I am pretty confused by projecting data from one coordinate system to another, especially if multiple transformation options are available (ArcGIS 10.4).

I downloaded Landsat LT5 data (origCS = GSC: WGS84, EPSG:4326) and I reprojected it to final PCS: S-JTSK (desiredCS = EPSG: 5514). Multiple transformations are available in ArcGIS:

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I therefore applied the NGA transformation (S_JTSK_To_WGS_1984_NGA, called _nga) and further processed and classified my rasters.

Now, I am thinking to change the way how Landsat has been projected, i.e change transformation #1 to transformation #2, keeping the original (WGS84) and final coordinate systems (S-JTSK) the same.

If that is possible and "legal", what is correct approach to do that?

As processing of my projected rasters has taken lot of time, I don't want to start again with the raw Landsat data, and I prefer to play around with transformation of classified rasters.

My thoughts how to change transformations of final rasters are:

  1. simply transform the raster_nga to raster_t2 (from one transformation to another, staying in S-JTSK) - is this possible?
  2. project one landsat_wgs to lansat_t2 (by transformation 2) and use it as master scene to resample final classified rasters?
  3. something else??
  4. is this needed or even not at all??

I am working on study area of size 400 km2, using single Lansat scene per time.

  • Please ask only one question per Question – Vince Nov 22 '17 at 0:24
  • 2
    The rasters that are now in S-JTSK are already there. If you want to reproject to WGS84 just use a different transformation. If you want to change how you got from WGS84 to S-JTSK you would have to reproject the rasters with the new transformation. – mkennedy Nov 22 '17 at 1:02

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