#3930: reprojection error in r.proj / GRASS 7.8.1 -- N-S-coordinates interchanged
with W-E
--------------------------------+---------------------------------
Reporter: guilo | Owner: grass-dev@…
Type: defect | Status: new
Priority: normal | Milestone:
Component: Projections/Datums | Version: git-releasebranch78
Keywords: | CPU: x86-64
Platform: Linux |
--------------------------------+---------------------------------
= Description =
There is observed a serious error in map reprojection, using r.proj,
resulting in an interchange of N-S-coordinates with those of East-West.
The error occurs in GRASS version 7.8 (proj4 version 6.2, gdal version
2.42), in the reprojection with r.proj, from a newly created source map
projection, to an existent target map projection. Repeating the same
procedure, but using a formerly created source map projection (same
projection, but prior to GRASS 7.6), the maps are reprojected in a correct
way.
Under GRASS 7.6, the reprojection procedure is carried out correctly, for
both source map projection versions.
== Minimal working example ==
The example is based on the reprojection of a small section of a Landsat 8
image, from WGS84 / UTM 20N projection, into POSGAR 2007 / Argentina 4
projection. The file "testLandsatUTM20Nsection.tif" is attached to this
mail.
1. system: debian linux 10 (buster), gdal: 2.42, proj4: 6.2
2. new source map projection, created under GRASS 7.8:
(Thu Oct 3 07:22:23 2019)\\
g.proj -p\\
-PROJ_INFO-------------------------------------------------\\
name : WGS 84 / UTM zone 20N\\
datum : wgs84\\
ellps : wgs84\\
proj : utm\\
zone : 20\\
no_defs : defined\\
towgs84 : 0.000,0.000,0.000\\
-PROJ_EPSG-------------------------------------------------\\
epsg : 32620\\
-PROJ_UNITS------------------------------------------------\\
unit : meter\\
units : meters\\
meters : 1\\
(Thu Oct 3 07:22:23 2019) Command finished (0 sec)
3. old source map projection, creation with GRASS prior to 7.6)
(Thu Oct 3 07:31:21 2019)\\
g.proj -p\\
-PROJ_INFO-------------------------------------------------\\
name : Universal Transverse Mercator\\
proj : utm\\
datum : wgs84\\
ellps : wgs84\\
zone : 20\\
no_defs : defined\\
towgs84 : 0.000,0.000,0.000\\
-PROJ_UNITS------------------------------------------------\\
unit : meter\\
units : meters\\
meters : 1\\
(Thu Oct 3 07:31:22 2019) Command finished (0 sec)
4. target map projection:
(Thu Oct 3 07:19:24 2019)\\
g.proj -p\\
-PROJ_INFO-------------------------------------------------\\
name : POSGAR 2007 / Argentina 4\\
ellps : grs80\\
proj : tmerc\\
lat_0 : -90\\
lon_0 : -63\\
k : 1\\
x_0 : 4500000\\
y_0 : 0\\
towgs84 : 0,0,0,0,0,0,0\\
no_defs : defined\\
-PROJ_EPSG-------------------------------------------------\\
epsg : 5346\\
-PROJ_UNITS------------------------------------------------\\
unit : meter\\
units : meters\\
meters : 1\\
(Thu Oct 3 07:19:24 2019) Command finished (0 sec)
5. Reprojection results:
5.1 correct reprojection with GRASS 7.6.2, from both, old and new
source projection
a) from old source projection
(Sat Nov 2 05:54:58 2019)\\
r.proj -p location=L8utm20N mapset=PERMANENT
input=testLandsatUTM20Nsection\\
Source cols: 500\\
Source rows: 200\\
Local north: 6959148.60238428\\
Local south: 6953146.20142391\\
Local west: 4310724.28971634\\
Local east: 4325730.29211732\\
Input map <testLandsatUTM20Nsection@PERMANENT> in location
<L8utm20N>:\\
(Sat Nov 2 05:54:59 2019) Command finished (0 sec)\\
b) from new source projection
r.proj -p location=L8utm20N2019 input=testLandsatUTM20Nsection\\
Source cols: 500\\
Source rows: 200\\
Local north: 6959148.60238428\\
Local south: 6953146.20142391\\
Local west: 4310724.28971634\\
Local east: 4325730.29211732\\
Input map <testLandsatUTM20Nsection@PERMANENT> in location
<L8utm20N2019>:\\
(Sat Nov 2 05:56:10 2019) Command finished (0 sec)\\
5.2 incorrect reprojection in GRASS 7.8.1, from new source projection
N/S coordinates are interchanged with those of W/E
r.proj -p location=L8utm20N2019 input=testLandsatUTM20Nsection\\
Input map <testLandsatUTM20Nsection@PERMANENT> in location
<L8utm20N2019>:\\
Source cols: 500\\
Source rows: 200\\
Local north: 4325730.29211624\\
Local south: 4310724.28971522\\
Local west: 6953146.20150881\\
Local east: 6959148.60246907\\
(Sat Nov 2 06:01:24 2019) Command finished (0 sec)\\
5.3 correct reprojection in GRASS 7.8.1, from old source projection
(Sat Nov 2 05:59:57 2019)\\
r.proj -p location=L8utm20N mapset=PERMANENT
input=testLandsatUTM20Nsection\\
Source cols: 500\\
Source rows: 200\\
Local north: 6959148.60238337\\
Local south: 6953146.201423\\
Local west: 4310724.28971655\\
Local east: 4325730.29211746\\
Input map <testLandsatUTM20Nsection@PERMANENT> in location <L8utm20N>:\\
(Sat Nov 2 05:59:58 2019) Command finished (0 sec)\\
--
Ticket URL: <https://trac.osgeo.org/grass/ticket/3930>
GRASS GIS <https://grass.osgeo.org>