[Proj] TM06 for Portugal
Roger Oberholtzer
roger at opq.se
Tue Jun 8 23:07:25 PDT 2010
On Tue, 2010-06-08 at 09:40 +0200, Mikael Rittri wrote:
> Roger Oberholtzer wrote:
>
> > How would you convert WGS84 lat/long into TM06
> > northing/easting? I know that WGS84 is so close
> > to ETR89 here that one 'could' use the WGS84 values
> > in the transform from ETRS89 to TM06. But how
> > would I do it the 'proper' way with proj?
>
> For this purpose, there are seven-parameter
> transformations that are time-dependent (since
> the ETRS89 follows the contintental drift of
> Eurasia, while WGS84 does not).
>
> The British Ordnance Survey cites the following
> datum shift from ITRS2005 to ETRS89:
>
> tX = 0.056 m
> tY = 0.048 m
> tZ = -0.037 m
> rX = 0.000054 sec * deltatime
> rY = 0.000518 sec * deltatime
> rZ = -0.000781 sec * deltatime
> s = 0 ppm
>
> where deltatime is the difference, in years, between
> the time when the ITRS2005 coordinates were observed,
> and the fixed epoch of ETRS89, which is 1989.0.
> http://www.ordnancesurvey.co.uk/oswebsite/gps/information/coordinatesyst
> emsinfo/guidecontents/guide6.html
>
> For example, today its June 8, 2010, which is the
> 159th day of the year, so expressed in decimal years
> it is today 2010 + 159/365 = 2010.44. So deltatime
> would be 2010.44 - 1989.0 = 21.44.
>
> I believe ITRS2005 can be regarded as equivalent to
> WGS84 with centimeter accuracy (although I am a bit
> out of my depth here). If so, the datum shift can
> be interpreted as going from from WGS84 to ETRS89,
> and in Proj.4 we want to express it in the opposite
> direction. So we reverse all signs. (The Ordnance
> Survey uses the same rotation sign convention as
> Proj.4, so that is one worry less.)
>
> So, as an accurate datum shift for ETRS89, we get
>
> +towgs84=-0.056,-0.048,0.037, < -0.000054 * 21.44 >, < -0.000518 *
> 21.44 >, < 0.000781 * 21.44 >, 0
>
> or
>
> +towgs84=-0.056,-0.048,0.037,-0.00115776,-0.01110592,0.01674464,0
I have tried that. I now get the following. The Ref lines are the data I
have been provided. The Calc line is what I get with the statement
above. It was an improvement.
PATAIAS:
Ref: Latitude: 39.6871677778 Longitude: -9.0025450000 Altitude: 0.000
Ref: Easting: -74582.612 Northing: 2460.852 Altitude: 0.000
Calc: Easting: -74583.114 Northing: 2460.470 Altitude: 0.012 0.631 meters from Ref
Inv: Latitude: 39.6871712662 Longitude: -9.0025391909 Altitude: -0.691
Diff: -0.0000034884 -0.0000058091 0.691
BARROCAL 2:
Ref: Latitude: 40.7508825000 Longitude: -7.1747969444 Altitude: 0.000
Ref: Easting: 80930.409 Northing: 120655.780 Altitude: 0.000
Calc: Easting: 80930.751 Northing: 120654.564 Altitude: 0.012 1.263 meters from Ref
Inv: Latitude: 40.7508934786 Longitude: -7.1748008314 Altitude: -0.705
Diff: -0.0000109786 0.0000038870 0.705
BATEL:
Ref: Latitude: 38.7409769444 Longitude: -8.9387027778 Altitude: 0.000
Ref: Easting: -70039.439 Northing: -102638.301 Altitude: 0.000
Calc: Easting: -70040.321 Northing: -102638.468 Altitude: 0.013 0.897 meters from Ref
Inv: Latitude: 38.7409785180 Longitude: -8.9386926531 Altitude: -0.750
Diff: -0.0000015735 -0.0000101246 0.750
CASCALHEIRA:
Ref: Latitude: 38.6597175000 Longitude: -8.4014394444 Altitude: 0.000
Ref: Easting: -23355.156 Northing: -111932.822 Altitude: 0.000
Calc: Easting: -23355.845 Northing: -111933.048 Altitude: 0.014 0.725 meters from Ref
