THÈS EE - CESBIO - Université Toulouse III - Paul Sabatier

Chapitre 3. Article 1heterogeneous areas. For example, it can be decided that R × N < F 2 (the same inequalityapplies for most speckle filters based on N × N neighbouring windows) which leads tolimitations in the final number of looks:2 2L eF Li8R (26)or to requirements on the spatial resolution:R < F 8 L eL i. (27)Hence for a given L i -look spatial resolution R and a given typical size F of the observedelements, one can derive the maximum equivalent number of looks to be used in Fig. 3 byapplying (26).D. Summary of the resultsThe following key parameters for this analysis have been identified:Satellite system parameters:- Satellite repeat cycle f (days)- Pixel spacing of a L i -look product R(m)- Distributed target ambiguity ratio a (dB)- Channel gain imbalance g (dB) – for PR method only- Radiometric stability s (dB) – for TC method onlyProcessing parameters (multi-looking):- Initial number of looks of the product L i- Equivalent number of looks after spatial multi-looking L eScene description parameters:- Mean size of observed elements F (m)- Duration of monitored phenomenon c (days)- Proportion of class B in land use p(B) (%)Figure 12 illustrates the relations between these parameters and the intermediary parametersintroduced in Section II (namely L, ∆r, p(B), and d), as it has been discussed in the two lastsections.Figure 12. Effects of satellite system parameters (blue), image processing parameters (green)and scene parameters (in red) on the overall probability of error in mapping performance.The intermediary parameters are in grey boxes.92