align_metrology_model — Alignment of a metrology model.
align_metrology_model( : : MetrologyHandle, Row, Column, Angle : )
align_metrology_model moves and rotates the whole metrology model
MetrologyHandle
relative to the image coordinate system which has its origin in the
top left corner.
For an explanation of the concept of 2D metrology see the introduction of chapter 2D Metrology.
An alignment ensures, that the position and
orientation of the metrology model is adapted to the
objects to be measured in the current image. The alignment is then
used by apply_metrology_model to perform the measurement.
First the metrology model is rotated by Angle, then
the metrology model is translated by Row and Column.
The values of the alignment are overwritten by the
next call of align_metrology_model.
The parameters of the alignment can be determined using diverse methods. Here, three possibilities to determine the parameters are listed:
If the metrology model can be extracted using region processing and if the
pose of the Region changes only slightly in subsequent images, the
parameters of the reference system of the metrology model and of the
alignment can be derived using region analysis. In the following picture
threshold and smallest_rectangle2 were used to obtain
these parameter.
threshold is shown in red.
The rectangle computed with smallest_rectangle2 is shown in green.
Setting the reference system
In the image in which the metrology model was defined, extract a region
containing the metrology objects. The pose of this region with
respect to the image coordinate system is determined and set
as the reference system of the metrology model using
set_metrology_model_param.
This step is only performed once when setting up the metrology model.
Example:
threshold(Image, Region, 0, 50)
smallest_rectangle2(Region, RowOrig, ColumnOrig, AngleOrig,
Length1, Length2)
set_metrology_model_param(MetrologyHandle, 'reference_system',
[RowOrig, ColumnOrig, AngleOrig])
Determining the alignment
In an image where the metrology model occurs in a different Pose, the current pose if the extracted region is determined. This pose is then used to align the metrology model.
Example:
threshold(CurrentImage, Region, 0, 50)
smallest_rectangle2(Region, RowAlign, ColumnAlign, AngleAlign,
Length1, Length2)
align_metrology_model(MetrologyHandle, RowAlign, ColumnAlign,
AngleAlign)
If a shape model is used to align the metrology model,
the reference system with respect to which the metrology objects are given
has to be set so that it coincides with the coordinate system used by the
shape model. Only then, the results
('row', 'column', 'angle') of
get_generic_shape_model_result can be used directly in
align_metrology_model to align the metrology model in the current
image. The individual steps that are needed, are shown below.
| ( 1) | ( 2) | ( 3) |
Setting the reference system
In the image in which the metrology model was defined, the pose of the
origin of the shape model is determined and set
as the reference system of the metrology model using
set_metrology_model_param. This step is only performed once
when setting up the metrology model.
Example:
train_generic_shape_model(Image, ModelID)
area_center(Image, Area, RowOrig, ColumnOrig)
set_metrology_model_param(MetrologyHandle, 'reference_system',
[RowOrig,ColumnOrig,0])
Determining the alignment
In an image, in which the object to be measured occurs in a different
pose, the current pose of the shape model is determined and set
in the metrology model using align_metrology_model.
Example:
find_generic_shape_model(CurrentImage, ModelID, MatchResultID,
NumMatchResult)
get_generic_shape_model_result(MatchResultID, 'all', 'row',
RowAlign)
get_generic_shape_model_result(MatchResultID, 'all', 'column',
ColumnAlign)
get_generic_shape_model_result(MatchResultID, 'all', 'angle',
AngleAlign)
align_metrology_model(MetrologyHandle, RowAlign, ColumnAlign,
AngleAlign)
If certain model points (given as [PRowModel], [PColumnModel]) can be clearly identified and if they can still be clearly identified in further images in which the objects to be measured can occur shifted or rotated, a rigid transformation can be calculated between those points. The transformation parameters can then directly be used for aligning the model. In this case, the reference point of the metrology model does not have to be changed.
| ( 1) | ( 2) |
Determine the point correspondences
Estimate the model pose
The following operator sequence calculates the parameters of the model
pose
(Row, Column, Angle)
from corresponding points in the model image and one other image.
Example:
vector_to_rigid(PRowModel, PColumnModel, PRowCurrent,
PColumnCurrent, HomMat2D)
hom_mat2d_to_affine_par(HomMat2D, Sx, Sy, Angle, Theta,
Row, Column)
align_metrology_model(MetrologyHandle, Row, Column, Angle)
This operator modifies the state of the following input parameter:
During execution of this operator, access to the value of this parameter must be synchronized if it is used across multiple threads.
MetrologyHandle (input_control, state is modified) metrology_model → (handle)
Handle of the metrology model.
Row (input_control) real → (real / integer)
Row coordinate of the alignment.
Default: 0
Column (input_control) real → (real / integer)
Column coordinate of the alignment.
Default: 0
Angle (input_control) angle.rad → (real / integer)
Rotation angle of the alignment.
Default: 0
read_image (Image, 'metal-parts/circle_plate_01')
create_metrology_model (MetrologyHandle)
get_image_size (Image, Width, Height)
set_metrology_model_image_size (MetrologyHandle, Width, Height)
CircleParam := [354,274,53]
CircleParam := [CircleParam,350,519,53]
add_metrology_object_generic (MetrologyHandle, 'circle', CircleParam, 20,\
5, 1, 30, [], [], CircleIndices)
create_generic_shape_model (ModelID)
set_generic_shape_model_param (ModelID, 'metric', 'use_polarity')
set_generic_shape_model_param (ModelID, 'min_contrast', 20)
train_generic_shape_model (Image, ModelID)
* Determine location of shape model origin
area_center (Image, Area, RowOrigin, ColOrigin)
set_metrology_model_param (MetrologyHandle, 'reference_system', \
[RowOrigin,ColOrigin,0])
read_image (CurrentImage, 'metal-parts/circle_plate_02')
find_generic_shape_model (CurrentImage, ModelID, MatchResultID, \
NumMatchResult)
get_generic_shape_model_result (MatchResultID, 'all', 'row', Row)
get_generic_shape_model_result (MatchResultID, 'all', 'column', Col)
get_generic_shape_model_result (MatchResultID, 'all', 'angle', Angle)
align_metrology_model (MetrologyHandle, Row, Col, Angle)
apply_metrology_model (CurrentImage, MetrologyHandle)
get_metrology_object_result (MetrologyHandle, CircleIndices, 'all', \
'result_type', 'all_param', Rectangle)
get_metrology_object_result_contour (Contour, MetrologyHandle, \
CircleIndices, 'all', 1.5)
If the parameters are valid, the operator
align_metrology_model returns the value 2 (
H_MSG_TRUE)
.
If necessary, an exception is raised.
set_metrology_model_param,
add_metrology_object_generic
get_metrology_object_model_contour
2D Metrology