i.ortho.rectify(1grass) GRASS GIS User's Manual i.ortho.rectify(1grass)
NAME
i.ortho.rectify - Orthorectifies an image by using the image to photo
coordinate transformation matrix.
KEYWORDS
imagery, orthorectify
SYNOPSIS
i.ortho.rectify
i.ortho.rectify --help
i.ortho.rectify [-cap] group=name [input=name[,name,...]] exten-
sion=string [resolution=float] [memory=memory in MB]
[method=string] [angle=name] [--overwrite] [--help] [--verbose]
[--quiet] [--ui]
Flags:
-c
Use current region settings in target location (def.=calculate
smallest area)
-a
Rectify all raster maps in group
-p
Enable panorama camera correction
--overwrite
Allow output files to overwrite existing files
--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
input=name[,name,...]
Name of input raster map(s)
extension=string [required]
Output raster map(s) suffix
resolution=float
Target resolution (ignored if -c flag used)
memory=memory in MB
Maximum memory to be used (in MB)
Cache size for raster rows
Default: 300
method=string
Interpolation method to use
Options: nearest, linear, cubic, lanczos, linear_f, cubic_f, lanc-
zos_f
Default: nearest
angle=name
Raster map with camera angle relative to ground surface
DESCRIPTION
i.photo.rectify rectifies an image by using the image to photo coordi-
nate transformation matrix created by i.photo.2image and the rectifica-
tion parameters created by i.photo.2target. Rectification is the
process by which the geometry of an image is made planimetric. This is
accomplished by mapping an image from one coordinate system to another.
In i.photo.rectify the parameters computed by i.photo.2image and
i.photo.2target are used in equations to convert x,y image coordinates
to standard map coordinates for each pixel in the image. The result is
an image with a standard map coordinate system, compensated for relief
distortions and photographic tilt. Upon completion of the program the
rectified image is deposited in a previously targeted GRASS LOCATION.
Images can be resampled with various different interpolation methods:
nearest neighbor assignment, bilinear and bicubic interpolation. The
bilinear and bicubic interpolation methods are also available with a
fallback option. These methods "fall back" to simpler interpolation
methods along NULL borders. That is, from bicubic to bilinear to near-
est.
The process may take an hour or more depending on the size of the im-
age, the speed of the computer, the number files, and the size and res-
olution of the selected window.
The rectified image will be located in the target LOCATION when the
program is completed. The original unrectified files are not modified
or removed.
The optional angle output holds the camera angle in degrees to the lo-
cal surface, considering local slope and aspect. A value of 90 degrees
indicates that the camera angle was orthogonal to the local surface, a
value of 0 degrees indicates that the camera angle was parallel to the
local surface and negative values indicate that the surface was invisi-
ble to the camera. As a rule of thumb, values below 30 degrees indicate
problem areas where the orthorectified output will appear blurred. Be-
cause terrain shadowing effects are not considered, areas with high
camera angles may also appear blurred if they are located (viewed from
the camera position) behind mountain ridges or peaks.
i.photo.rectify can be run directly, specifying options in the command
line or the GUI, or it can be invoked as OPTION 8 through i.or-
tho.photo. If invoked though i.ortho.photo, an interactive terminal is
used to determine the options.
Interactive mode
You are first asked if all images within the imagery group should be
rectified. If this option is not chosen, you are asked to specify for
each image within the imagery group whether it should be rectified or
not.
More than one file may be rectified at a time. Each file should have a
unique output file name. The next prompt asks you for an extension to
be appended to the rectified images.
The next prompt will ask you whether a camera angle map should be pro-
duced and if yes, what should be its name.
After that you are asked if overwriting existing maps in the target lo-
cation and mapset should be allowed.
The next prompt asks you to select one of two windows:
Please select one of the following options
1. Use the current window in the target location
2. Determine the smallest window which covers the image
>
If you choose option 2, you can also specify a desired target resolu-
tion.
i.photo.rectify will only rectify that portion of the image that occurs
within the chosen window. Only that portion will be relocated in the
target database. It is therefore important to check the current window
in the target LOCATION if choice number one is selected.
Next you are asked to select an interpolation method.
Please select one of the following interpolation methods
1. nearest neighbor
2. bilinear
3. bicubic
4. bilinear with fallback
5. bicubic with fallback
>
The last prompt will ask you about the amount of memory to be used by
i.photo.rectify.
SEE ALSO
i.ortho.photo
i.ortho.camera
i.photo.2image
i.photo.2target
i.ortho.init
i.rectify
AUTHOR
Mike Baba, DBA Systems, Inc.
Updated rectification and elevation map to FP 1/2002 Markus Neteler
Bugfixes and enhancements 12/2010 Markus Metz
SOURCE CODE
Available at: i.ortho.rectify source code (history)
Accessed: unknown
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GRASS 7.8.7 i.ortho.rectify(1grass)
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