<div dir="ltr">Oh, I'd be interested in the cause of this too, please, as a user located in Aus who updated to PROJ 9 not too long ago.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jan 8, 2024 at 10:47 AM Robert Denham via PROJ <<a href="mailto:proj@lists.osgeo.org">proj@lists.osgeo.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">This is probably just an improvement, but I was wondering if someone could help explain minor differences we're observing when transforming coordinates from WGS 84 geographic coordinates to projected coordinates in Australia. <br>
<br>
For example, if I do:<br>
<br>
echo -27.495159464576993 153.02971160860926|<br>
docker run -i --rm --env PROJ_DEBUG=4 --env PROJ_NETWORK=ON osgeo/proj:9.2.0 \<br>
cs2cs epsg:4326 +to epsg:28356<br>
<br>
I get:<br>
<br>
pj_open_lib(proj.ini): call fopen(/usr/share/proj/proj.ini) - succeeded<br>
pj_open_lib(proj.db): call fopen(/usr/share/proj/proj.db) - succeeded<br>
pj_open_lib(au_icsm_GDA94_GDA2020_conformal_and_distortion.tif): call fopen(/usr/share/proj/au_icsm_GDA94_GDA2020_conformal_and_distortion.tif) - succeeded<br>
pj_open_lib(au_icsm_GDA94_GDA2020_conformal_and_distortion.tif): call fopen(/usr/share/proj/au_icsm_GDA94_GDA2020_conformal_and_distortion.tif) - succeeded<br>
502934.82 6958719.00 0.00<br>
Using coordinate operation Inverse of GDA94 to WGS 84 (1) + Map Grid of Australia zone 56<br>
<br>
But if I do the same with version 9.1.1:<br>
<br>
echo -27.495159464576993 153.02971160860926|<br>
docker run -i --rm --env PROJ_DEBUG=4 --env PROJ_NETWORK=ON osgeo/proj:9.1.1 \<br>
cs2cs epsg:4326 +to epsg:28356<br>
<br>
I get a slightly different output:<br>
<br>
502934.23 6958717.61 0.00<br>
<br>
<br>
And a large amount of output (see below)<br>
<br>
I just wanted to check whether this was expected behaviour, and if the difference in the coordinate transformation could be interpreted as an improvement?<br>
I checked other projected coordinates systems, including <br>
<br>
* GDA2020 Zone 56 (EPSG:7856)<br>
* Australian Albers GDA94 (EPSG:3755)<br>
* Australian Albers GDA2020 (EPSG:9473)<br>
<br>
Each of these give slightly different results under proj 9.1.1 and 9.2.0. The only relevant change I could see in proj was EPSG updated to EPSG 10.082 in proj 9.2. I assume this is the source of the differences?<br>
<br>
<br>
Thanks<br>
Robert<br>
<br>
<br>
<br>
(output from cs2cs with proj 9.1.1 follows)<br>
<br>
pj_open_lib(proj.ini): call fopen(/usr/share/proj/proj.ini) - succeeded<br>
pj_open_lib(proj.db): call fopen(/usr/share/proj/proj.db) - succeeded<br>
pj_open_lib(au_icsm_GDA94_GDA2020_conformal_and_distortion.tif): call fopen(/usr/share/proj/au_icsm_GDA94_GDA2020_conformal_and_distortion.tif) - succeeded<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: <br>
pipeline: Pipeline: Building arg list for step no. 0<br>
pipeline: Pipeline: init - proj=axisswap, 2<br>
pipeline: order=2,1<br>
axisswap: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
axisswap: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 0 (proj=axisswap) at 0x562104a31020<br>
pipeline: Pipeline at [0x562104bc7f60]: step at [0x562104a31020] (proj=axisswap) done<br>
pipeline: Pipeline: Building arg list for step no. 1<br>
pipeline: Pipeline: init - proj=unitconvert, 3<br>
pipeline: xy_in=deg<br>
pipeline: xy_out=rad<br>
unitconvert: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
unitconvert: pj_ellipsoid - final: ellps=GRS80<br>
unitconvert: xy_in unit: Degree<br>
unitconvert: xy_out unit: Radian<br>
pipeline: Pipeline: Step 1 (proj=unitconvert) at 0x56210470c510<br>
pipeline: Pipeline at [0x562104bc7f60]: step at [0x56210470c510] (proj=unitconvert) done<br>
pipeline: Pipeline: Building arg list for step no. 2<br>
pipeline: Pipeline: init - proj=utm, 4<br>
pipeline: zone=56<br>
pipeline: south<br>
pipeline: ellps=GRS80<br>
utm: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
utm: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 2 (proj=utm) at 0x562104b90340<br>
pipeline: Pipeline at [0x562104bc7f60]: step at [0x562104b90340] (proj=utm) done<br>
pipeline: Pipeline: 3 steps built. Determining i/o characteristics<br>
axisswap: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
axisswap: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: <br>
pipeline: Pipeline: Building arg list for step no. 0<br>
pipeline: Pipeline: init - proj=unitconvert, 3<br>
pipeline: xy_in=deg<br>