Inv: Latitude: 38.6597195517 Longitude: -8.4014315342 Altitude: -0.778
Diff: -0.0000020517 -0.0000079102 0.778
CRASTA ALTA:
Ref: Latitude: 39.9583455556 Longitude: -8.8866494444 Altitude: 0.000
Ref: Easting: -64387.200 Northing: 32480.388 Altitude: 0.000
Calc: Easting: -64387.527 Northing: 32480.218 Altitude: 0.012 0.368 meters from Ref
Inv: Latitude: 39.9583471081 Longitude: -8.8866456341 Altitude: -0.680
Diff: -0.0000015525 -0.0000038104 0.680
FANADIA:
Ref: Latitude: 39.3653083333 Longitude: -9.0732191667 Altitude: 0.000
Ref: Easting: -81019.923 Northing: -33212.510 Altitude: 0.000
Calc: Easting: -81019.052 Northing: -33213.931 Altitude: 0.012 1.667 meters from Ref
Inv: Latitude: 39.3653210517 Longitude: -9.0732294452 Altitude: -0.707
Diff: -0.0000127183 0.0000102785 0.707
MARCO GRANDE:
Ref: Latitude: 39.1389694444 Longitude: -9.3360900000 Altitude: 0.000
Ref: Easting: -104009.123 Northing: -58072.988 Altitude: 0.000
Calc: Easting: -104007.727 Northing: -58074.495 Altitude: 0.012 2.054 meters from Ref
Inv: Latitude: 39.1389828464 Longitude: -9.3361063738 Altitude: -0.709
Diff: -0.0000134020 0.0000163738 0.709
NASCE ÁGUA:
Ref: Latitude: 39.2484761111 Longitude: -7.2524100000 Altitude: 0.000
Ref: Easting: 76024.744 Northing: -46237.481 Altitude: 0.000
Calc: Easting: 76024.440 Northing: -46236.723 Altitude: 0.014 0.817 meters from Ref
Inv: Latitude: 39.2484692585 Longitude: -7.2524065676 Altitude: -0.792
Diff: 0.0000068526 -0.0000034324 0.792
SALMANHA:
Ref: Latitude: 40.1534963889 Longitude: -8.8332422222 Altitude: 0.000
Ref: Easting: -59653.458 Northing: 54112.120 Altitude: 0.000
Calc: Easting: -59653.634 Northing: 54112.029 Altitude: 0.012 0.198 meters from Ref
Inv: Latitude: 40.1534972202 Longitude: -8.8332401686 Altitude: -0.671
Diff: -0.0000008313 -0.0000020536 0.671
SANTA CRUZ:
Ref: Latitude: 41.6743830556 Longitude: -8.3312663889 Altitude: 0.000
Ref: Easting: -16498.151 Northing: 222796.720 Altitude: 0.000
Calc: Easting: -16501.304 Northing: 222793.861 Altitude: 0.010 4.256 meters from Ref
Inv: Latitude: 41.6744088589 Longitude: -8.3312286018 Altitude: -0.601
Diff: -0.0000258033 -0.0000377871 0.601
These are the calculations with +towgs84=0,0,0,0,0,0,0:
PATAIAS:
Ref: Latitude: 39.6871677778 Longitude: -9.0025450000 Altitude: 0.000
Ref: Easting: -74582.612 Northing: 2460.852 Altitude: 0.000
Calc: Easting: -74582.779 Northing: 2460.870 Altitude: 0.000 0.168 meters from Ref
Inv: Latitude: 39.6871676346 Longitude: -9.0025430513 Altitude: 0.000
Diff: 0.0000001432 -0.0000019487 0.000
BARROCAL 2:
Ref: Latitude: 40.7508825000 Longitude: -7.1747969444 Altitude: 0.000
Ref: Easting: 80930.409 Northing: 120655.780 Altitude: 0.000
Calc: Easting: 80931.080 Northing: 120654.973 Altitude: 0.000 1.049 meters from Ref
Inv: Latitude: 40.7508898317 Longitude: -7.1748047793 Altitude: 0.000
Diff: -0.0000073317 0.0000078348 0.000
BATEL:
Ref: Latitude: 38.7409769444 Longitude: -8.9387027778 Altitude: 0.000
Ref: Easting: -70039.439 Northing: -102638.301 Altitude: 0.000
Calc: Easting: -70039.980 Northing: -102638.068 Altitude: 0.000 0.589 meters from Ref
Inv: Latitude: 38.7409748871 Longitude: -8.9386965301 Altitude: 0.000
Diff: 0.0000020573 -0.0000062476 0.000
CASCALHEIRA:
Ref: Latitude: 38.6597175000 Longitude: -8.4014394444 Altitude: 0.000
Ref: Easting: -23355.156 Northing: -111932.822 Altitude: 0.000
Calc: Easting: -23355.504 Northing: -111932.645 Altitude: 0.000 0.390 meters from Ref
