Tools for MERIS Commisioning Phase

Issue 0.0 July 2000

Intermediate Files analysis tools :

The investigations in the analysis of the intermediate files, which are generated on request during a Level2 processing session with MEGS, were part of the BC task to perform the architecture sensitivity tests on the Level2 processing of the MERIS-ESA ground segment. In order to access the parameters and flags which have been set during a processing session and which are not available in the MERIS Level2 RR product, a set of tools was developed that made it possible to extract and trace these informations on a per pixel basis. The software tools "paramex", "flagtests" and "rulex" -which are especially designed to perform analysis tasks on breakpoint parameters and flags- are described here.

paramex is a parameter extraction tool that reads parameters from intermediate or breakpoint files and writes binary images for each parameter.

flagtests is a tool that:

• compares the cloud flags from a supervised classification image with the appropriate flags that were extracted by paramex
  
• reconstructs the paths that have been taken within the decision table on a per pixel basis

rulex is a tool that finds the rules for misclassifications in dependence of the flags used. It is invoked with SQL-like statements.

The three tools form a kind of unity in the sense that the input of a tool depends on the output of another tool. The following picture shows the two main steps in the processing of the intermediate files:

• the preparation session which consists of the Level2 processing. It takes a Level1b file as input and needs the specification of configuration parameters for the desired intermediate or breakpoint file output. The Level2 product file is not needed for the next step, the analysis session.
• the analysis session which takes an intermediate file from the Level2 processing as input. Note that a secondary input file is needed for the flag comparison part.