Operator Reference
gen_radial_distortion_map (Operator)
gen_radial_distortion_map — Generate a projection map that describes the mapping of images corresponding
to a changing radial distortion.
Signature
gen_radial_distortion_map( : Map : CamParamIn, CamParamOut, MapType : )
Description
gen_radial_distortion_map computes the mapping of images
corresponding to a changing radial distortion in accordance to the internal
camera parameters CamParamIn and CamParamOut which can be
obtained, e.g., using the operator calibrate_cameras.
CamParamIn and CamParamOut contain the old and the new
camera parameters including the old and the new radial distortion,
respectively (also see Calibration for the sequence of
the parameters and the underlying camera model). Each pixel of the
potential output image is transformed into the image plane using
CamParamOut and subsequently projected into a subpixel position
of the potential input image using CamParamIn. Note that
gen_radial_distortion_map can only be used with area scan cameras.
The mapping function is stored in the output image Map. The size of
Map is given by the camera parameters CamParamOut and
therefore defines the size of the resulting mapped images using
map_image. The size of the images to be mapped with map_image
is determined by the camera parameters CamParamIn.
MapType is used to specify the type of the output Map.
If 'nearest_neighbor' is chosen, Map consists of one image
containing one channel, in which for each pixel of the resulting image the
linearized coordinate of the pixel of the input image is stored that is the
nearest neighbor to the transformed coordinates. If 'bilinear'
interpolation is chosen, Map consists of one image containing five
channels. In the first channel for each pixel in the resulting image the
linearized coordinates of the pixel in the input image is stored that is in
the upper left position relative to the transformed coordinates.
The four other channels contain the weights of the four neighboring pixels
of the transformed coordinates which are used for the bilinear interpolation,
in the following order:
| 2 | 3 |
| 4 | 5 |
The second channel, for example, contains the weights of the pixels that
lie to the upper left relative to the transformed coordinates.
If 'coord_map_sub_pix' is chosen, Map consists of
one vector field image of the semantic type 'vector_field_absolute', in
which for each pixel of the resulting image the subpixel precise
coordinates in the input image are stored.
If CamParamOut was computed via
change_radial_distortion_cam_par, the mapping describes the effect
of a lens with a modified radial distortion . If
, the mapping corresponds to a rectification.
A subsequent pose estimation (determination of the
external camera parameters) is not affected by this operation.
If several images have to be mapped using the same camera parameters,
gen_radial_distortion_map in combination with
map_image is much more efficient than the operator
change_radial_distortion_image because the transformation
must be computed only once.
If you want to re-use the created map in another program, you can save it as
a multi-channel image with the operator write_image, using the format
'tiff'.
Execution Information
- Multithreading type: reentrant (runs in parallel with non-exclusive operators).
- Multithreading scope: global (may be called from any thread).
- Processed without parallelization.
Parameters
Map (output_object) (multichannel-)image → object (int4 / int8 / uint2 / vector_field)
Image containing the mapping data.
CamParamIn (input_control) campar → (real / integer / string)
Old camera parameters.
CamParamOut (input_control) campar → (real / integer / string)
New camera parameters.
MapType (input_control) string → (string)
Type of the mapping.
Default: 'bilinear'
List of values: 'bilinear', 'coord_map_sub_pix', 'nearest_neighbor'
Result
gen_radial_distortion_map returns 2 (
H_MSG_TRUE)
if all parameter values
are correct. If necessary, an exception is raised.
Possible Predecessors
change_radial_distortion_cam_par,
camera_calibration,
hand_eye_calibration
Possible Successors
Alternatives
change_radial_distortion_image
See also
change_radial_distortion_contours_xld
Module
Calibration