Inv: Latitude: 38.6597159166 Longitude: -8.4014354406 Altitude: 0.000
Diff: 0.0000015834 -0.0000040039 0.000
CRASTA ALTA:
Ref: Latitude: 39.9583455556 Longitude: -8.8866494444 Altitude: 0.000
Ref: Easting: -64387.200 Northing: 32480.388 Altitude: 0.000
Calc: Easting: -64387.194 Northing: 32480.619 Altitude: 0.000 0.231 meters from Ref
Inv: Latitude: 39.9583434751 Longitude: -8.8866494969 Altitude: 0.000
Diff: 0.0000020804 0.0000000525 0.000
FANADIA:
Ref: Latitude: 39.3653083333 Longitude: -9.0732191667 Altitude: 0.000
Ref: Easting: -81019.923 Northing: -33212.510 Altitude: 0.000
Calc: Easting: -81018.715 Northing: -33213.532 Altitude: 0.000 1.582 meters from Ref
Inv: Latitude: 39.3653174211 Longitude: -9.0732333063 Altitude: 0.000
Diff: -0.0000090877 0.0000141397 0.000
MARCO GRANDE:
Ref: Latitude: 39.1389694444 Longitude: -9.3360900000 Altitude: 0.000
Ref: Easting: -104009.123 Northing: -58072.988 Altitude: 0.000
Calc: Easting: -104007.389 Northing: -58074.096 Altitude: 0.000 2.058 meters from Ref
Inv: Latitude: 39.1389792184 Longitude: -9.3361102241 Altitude: 0.000
Diff: -0.0000097740 0.0000202241 0.000
NASCE ÁGUA:
Ref: Latitude: 39.2484761111 Longitude: -7.2524100000 Altitude: 0.000
Ref: Easting: 76024.744 Northing: -46237.481 Altitude: 0.000
Calc: Easting: 76024.778 Northing: -46236.315 Altitude: 0.000 1.166 meters from Ref
Inv: Latitude: 39.2484656142 Longitude: -7.2524105282 Altitude: 0.000
Diff: 0.0000104969 0.0000005282 0.000
SALMANHA:
Ref: Latitude: 40.1534963889 Longitude: -8.8332422222 Altitude: 0.000
Ref: Easting: -59653.458 Northing: 54112.120 Altitude: 0.000
Calc: Easting: -59653.301 Northing: 54112.430 Altitude: 0.000 0.347 meters from Ref
Inv: Latitude: 40.1534935866 Longitude: -8.8332440316 Altitude: 0.000
Diff: 0.0000028023 0.0000018094 0.000
SANTA CRUZ:
Ref: Latitude: 41.6743830556 Longitude: -8.3312663889 Altitude: 0.000
Ref: Easting: -16498.151 Northing: 222796.720 Altitude: 0.000
Calc: Easting: -16500.981 Northing: 222794.265 Altitude: 0.000 3.747 meters from Ref
Inv: Latitude: 41.6744052195 Longitude: -8.3312324714 Altitude: 0.000
Diff: -0.0000221639 -0.0000339175 0.000
> At least today.
>
> There may be more recent versions of this kind of
> transformation. I believe they are known as
> "14 parameter transformations" in general.
> Also, there may be regional versions that are
> more accurate for Portugal.
I am wondering if this is the case. I have not been successful getting
this information. I think the software they use is a black box to them,
and so they do not know where to look to find the settings they really
use. Sigh...
>
> Disclaimer: I am not a geodesist, and I haven't
> tested this datum shift on any real data.
>
> Mikael Rittri
> Carmenta AB
> Sweden
> www.carmenta.com
>
> -----Original Message-----
> From: proj-bounces at lists.maptools.org
> [mailto:proj-bounces at lists.maptools.org] On Behalf Of Roger Oberholtzer
> Sent: Monday, June 07, 2010 1:38 PM
> To: PROJ.4 and general Projections Discussions
> Subject: Re: [Proj] TM06 for Portugal
>
> (full text at
> http://lists.maptools.org/pipermail/proj/2010-June/005233.html )
>
--
Roger Oberholtzer
OPQ Systems / Ramböll RST
Ramböll Sverige AB
Krukmakargatan 21
P.O. Box 17009
SE-104 62 Stockholm, Sweden
Office: Int +46 10-615 60 20
Mobile: Int +46 70-815 1696
More information about the Proj
mailing list