time-parameters.

You can use the base 7 parameters which would take care of the majority of
the difference between the two frames. The website says IGS08 rather than
ITRF2008, but you can treat them as equivalent.

IGS08 --> NAD 83 (2011)
[12 common points]
t0 = 1997.0
x(t0) = 0.99343 m;
y(t0) = -1.90331m;
z(t0) = -0.52655 m
x(t0) = 25.91467 mas;
y(t0) = 9.42645 mas;
z(t0) = 11.59935 mas
s(t0) = 1.71504 · 10-9 (unitless)

This would turn in to

+wgs84=-0.99343,1.90331,0.52655,0.0259,0.0943,0.116,-0.001715

Note: all signs changed to swap direction as from NAD83(2011) to
IGS08/ITRF08/WGS84. Then changed the rotation signs to convert from
coordinate frame method to position vector method. proj4 supports the
latter version only.

Melita
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