i.cca(1)

📦
version 8.4.2 · 8 versions
, in fedora 44

💖 i.cca — the GRASS GIS User's Manual, but make it make sense 💖

okay bestie, sit down, hydrate, because we're doing canonical components analysis today and honestly? it's giving main character energy. this is the page for i.cca(1) from the GRASS GIS User's Manual, and by the end of this you're gonna understand it better than the people who wrote it. no cap. 🫶

🌸 NAME 🌸

i.cca — the Canonical components analysis (CCA) program for image processing. that's it, that's the vibe. 💅

🎀 KEYWORDS 🎀

imagery, statistics, CCA, canonical components analysis

iykyk. 🔥

✨ SYNOPSIS ✨

here's how you actually summon her:

i.cca
i.cca --help
i.cca group=name subgroup=name signature=name output=name  [--overwrite]
[--help]  [--verbose]  [--quiet]  [--ui]

🦋 Flags 🦋

  • --overwrite — lets your output files just... overwrite existing files. bold. slay. 💀
  • --help — prints the usage summary so you're not out here guessing. 🧚
  • --verbose — verbose module output, aka she tells you EVERYTHING. 😭
  • --quiet — quiet module output. the introvert setting. 🤫
  • --ui — forces the GUI dialog to launch. for the visual girlies. 🌈

🍓 Parameters 🍓

  • group=name [required] — name of the input imagery group. you NEED this, bestie.
  • subgroup=name [required] — name of the input imagery subgroup. also required, don't skip her.
  • signature=name [required] — the file containing spectral signatures. required!
  • output=name [required] — output raster map prefix name. required. yes, again. 👑

💜 DESCRIPTION 💜

so i.cca is an image processing program, and what she does is genuinely iconic: she takes any number of (raster) band files plus a signature file, and spits out the same number of raster band files — except transformed so the categories indicated by the signatures have maximum separability. the way that works?? it's the whole point. 🔥

this implementation of the canonical components transformation is based on the algorithm contained in the LAS image processing system. and plot twist: CCA is also known as the "Canonical components transformation". two names, one queen. 👑

typically you'd use the g.gui.iclass program to collect a set of signatures, and then pass those signatures along with the raster band files to i.cca. the raster band file names get specified on the command line by giving the group and subgroup that were used to collect the signatures. simple, clean, effective. ✨

the output raster map names are built by appending a ".1", ".2", etc. to the output raster map name you specified on the command line. she's a naming-convention girlie. 🎀

🌸 Parameters (the detailed version) 🌸

  • group=name — name of the imagery group to which the raster band files used belong.
  • subgroup=name — name of the imagery subgroup to which the raster band files used belong.
  • signature=name — name of an ASCII file containing spectral signatures.
  • output=name — output raster map prefix name. the output raster map layer names are built by appending a ".1", ".2", etc. onto the output name specified by the user. so if you name it mything, bestie, you're getting mything.1, mything.2, and so on. 💅

📝 NOTES 📝

i.cca respects the current geographic region definition and the current mask setting while performing the transformation. she's respectful. she reads the room. 🫶

📚 REFERENCES 📚

Schowengerdt, Robert A. Techniques for Image Processing and Classification in Remote Sensing, Academic Press, 1983.

(the academic source material. we love a citation moment. 🎓)

👀 SEE ALSO 👀

g.gui.iclass, i.gensig, i.cluster, i.pca, r.covar, r.mapcalc

the whole friend group. go say hi. 🦋

👑 AUTHORS 👑

  • David Satnik, GIS Laboratory, Central Washington University
  • Ali R. Vali, University of Texas
  • Semantic label support: Maris Nartiss, University of Latvia

legends, honestly. 💖

💻 SOURCE CODE 💻

Available at: i.cca source code (history)

Accessed: Saturday Jan 17 05:41:39 2026

Main index | Imagery index | Topics index | Keywords index | Graphical index | Full index

© 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual

and that's the whole page, bestie!! 🎉 this was GRASS GIS 8.4.2, manual page i.cca(1), accessed Saturday Jan 17 05:41:39 2026, brought to you by the © 2003-2025 GRASS Development Team. go transform some bands. periodt. 💅✨🫶

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