i.points.auto

Generate ground control points for image group to be rectified.

i.points.auto [-c] group=name source_image=name target_image=name [order=integer] npoints=integer [detail=string] [threshold=float] [--verbose] [--quiet] [--qq] [--ui]

Example:

i.points.auto group=name source_image=name target_image=name npoints=integer

grass.script.run_command("i.points.auto", group, source_image, target_image, order=1, npoints, detail="fine", threshold=0.0, flags=None, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("i.points.auto", group="name", source_image="name", target_image="name", npoints=integer)

Parameters

Command linePython (grass.script)

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)
    Allowed values: 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.
    Allowed values: coarse, medium, fine
    Default: fine
threshold=float
    RMS error threshold. Recommended: source image resolution or smaller
    Default: 0.0
-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
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

group : str, required
    Name of input imagery group
    Used as: input, group, name
source_image : str, required
    Name of input raster map
    Used as: input, raster, name
target_image : str, required
    Name of input raster map
    Used as: input, raster, name
order : int, optional
    Transformation polynom order (1-3)
    Allowed values: 1, 2, 3
    Default: 1
npoints : int, required
    Maximum number of points to generate
detail : str, optional
    How detailed should the information be to be used.
    Allowed values: coarse, medium, fine
    Default: fine
threshold : float, optional
    RMS error threshold. Recommended: source image resolution or smaller
    Default: 0.0
flags : str, optional
    Allowed values: c
    c
        Use current region settings in source location instead of source map extends
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

DESCRIPTION

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).

NOTES

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.

REFERENCE

(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)

AUTHORS

Ivan Michelazzi
Luca Miori
Markus Metz

SOURCE CODE

Available at: i.points.auto source code (history)
Latest change: Friday Feb 21 10:10:05 2025 in commit 7d78fe3