Operator Reference
set_metrology_object_param (Operator)
set_metrology_object_param — Set parameters for the metrology objects of a metrology model.
Signature
set_metrology_object_param( : : MetrologyHandle, Index, GenParamName, GenParamValue : )
Description
set_metrology_object_param is used to set or change the
different parameters of a metrology object.
For an explanation of the concept of 2D metrology see the introduction of chapter 2D Metrology.
The metrology model is defined by the handle
MetrologyHandle. The parameter Index specifies
the metrology objects for which the parameters are set. The parameters
of all metrology objects are set if the parameter Index is
set to 'all'. All parameters can also
be set when creating a metrology object with
add_metrology_object_generic,
add_metrology_object_circle_measure,
add_metrology_object_ellipse_measure,
add_metrology_object_line_measure, or
add_metrology_object_rectangle2_measure.
The current configuration of the metrology model can be accessed
with get_metrology_object_param. All parameters that can be
set with set_metrology_object_param can be reset with
reset_metrology_object_param.
In the following all generic parameters with the default values
are listed. But note that
for a lot of applications the default values are sufficient and
no adjustment is necessary. The following values for
GenParamName and GenParamValue are possible -
ordered by different categories:
Creating measure regions:
- 'measure_length1':
-
The value of this parameter specifies the half length of the measure regions perpendicular to the metrology object boundary. It is equivalent to the measure tolerance. The unit of this value is pixel.
Suggested values: 10.0, 20.0, 30.0
Default: 20.0
Restriction: 'measure_length1' >= 1.0
- 'measure_length2':
-
The value of this parameter specifies the half length of the measure regions tangential to the metrology object boundary. The unit of this value is pixel.
Suggested values: 3.0, 5.0, 10.0
Default: 5.0
Restriction: 'measure_length2' >= 0.0
- 'measure_distance':
-
The value of this parameter specifies the desired distance between the centers of two measure regions. If the value leads to too few measure regions, the parameter has no influence and the number of measure regions will be increased to the minimum required number of measure regions (circle = 3, ellipse = 5, line = 2, rectangle = 2 per side = 8). The unit of this value is pixel.
If this value is set, the parameter 'num_measures' has no influence.
Suggested values: 5.0, 15.0, 20.0, 30.0
Default: 10.0
- 'num_measures':
-
The value of this parameter specifies the desired number of measure regions.
The minimum number of measure regions depends on the type of the metrology object:
-
Line: 2 measure regions
-
Circle: 3 measure regions
-
Circular arc: 4 measure regions
-
Ellipse: 5 measure regions
-
Elliptic arc: 6 measure regions
-
Rectangle: 8 measure regions (2 regions each side)
If the chosen value is too low, 'num_measures' is automatically set to the respective minimum value.
If this value is set, the parameter 'measure_distance' has no influence.
Suggested values: 8, 10, 16, 20, 30, 50, 100
-
Edge detection:
- 'measure_sigma':
-
The parameter specifies the sigma for the Gaussian smoothing. The meaning, the use, and the default value of this parameter are described with the operator
measure_posby the parameterSigma. - 'measure_threshold':
-
The parameter specifies the minimum edge amplitude. The meaning, the use, and the default value of this parameter are described with the operator
measure_posby the parameterThreshold. - 'measure_select':
-
The parameter specifies the selection of end points of the edges. The meaning, the use, and the default value of this parameter are described with the operator
measure_posby the parameterSelect. - 'measure_transition':
-
The parameter specifies the use of dark/light or light/dark edges. The meaning and the use of the values 'all', 'positive', and 'negative' for the parameter 'measure_transition' is described with the operator
measure_posby the parameterTransition. Additionally, 'measure_transition' can be set to the value 'uniform'. Then, all positive edges (dark/light edges) and all negative edges (light/dark edges) are detected by the edge detection but when fitting the geometric shapes, the edges with different edge types are used separately, i.e., for each instance of a geometric shape either only the positive edges or the negative edges are used.The measure direction within the measure regions is from the inside to the outside of the metrology object for objects of the types circle, ellipse, or rectangle. For metrology objects of the type line measure direction within the measure regions is from the left to the right, seen from the first point of the line (see
RowBeginandColumnBeginof the operatoradd_metrology_object_line_measure).List of values: 'all', 'negative', 'positive', 'uniform'
Default: 'all'
- 'measure_interpolation':
The parameter specifies the type of interpolation to be used. The meaning, the use and the default value of this parameter is described with the operator
gen_measure_rectangle2by the parameterInterpolation.
