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ceos-org / ceos-ard

Repository for CEOS Analysis Ready Data (CEOS-ARD), including Product Family Specifications (PFSs)
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Geometric correction necessity (1.7) #20

Open mattsymbios opened 8 months ago

mattsymbios commented 8 months ago

Target wording should accommodate scenarios where a geometric correction is not required

strobpr commented 8 months ago

we should distinguish between two "geometric" requirements here:

a) geolocating (here: determination of the geographic location of an observation/sample/pixel) This is a threshold requirement for any geospatial ARD, we can discuss to narrow down the locating options (specific CRSs like WGS84 etc.)

b) georectification/ortorectification (here: the correction of sample locations to achieve some sort of geometric regularity, e.g a regular 2D geographic grid

In most cases this step inevitably requires resampling of the original observations. It will only foster interoperability ('analysis readiness') if the respective grid is shared with other datasets with which interoperability is desired. We might therefore impose restrictions on which grids are allowed. These specific (harmonised) grid should then become part of a threshold requirement. A rectification to a grid, arbitrarily chosen by the provider, is generally not desirable. In this case requirement a) is sufficient and should ideally be accompanied by:

c) resampling method (here: a mathematical method to derive values for locations other than the ones observed) As plenty such methods (NN, bicubic, ...) exist and are usually applicable with the known caveats, this requirement might remain a goal.