EOMasters Toolbox Basic

Band Maths Extensions

These extensions provide new functionalities for the Band Maths expressions. The following functionalities are available:

• Valid
  This attribute returns true if the current pixel is valid. Valid means that the pixel value is not equal to the no-data value (if used) and the pixel matches the valid-pixel expression of the band. NaN values are considered as valid except the no-data value of the band is set to NaN. It is used as follows:
  <band-name>.valid   e.g.,  --> Oa10_radiance.valid
  
• Map Coordinates
  It is already possible to get the pixel (X,Y) and the geographic coordinates (LAT,LON) in a Band Maths Expression. With these two new symbols (MAPX, MAPY) you can also access the map coordinates of the product scene. The returned coordinate represents the center of the pixel. If the scene is not reprojected to a map, the geographic coordinates are returned. The X and Y map coordinates are returned by the symbols: MAPX and MAPY
  
• Note!
  The valid attribute and the map attributes are not selectable from the drop-down boxes in the GUI. But they can be used in the expression.
• AreValid Function
  Similar to the valid attribute, this function returns true if all provided bands are valid.
  Only bands are allowed as arguments. It is used as follows:
  areValid(<band_name>, <band_name>, ...)   e.g.,  --> areValid(B2, B3, B4, B8)
  
• Min, Max and Mean
  These functions return the minimum, maximum and mean of the provided inputs. The functions exclude NaN, infinite and invalid values from the computation. They are used as follows:
  <func>(<value>, <value>, ...)
  
  • minOf: Returns the minimum of the provided inputs values.
    e.g., --> minOf(0.7, <B7>, <B8>, <B8A>)
  • maxOf: Returns the maximum of the provided inputs values.
    e.g., --> maxOf(<B1>, <B2>, 0.2)
  • meanOf: Returns the mean value of the provided inputs values.
    e.g., --> meanOf(<B1>, <B2>, <B3>, <B4>, <B5>)
• Index of Min and Max
  These functions return the index of the minimum or maximum value within the list provided input values. The functions pixels values which are invalid. They are used as follows:
  <func>(<value>, <value>, ...)
  
  • indexOfMin : Returns the index of the minimum value among the inputs values.
    e.g., --> indexOfMin(0.7, <B7>, <B8>, <B1>)
  • indexOfMax: Returns the maximum of the provided inputs values.
    e.g., --> indexOfMax(<B1>, <B2>, 0.2)
• Window Functions
  The window is centered on the current pixel and the window size must be 3, 5 or 7. NaN and invalid values are ignored. If all values in the window are NaN or invalid, the result is NaN. The functions are used as follows:
  wnd(<band_name>, <window_size>, "<function>") The following functions are available:
  
  • sum: Sum of all valid pixels in the window
    e.g.,  --> wnd(B8A, 3, "sum")
    
  • min: Minimum of all valid pixels in the window
    e.g.,  --> wnd(B2, 3, "min")
    
  • max: Maximum of all valid pixels in the window
    e.g.,  --> wnd(B2, 7, "max")
    
  • mean: Mean of all valid pixels in the window
    e.g.,  --> wnd(B2, 7, "mean")
    
  • median: Median of all valid pixels in the window
    e.g.,  --> wnd(B3, 5, "median")
    
  The function can be selected from the drop-down list:
  
  
  
• Statistical Raster Properties
  Provides statistical properties of a raster. Optionally it can be specified if accurate statistics shall be computed. By default, the accurate calculation is disabled and only sub-sampled raster will be used to compute the statistical properties. If set to true all samples of the raster are considered. If statistics have already been computed, then these are used and not recomputed. Except, these have a low accuracy and accurate results are requested.
  Please note, that computing the statistics can be time consuming, especially when requesting accurate results.
  The functions are used as follows: stx(<band_name>, "<property>", accurate)
  The following functions are available:
  
  • min: Minimum value of the raster
    e.g.,  --> stx(B2, "min")
    
  • max: Maximum value of the raster
    e.g.,  --> stx(B2, "max", true)
    
  • mean: Mean value of the raster
    e.g.,  --> stx(B2, "mean", false)
    
  • median: Median value of the raster
    e.g.,  --> stx(B3, "median")
    
  • sigma: Standard deviation value of the raster
    e.g.,  --> stx(B3, "sigma", true)
    
  • rsd: Coefficient of variation or relative standard deviation (RSD) value of the raster
    e.g.,  --> stx(B3, "rsd", false)
    
  • enl: Equivalent number of looks (ENL) value of the raster
    e.g.,  --> stx(B3, "enl")