pipeline: xy_out=rad<br>
unitconvert: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
unitconvert: pj_ellipsoid - final: ellps=GRS80<br>
unitconvert: xy_in unit: Degree<br>
unitconvert: xy_out unit: Radian<br>
pipeline: Pipeline: Step 0 (proj=unitconvert) at 0x562104bc82a0<br>
pipeline: Pipeline at [0x562104b87920]: step at [0x562104bc82a0] (proj=unitconvert) done<br>
pipeline: Pipeline: Building arg list for step no. 1<br>
pipeline: Pipeline: init - proj=utm, 4<br>
pipeline: zone=56<br>
pipeline: south<br>
pipeline: ellps=GRS80<br>
utm: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
utm: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 1 (proj=utm) at 0x562104b94000<br>
pipeline: Pipeline at [0x562104b87920]: step at [0x562104b94000] (proj=utm) done<br>
pipeline: Pipeline: 2 steps built. Determining i/o characteristics<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: <br>
pipeline: Pipeline: Building arg list for step no. 0<br>
pipeline: Pipeline: init - proj=axisswap, 2<br>
pipeline: order=2,1<br>
axisswap: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
axisswap: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 0 (proj=axisswap) at 0x562104ac94a0<br>
pipeline: Pipeline at [0x562104c029b0]: step at [0x562104ac94a0] (proj=axisswap) done<br>
pipeline: Pipeline: Building arg list for step no. 1<br>
pipeline: Pipeline: init - proj=unitconvert, 3<br>
pipeline: xy_in=deg<br>
pipeline: xy_out=rad<br>
unitconvert: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
unitconvert: pj_ellipsoid - final: ellps=GRS80<br>
unitconvert: xy_in unit: Degree<br>
unitconvert: xy_out unit: Radian<br>
pipeline: Pipeline: Step 1 (proj=unitconvert) at 0x562104b94d60<br>
pipeline: Pipeline at [0x562104c029b0]: step at [0x562104b94d60] (proj=unitconvert) done<br>
pipeline: Pipeline: Building arg list for step no. 2<br>
pipeline: Pipeline: init - proj=utm, 4<br>
pipeline: zone=56<br>
pipeline: south<br>
pipeline: ellps=GRS80<br>
utm: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
utm: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 2 (proj=utm) at 0x562104b952a0<br>
pipeline: Pipeline at [0x562104c029b0]: step at [0x562104b952a0] (proj=utm) done<br>
pipeline: Pipeline: 3 steps built. Determining i/o characteristics<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: ellps=WGS84<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: <br>
pipeline: Pipeline: Building arg list for step no. 0<br>
pipeline: Pipeline: init - proj=axisswap, 2<br>
pipeline: order=2,1<br>
axisswap: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
axisswap: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 0 (proj=axisswap) at 0x562104b976f0<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b976f0] (proj=axisswap) done<br>
pipeline: Pipeline: Building arg list for step no. 1<br>
pipeline: Pipeline: init - proj=unitconvert, 3<br>
pipeline: xy_in=deg<br>
pipeline: xy_out=rad<br>
unitconvert: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
unitconvert: pj_ellipsoid - final: ellps=GRS80<br>
unitconvert: xy_in unit: Degree<br>
unitconvert: xy_out unit: Radian<br>
pipeline: Pipeline: Step 1 (proj=unitconvert) at 0x562104b97cc0<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b97cc0] (proj=unitconvert) done<br>
pipeline: Pipeline: Building arg list for step no. 2<br>
pipeline: Pipeline: init - proj=push, 2<br>
pipeline: v_3<br>
push: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
push: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 2 (proj=push) at 0x562104b98290<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b98290] (proj=push) done<br>
pipeline: Pipeline: Building arg list for step no. 3<br>
pipeline: Pipeline: init - proj=cart, 2<br>
pipeline: ellps=WGS84<br>
cart: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
cart: pj_ellipsoid - final: ellps=WGS84<br>
pipeline: Pipeline: Step 3 (proj=cart) at 0x562104b98810<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b98810] (proj=cart) done<br>
pipeline: Pipeline: Building arg list for step no. 4<br>
pipeline: Pipeline: init - inv, 10<br>
pipeline: proj=helmert<br>
pipeline: x=0.06155<br>
pipeline: y=-0.01087<br>
pipeline: z=-0.04019<br>
pipeline: rx=-0.0394924<br>
pipeline: ry=-0.0327221<br>
pipeline: rz=-0.0328979<br>
pipeline: s=-0.009994<br>
pipeline: convention=coordinate_frame<br>
helmert: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
helmert: pj_ellipsoid - final: ellps=GRS80<br>
