NAME
i.points.auto - Generate ground control points for image group to be rectified.
KEYWORDS
imagery,
ground control points
SYNOPSIS
i.points.auto
i.points.auto --help
i.points.auto [-c] group=name source_image=name target_image=name [order=integer] npoints=integer [detail=string] [threshold=float] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -c
- Use current region settings in source location instead of source map extends
- --help
- Print usage summary
- --verbose
- Verbose module output
- --quiet
- Quiet module output
- --ui
- Force launching GUI dialog
Parameters:
- group=name [required]
- Name of input imagery group
- source_image=name [required]
- Name of input raster map
- target_image=name [required]
- Name of input raster map
- order=integer
- Transformation polynom order (1-3)
- Options: 1, 2, 3
- Default: 1
- npoints=integer [required]
- Maximum number of points to generate
- detail=string
- How detailed should the information be to be used.
- Options: coarse, medium, fine
- Default: fine
- threshold=float
- RMS error threshold. Recommended: source image resolution or smaller
- Default: 0.0
i.points.auto tries to automatically generate a given number
of new ground control points (GCPs) by matching the input map to a target
map through FFT correlation, based on a few existing ground control points,
previously defined by the user, for example through the
Ground Control Points Manager.
The goal of the module is thus to automaticallty increase the number of control
points to enable higher quality geocoding of imagery to a master image
(co-registration).
It is recommended to use maps filtered with the DIVERSITY or STDDEV filters
of the
r.neighbors module, with a window size of 3x3 or 5x5
pixels. However, the algorithm sometimes works well also with the
original maps. The produced GCPs can then be used on the original imagery.
The actual number of newly generated ground control points will likely
be less than the given maximum number of ground control points because
each generated point is filtered using its FFT correlation
coefficient, and optionally also by the given RMS threshold.
i.points.auto supports the usual transformation orders 1-3 and
requires the corresponding number of previously set ground control
points: 3 for order 1, 6 for order 2, 10 for order 3.
The GRASS 4
Image
Processing manual
i.group,
i.rectify,
i.target,
r.neighbors,
Ground Control Points Manager
(note that the former module name was
i.coregister)
- Neteler, M, D. Grasso, I. Michelazzi, L. Miori, S. Merler, and C.
Furlanello (2005). An integrated toolbox for image registration, fusion and
classification. International Journal of Geoinformatics, 1(1):51-61
(PDF)
Ivan Michelazzi
Luca Miori
Markus Metz
SOURCE CODE
Available at:
i.points.auto source code
(history)
Latest change: Thursday Aug 15 15:27:16 2024 in commit: a0e37beaf0ce8a4cc6ec615b6d3d40e39f9d725f
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© 2003-2024
GRASS Development Team,
GRASS GIS 8.4.1dev Reference Manual