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Remapping data

When extracting the data (in binary or image format), Naiad system offers the ability to remap the data over a user-defined grid, in whatever area, projection and resolution. This tutorial describes the different step for remapping the data in the extraction process.

 Defining an output grid

The remapping is managed within the extraction wizard through the Mapping tab. To activate the remapping function, the Remap data toggle should be checked. The following steps will be to define the grid, meaning :

  • projection
  • limits
  • resolution

Projection

The Projection list box allows to select the projection of your choice for your grid within a predefined set of projections, either provided by default by Naiad or defined previously by the user. It is indeed possible for the user to extend this list by adding its own projections. Defining a new projection is performed by clicking on Add projection button.

Remapping-available-projectionsSelection of available projections

A new projection is defined using its WKT string representation, which is the OGC (Open Geospatial Consortium) standard to express projection in human readable way. Examples of WKT strings for a large number of projection can be found on http://spatialreference.org/ : these examples can be copy/pasted into the Description text field of the projection definition window. The Name field is the name by which the new projection will appear in the projection list box.

Remapping-Adding-a-new-projectionDefining and adding a new projection

Grid specification

Once a projection has been defined and/or selected, the output grid must be specified. This consists in :

  • entering the coordinates of the upper left and bottom right corners of the grid within the selected projection, if these coordinates are different from the data selection area defined on the main map or through the Area tab. For non-cylindrical projections, the grid corners and the corners of the data selection area will differ and have to be defined separetely : the user should ensure that the selection area includes the grid area.
  • defining the dimensions of the grid, by entering the grid horizontal and vertical resolution (available for regular cylindrical projections only, by selecting Resolution option) or the number of lines and columns (selecting the Dimension option).
Remapping-Defining-the-grid-specification Defining the grid specification