Image processing

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Revision as of 10:53, 25 February 2008 by Neteler (talk | contribs) (+LAS format)
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This page needs review and enhancement from an expert! Thanks!

Screenshots

Georectification

  • Tcl/Tk georectification tool is available from the File menu in the GUI.
  • i.points, i.vpoints
  • i.ortho.photo

A multi-band image may be grouped and georectified with a single set of ground control points. (i.group, i.target, i.rectify)

Clustering

  • Where's that table describing this? From the GRASS book help??
MN: yes
  • i.class, i.cluster

Filtering

  • i.fft, i.ifft, i.pca, r.mfilter, r.neighbors

Enhancement

  • i.landsat.rgb
  • i.fusion.brovey
  • i.oif


Ideas collection for improving GRASS' Image processing capabilities

Below modules need some tuning before being added to GRASS 6. Volunteers welcome.

Spectral unmixing

Spectral angle mapping

Geocoding

  • i.points.auto: automated search of GCPs based on FFT correlation (as improved i.points)
  • i.homography: geocoding with lines (instead of points) with homography (as improved i.points; it was formerly called i.linespoints)
  • support splines from GDAL (see GRASS_AddOns#Imagery_add-ons)

Image classification

Stereo

This is stand-alone stereo modeling software (DEM extraction etc). Waits for integration into GRASS.

Lidar LAS format

LAS Tools by M. Isenburg: http://www.cs.unc.edu/~isenburg/lastools/

   las2txt | r.in.xyz in=- fs=

Improving the existing code

It might be sensible to merge the various image libraries:

  • GRASS 6 standard libs:
    • lib/imagery/: standard lib, in use (i.* except for i.points3, i.rectify3)
    • imagery/i.ortho.photo/libes/: standard lib, in use (i.ortho.photo, photo.*)
  • GRASS 5 (! only) image3 lib:
    • lib/image3/: never finished improvement which integrated the standard lib and the ortho lib. Seems to provide also ortho rectification for satellite data (i.points3, i.rectify3)
  • GRASS 5/6 image proc commands:
    • merge of i.points, i.vpoints, i.points3
    • merge of i.rectify and i.rectify3
    • addition of new resampling algorithms such as bilinear, cubic convolution (take from r.proj or upcoming r.resamp.aggreg)
    • add other warping methods (maybe thin splines from GDAL?)
    • implement/finish linewise ortho-rectification of satellite data