Hi Jordi,
gdal is saying that :
- your image has no coordinate system, which is okay for an image in
sensor geomtry
- the GCPs in your image are defined in the EPSG:4326 coordinate system,
which means that the ground coordinated of your GCPs are expressed in
plain lon/lat .
OTB needs a sensor model to reproject your image. Check with
"otbcli_ReadImageInfo -keywordlist 1" if there is a RPC model detected.
Otherwise, you could try to estimate an RPC model from the GCPs
(application GenerateRPCSensorModel).
Regards,
Guillaume
On 03/13/2015 03:06 PM, Jordi Inglada wrote:
Hi all,
I have been trying to reproject Sentinel-1 imagery with OTB and I am having
difficulties.
I am using IW-GRD (non-complex) images which are in geotiff format and contain
GCPs. It's been a long time since I worked with image projections, so I may be
misunderstanding things.
First of all, OTB tells me that:
Estimated ground spacing (in meters): [900.033,328.958]
which is definitely wrong. Having a look at the meta-data (with both
ReadImageInfo and gdalinfo) I get coherent results in terms of GCPs,
projections and sizes, but there are things which seem suspicious like the fact
that there is no coordinate system defined and that there are 2 EPSG codes
(gdalinfo):
----------------
Size is 25397, 20713
Coordinate System is `'
GCP Projection =
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["unnamed",6378137,298.257223560493,
AUTHORITY["EPSG","4326"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4326"]]
GCP[ 0]: Id=1, Info=
(0,0) -> (3.35838036356165,44.0387571612464,573.503620014526)
etc.
-----------------
and ReadImageInformation says the same but gives me funny origin and spacing:
-----------------
Origin : [0.5,0.5]
Spacing : [1,1]
Estimated ground spacing (in meters): [900.033,328.958]
-----------------
For geometry and EPSG-codes experts, do you think that there are problems with
the meta-data?
I could maybe fix the problem with gdal_edit?
Has anyone already worked with Sentinel-1 geometry corrections using
gdal/ossim/OTB?
Thank you.
Jordi
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