Requests for Comments-7: Better support of no data in Orfeo ToolBox

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Status

  • Submitted by Julien Michel (01/09/2015 17:25)
  • Votes pending

Content

What changes will be made and why they will make a better Orfeo ToolBox

Currently, Orfeo ToolBox does not read, write and handle the no_data flags reported by gdal from various format (geotiff being the most obvious one). Some filters support setting this value by hand. This RFC has several components to improve this situation:

  • Read the no data flags if present, store them in the metadata dictionnary of the Image/VectorImage and write them back if possible
  • Also make NaN values to be considered as no data
  • Write filter an application that can build a no data mask from an image
  • Write filter and application that can switch the no-data value of an image
  • Support no data flag export in meta-data dictionnary fo filter producing no data values (resampling filters for instance)
  • Support no data flag in filters for which no data can affect the result (such as statistical estimation)

Open issues (no intended to be solved in this RFC):

  • No data flag handling in interpolators
  • Solution for general support of no data in all filters (may be out of reach for now)
When will those changes be available (target release or date)

These changes will be available for next release (OTB 5.2) I did some of the code, and the CS team under CNES contract is currently working on improving it. See feature branch: https://git.orfeo-toolbox.org/otb.git/shortlog/refs/heads/no_data_app