Operator Reference
contour_to_world_plane_xld (Operator)
contour_to_world_plane_xld — Transform an XLD contour into the plane z=0 of a world coordinate system.
Signature
contour_to_world_plane_xld(Contours : ContoursTrans : CameraParam, WorldPose, Scale : )
Description
The operator contour_to_world_plane_xld transforms contour points
given in Contours into the plane z=0 in a world coordinate system
and returns the 3D contour points in ContoursTrans. The world
coordinate system is chosen by passing its 3D pose relative to the camera
coordinate system in WorldPose.
Hence, latter one is expected in the form
, where
ccs denotes the camera coordinate system and
wcs the world coordinate system
(see Transformations / Poses
and “Solution Guide III-C - 3D Vision”).
In CameraParam you must pass the internal camera parameters
(see Calibration for the sequence of the parameters and
the underlying camera model).
In many cases CameraParam and WorldPose are the result of
calibrating the camera with the operator calibrate_cameras. See
below for an example.
With the parameter Scale you can scale the resulting 3D
coordinates.
The parameter Scale must be specified as the ratio desired
unit/original unit. The original unit is determined by the coordinates of
the calibration object. If the original unit is meters (which is the case if
you use the standard calibration plate), you can set the desired unit
directly by selecting 'm', 'cm', 'mm' or
'um' for the parameter Scale.
Internally, the operator first computes the line of sight between the
projection center and the image point in the camera coordinate system,
taking into account the radial distortions.
The line of sight is then transformed
into the world coordinate system specified in WorldPose. By
intersecting the plane z=0 with the line of sight the 3D coordinates of the
transformed contour ContoursTrans are obtained.
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
Contours (input_object) xld_cont(-array) → object
Input XLD contours to be transformed in image coordinates.
ContoursTrans (output_object) xld_cont(-array) → object
Transformed XLD contours in world coordinates.
CameraParam (input_control) number-array → (real / integer / string)
Internal camera parameters.
WorldPose (input_control) pose → (real / integer)
3D pose of the world coordinate system in camera coordinates.
Number of elements: 7
Scale (input_control) number → (string / integer / real)
Scale or dimension
Default: 'm'
Suggested values: 'm', 'cm', 'mm', 'microns', 'um', 1.0, 0.01, 0.001, 1.0e-6, 0.0254, 0.3048, 0.9144
Restriction:
Scale > 0
Example (HDevelop)
* Perform camera calibration (with standard calibration plate).
calibrate_cameras (CalibDataID, Error)
get_calib_data (CalibDataID, 'camera', 0, 'params', CamParam)
* Get reference pose (pose 2 of calibration object 0).
get_calib_data (CalibDataID, 'calib_obj_pose', [0,2], 'pose', WorldPose)
* Compensate thickness of plate.
set_origin_pose(ObjInCameraPose, 0, 0, 0.0006, WorldPose)
* Transform contours into world coordinate system (unit mm).
contour_to_world_plane_xld(Contours, ContoursTrans, CamParam, \
WorldPose, 'mm')
Result
contour_to_world_plane_xld returns 2 (
H_MSG_TRUE)
if all parameter values
are correct. If necessary, an exception is raised.
Possible Predecessors
create_pose,
hom_mat3d_to_pose,
camera_calibration,
hand_eye_calibration,
set_origin_pose
See also
Module
Calibration