Misalignment when loading SNAP-exported OCLI GeoTiff into GIS

[jmendrok]

Hej,

I have exported a Sentinel-3 OCLI RGB view as GeoTiff using ‘export view as image’ as described in this EUMETSAT tutorial (also featured on the STEP tutorial page). When I open it in ArcGIS and add a basemap layer, the basemap and OCLI image do not align.

I wonder, what I’m doing wrong or whether there are issues with the georeferencing coming with the GeoTiff. Is plainly exporting as GeoTiff maybe not enough, and I first need to reproject as suggested in that topic?

Georeference/Reprojecting Sentinel 3A Level 2 OLCI ChL_OC4ME

Simply open the xfdumanifest.xml in SNAP. Do the reprojection (Raster/Geometric Operations/Reprojection) and select the reprojection you like. Click the option not to reprojection the tie-points. Don’t save the product to disk yet. Remove all bands except the OLCI CHL_OC4ME band. You can simply select the bands in the product explorer and hit the <DEL>-key. Actually, this should be possible by the Subset operation (Raster/Subset in the menu) but there is a little bug at the moment. That’s why …

I’m quite an ArcGIS newbie (and my georeferencing/geodatum/projection knowledge is fairly rusty as well), so I admit that my mistake might as well be there. So far, I had the impression though, that if data comes with proper georeference info, ArcGIS takes care of it and adjusts projection and presentation accordingly on the fly. And I can indeed change the projection and the presentation of both image and basemap is adapted. Just, the misalignment remains.

Anyone with some hints or suggestions?

[jmendrok]

Ok, things look much better when reprojecting the S3-OLCI data to ‘Geographical Lat/Lon (WGS84)’:

I still do not really understand, though, what is going on, why the original does not fit. Particularly confusing that both, original and reprojected dataset, have the same spatial reference attached to it according to ArcMap (left is the reprojected (sub)set, right the original direct geotiff export) :