ogr2ogr: -s_srs and -a_srs trouble

[peifer]

I must be completely braindead, but I can't figure out what happens below. The actual task is to convert a shapefile into KML. The shapefile has no .prj file, but I know the SRS is EPSG:2169.

Q1: Why is there no coordinate transformation in case 1). I thought -s_srs defines/overrides the source SRS

Q2: Why does it work as expected with -a_srs in case 2 ? I thought -a_srs assigns an output SRS.

Q3: Why is there no coordinate transformation in case 3), while creating a 2nd layer in the KML file, using -a_srs ?

Q4: Why does it again work as expected in case 4), but only after adding both -s_srs epsg:2169 and -t_srs epsg:4326 ? (-t_srs epsg:4326 is usually not needed with the KML driver)

$ ### 1
$
$ ogr2ogr -s_srs epsg:2169 -f kml out.kml LUDH10_290910p.shp -select SITECODE -where fid=1 -nln layer1
Shape: DBF Codepage = LDID/87 for LUDH10_290910p.shp
Shape: Treating as encoding 'ISO-8859-1'.
OGR: OGROpen(LUDH10_290910p.shp/0x1b430e0) succeeded as ESRI Shapefile.
KML: Attempt to create: out.kml
ERROR 1: Latitude 96753.945256 is invalid. Valid range is [-90,90]. This warning will not be issued any more
Warning 1: Longitude 103923.921915 has been modified to fit into range [-180,180]. This warning will not be issued any more
OGR2OGR: 1 features written in layer 'layer1'
Shape: 12 features read on layer 'LUDH10_290910p'.
GDAL: In GDALDestroy - unloading GDAL shared library.
$
$
$ ### 2
$
$ ogr2ogr -a_srs epsg:2169 -f kml out.kml LUDH10_290910p.shp -select SITECODE -where fid=1 -nln layer1
Shape: DBF Codepage = LDID/87 for LUDH10_290910p.shp
Shape: Treating as encoding 'ISO-8859-1'.
OGR: OGROpen(LUDH10_290910p.shp/0xa130e0) succeeded as ESRI Shapefile.
KML: Attempt to create: out.kml
OGRCT: Source: +proj=tmerc +lat_0=49.83333333333334 +lon_0=6.166666666666667 +k=1 +x_0=80000 +y_0=100000 +ellps=intl +towgs84=-189.681,18.3463,-42.7695,-0.33746,-3.09264,2.53861,0.4598 +units=m +no_defs
OGRCT: Target: +proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs
OGR2OGR: 1 features written in layer 'layer1'
Shape: 12 features read on layer 'LUDH10_290910p'.
GDAL: In GDALDestroy - unloading GDAL shared library.
$
$
$ ### 3
$
$ ogr2ogr -a_srs epsg:2169 -f kml out.kml LUDH10_290910p.shp -select SITECODE -where fid=1 -nln layer2 -update -append
Shape: DBF Codepage = LDID/87 for LUDH10_290910p.shp
Shape: Treating as encoding 'ISO-8859-1'.
OGR: OGROpen(LUDH10_290910p.shp/0x13540e0) succeeded as ESRI Shapefile.
OGR: OGROpen(out.kml/0x1355c60) succeeded as LIBKML.
OGR2OGR: 1 features written in layer 'layer2'
Shape: 12 features read on layer 'LUDH10_290910p'.
GDAL: In GDALDestroy - unloading GDAL shared library.
$
$
$ ### 4
$
$ ogr2ogr -s_srs epsg:2169 -t_srs epsg:4326 -f kml out.kml LUDH10_290910p.shp -select SITECODE -where fid=1 -nln layer3 -update -append
Shape: DBF Codepage = LDID/87 for LUDH10_290910p.shp
Shape: Treating as encoding 'ISO-8859-1'.
OGR: OGROpen(LUDH10_290910p.shp/0x24980e0) succeeded as ESRI Shapefile.
OGR: OGROpen(out.kml/0x2499cb0) succeeded as LIBKML.
OGRCT: Source: +proj=tmerc +lat_0=49.83333333333334 +lon_0=6.166666666666667 +k=1 +x_0=80000 +y_0=100000 +ellps=intl +towgs84=-189.681,18.3463,-42.7695,-0.33746,-3.09264,2.53861,0.4598 +units=m +no_defs
OGRCT: Target: +proj=longlat +datum=WGS84 +no_defs
OGR2OGR: 1 features written in layer 'layer3'
Shape: 12 features read on layer 'LUDH10_290910p'.
GDAL: In GDALDestroy - unloading GDAL shared library.
$

[Even Rouault]

Questions are not appropriate for Trac tickets. The should be asked on the ML where they have more visibility and where answers can be seen by more people.