helmert: Helmert parameters:<br>
helmert: x= 0.06155 y= -0.01087 z= -0.04019<br>
helmert: rx= -0.03949 ry= -0.03272 rz= -0.03290<br>
helmert: s= -0.00999 exact=0 convention=coordinate_frame<br>
helmert: dx= 0.00000 dy= 0.00000 dz= 0.00000<br>
helmert: drx= 0.00000 dry= 0.00000 drz= 0.00000<br>
helmert: ds= 0.00000 t_epoch= 0.00000<br>
helmert: Transformation parameters for observation t_obs=0 (t_epoch=0):<br>
helmert: x: 0.06155<br>
helmert: y: -0.01087<br>
helmert: z: -0.04019<br>
helmert: s: -9.994e-09<br>
helmert: rx: -1.91465e-07<br>
helmert: ry: -1.58641e-07<br>
helmert: rz: -1.59494e-07<br>
helmert: theta: 0<br>
helmert: Rotation Matrix:<br>
helmert: | 1 -1.59494e-07 1.58641e-07 |<br>
helmert: | 1.59494e-07 1 -1.91465e-07 |<br>
helmert: | -1.58641e-07 1.91465e-07 1 |<br>
pipeline: Pipeline: Step 4 (inv) at 0x562104b98e90<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b98e90] (inv) done<br>
pipeline: Pipeline: Building arg list for step no. 5<br>
pipeline: Pipeline: init - inv, 3<br>
pipeline: proj=cart<br>
pipeline: ellps=GRS80<br>
cart: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
cart: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 5 (inv) at 0x562104b99560<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b99560] (inv) done<br>
pipeline: Pipeline: Building arg list for step no. 6<br>
pipeline: Pipeline: init - proj=pop, 2<br>
pipeline: v_3<br>
pop: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pop: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 6 (proj=pop) at 0x562104b99ac0<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b99ac0] (proj=pop) done<br>
pipeline: Pipeline: Building arg list for step no. 7<br>
pipeline: Pipeline: init - proj=utm, 4<br>
pipeline: zone=56<br>
pipeline: south<br>
pipeline: ellps=GRS80<br>
utm: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
utm: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 7 (proj=utm) at 0x562104b9a070<br>
pipeline: Pipeline at [0x562104b96660]: step at [0x562104b9a070] (proj=utm) done<br>
pipeline: Pipeline: 8 steps built. Determining i/o characteristics<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
pipeline: pj_ellipsoid - final: <br>
pipeline: Pipeline: Building arg list for step no. 0<br>
pipeline: Pipeline: init - proj=axisswap, 2<br>
pipeline: order=2,1<br>
axisswap: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
axisswap: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 0 (proj=axisswap) at 0x562104b9b790<br>
pipeline: Pipeline at [0x562104b9a890]: step at [0x562104b9b790] (proj=axisswap) done<br>
pipeline: Pipeline: Building arg list for step no. 1<br>
pipeline: Pipeline: init - proj=unitconvert, 3<br>
pipeline: xy_in=deg<br>
pipeline: xy_out=rad<br>
unitconvert: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
unitconvert: pj_ellipsoid - final: ellps=GRS80<br>
unitconvert: xy_in unit: Degree<br>
unitconvert: xy_out unit: Radian<br>
pipeline: Pipeline: Step 1 (proj=unitconvert) at 0x562104b9bd60<br>
pipeline: Pipeline at [0x562104b9a890]: step at [0x562104b9bd60] (proj=unitconvert) done<br>
pipeline: Pipeline: Building arg list for step no. 2<br>
pipeline: Pipeline: init - inv, 3<br>
pipeline: proj=hgridshift<br>
pipeline: grids=au_icsm_GDA94_GDA2020_conformal_and_distortion.tif<br>
hgridshift: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
hgridshift: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 2 (inv) at 0x562104b9c380<br>
pipeline: Pipeline at [0x562104b9a890]: step at [0x562104b9c380] (inv) done<br>
pipeline: Pipeline: Building arg list for step no. 3<br>
pipeline: Pipeline: init - proj=utm, 4<br>
pipeline: zone=56<br>
pipeline: south<br>
pipeline: ellps=GRS80<br>
utm: pj_ellipsoid - final: a=6378137.000 f=1/298.257, errno=0<br>
utm: pj_ellipsoid - final: ellps=GRS80<br>
pipeline: Pipeline: Step 3 (proj=utm) at 0x562104b9c950<br>
pipeline: Pipeline at [0x562104b9a890]: step at [0x562104b9c950] (proj=utm) done<br>
pipeline: Pipeline: 4 steps built. Determining i/o characteristics<br>
Using coordinate operation Inverse of GDA94 to WGS 84 (3) + Map Grid of Australia zone 56<br>
pj_open_lib(au_icsm_GDA94_GDA2020_conformal_and_distortion.tif): call fopen(/usr/share/proj/au_icsm_GDA94_GDA2020_conformal_and_distortion.tif) - succeeded<br>
502934.23 6958717.61 0.00<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
R<br>
<br>
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</blockquote></div>