Fitting the geometric shapes:
- 'min_score':
-
The parameter determines what score a potential instance must at least have to be regarded as a valid instance of the metrology object. The score is the number of detected edges that are used to compute the results divided by the maximum number of measure regions (see
apply_metrology_model). If it can be expected that all edges of the metrology object are present, the parameter 'min_score' can be set to a value as high as 0.8 or even 0.9. Note that in images with a high degree of clutter or strong background texture the parameter 'min_score' should be set to a value not much lower than 0.7 since otherwise false instances of a metrology object could be found.Suggested values: 0.5, 0.7, 0.9
Default: 0.7
- 'num_instances':
-
The parameter specifies the maximum number of successfully fitted instances of each metrology object after which the fitting will stop (see
apply_metrology_model). Successfully fitted instances of the metrology objects must have a score of at least the value of 'min_score'.Suggested values: 1, 2, 3, 4
Default: 1
- 'distance_threshold':
-
apply_metrology_modeluses a randomized search algorithm (RANSAC) to fit the geometric shapes. An edge point is considered to be part of a fitted geometric shape, if the distance of the edge point to the geometric shape does not exceed the value of 'distance_threshold'.Suggested values: 0, 1.0, 2.0, 3.5, 5.0
Default: 3.5
- 'max_num_iterations':
-
The RANSAC algorithm estimates the number of iterations necessary for fitting the requested geometric shape. The estimation is based on the extracted edge data and the complexity of the shape. When setting the value of the parameter 'max_num_iterations', an upper limit for the computed number of iterations is defined. The number of iterations is still estimated by the RANSAC algorithm but cannot exceed the value of 'max_num_iterations'. Setting this parameter can be helpful, if the quality of the fitting is not as important as observing time limits. However, if 'max_num_iterations' is set too low, the algorithm will return low-quality or no results.
By default, 'max_num_iterations' is set to -1, indicating that no additional upper limit is set for the number of iterations of the RANSAC algorithm.
Suggested values: 10, 100, 1000
Default: -1
- 'rand_seed':
-
The parameter specifies the seed for the random number generator for the RANSAC algorithm that is used by the selection of the edges the in operator
apply_metrology_model. If the value of the parameter 'rand_seed' is set to a number unequal to the value 0, the operator yields the same result on every call with the same parameters, because the internally used random number generator is initialized with the value of the parameter 'rand_seed'.If the parameter 'rand_seed' is set to the value 0, the random number generator is initialized with the current time. In this case, the results are not reproducible.
Suggested values: 0, 1, 42
Default: 42
- 'instances_outside_measure_regions':
-
The parameter specifies the validation of the results of measurements. If the value of the parameter 'instances_outside_measure_regions' is set to the value 'false', only resulting instances of an metrology object are valid that are inside the major axis of the measure regions of this metrology object. Instances which are not valid are not stored. If the value of the parameter 'instances_outside_measure_regions' is set to the value 'true', all instances of a metrology object are valid.
List of values: 'true', 'false'
Default: 'false'
Execution Information
- Multithreading type: reentrant (runs in parallel with non-exclusive operators).
- Multithreading scope: global (may be called from any thread).
- Processed without parallelization.
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.
Parameters
MetrologyHandle (input_control, state is modified) metrology_model → (handle)
Handle of the metrology model.
Index (input_control) integer(-array) → (string / integer)
Index of the metrology objects.
Default: 'all'
Suggested values: 'all', 0, 1, 2
GenParamName (input_control) attribute.name-array → (string)
Names of the generic parameters.
Default: 'num_instances'
List of values: 'distance_threshold', 'instances_outside_measure_regions', 'max_num_iterations', 'measure_distance', 'measure_interpolation', 'measure_length1', 'measure_length2', 'measure_select', 'measure_sigma', 'measure_threshold', 'measure_transition', 'min_score', 'num_instances', 'num_measures', 'rand_seed'
GenParamValue (input_control) attribute.value-array → (string / real / integer)
Values of the generic parameters.
Default: 1
Suggested values: 1, 2, 3, 4, 5, 10, 20, 'all', 'true', 'false', 'first', 'last', 'positive', 'negative', 'uniform', 'nearest_neighbor', 'bilinear', 'bicubic'
Result
If the parameters are valid, the operator
set_metrology_object_param returns the value 2 (
H_MSG_TRUE)
.
If necessary, an exception is raised.
Possible Predecessors
Possible Successors
apply_metrology_model,
reset_metrology_object_param,
get_metrology_object_param
See also
set_metrology_object_fuzzy_param
Module
2D Metrology