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Use Cases for assessment of OLCI and SLSTR misregistration

Use Cases for assessment of OLCI and SLSTR misregistration

2015-03-10

This page is related to https://senbox.atlassian.net/browse/SIIITBX-63 . The aim of this issue is to evaluate the misregistration between OLCI L1B and SLSTR L1B products.

We identified the following use cases:

In each use case, it is assumed that SLSTR and OLCI products are opened

Use Case 0: 

  • Load list of reference points (encoded by geocoding)

  • Determine positions in OLCI product for all reference points

  • Determine positions in SLSTR product for alle reference points

Use Case 1:

  • Place a pin at a distinct feature in the OLCI product and retrieve its geolocation (P_olci -> G_olci, with P being an image pixel coordinate (i,j), and G being a geographical point (lat,lon))

  • Place a pin at the same feature in the SLSTR product and retrieve its geolocation (P_slstr -> G_slstr)

  • Compare G_olci and G_slstr <- Note that for this use case information about placement error / placement uncertainty is needed

Use Case 2.1:

  • Place a pin in an OLCI product and retrieve its geolocation (P_olci -> G_olci)

  • Find the position of the geolocation in the SLSTR product (G_olci -> P_slstr)

  • Compare P_olci and P_slstr: Feature distance in pixels

  • Enhancement: Retrieve G_slstr as from P in slstr at correct position. Then: delta_G = g_slstr - g_olci

Use Case 2.2:

  •  First steps as in 2.1

  • Then: Fine the position of the geolocation in the SYN L1C misregistration band (P_olci -> P_slstr_l1c)

 

Use Case 2.2 (from Marc's point of view):

  • open L1C

 

Probable uncertainty / error definitions:

1:

G = GC_olci (P_olci)

P_slstr = GC^-1_slstr (G)

G' = GC_slstr (P_slstr)

P'_olci = GC^-1_olci (G')

delta_G = G - G'

delta_P_olci = P_olci - P_slstr

2:

To be used on SLSTR or OLCI grid

  • Determine four corners and center of a pixel

  • Determine the resulting five geolocations

  • From these, determine relative displacement

Further probable tool: Global Pin

Global pin is displayed in all products which are currently opened in the Sentinel-3 Toolbox.

Pin is assigned:

  • via pixel position

  • via geolocation