Structure that contains the parameters that control the extraction of solutions from the ShapeFinder accumulator. More...
Data Fields | |
int | LocA |
Minimum rotation difference for two results. Set to a sufficiently large value to avoid co-located results that only differ in rotation. | |
int | LocR |
Minimum scale difference for two results. Set to a sufficiently large value to avoid co-located results that only differ in scale. | |
int | LocXY |
Minimum distance for solutions in the coarse layer before correlation hill climbing happens. | |
int | MaxNumSolutions |
Maximal number of solutions to return. Set to a sufficiently high value to avoid loosing results because no available slots for potential candidates are left. | |
int | MinimalThreshold |
Absolute quality threshold a result must exceed to make it into the result list. Depending on the value of Precision this is either an (open ended) feature count (Precision == 0 ) or a quality value from the range [0...100] (Precision > 0 ). | |
int | Precision |
Defines how many and which search phases will be carried out. More... | |
int | RelativeThreshold |
Defines the quality span between the best and the worst result candidate. | |
Related Functions | |
(Note that these are not member functions.) | |
cvbbool_t | GetSF2SearchAllPars (SF sf, TSearchAllParams &SearchAllPars) |
Queries the currently set parameters that control the generation of a list of solutions during a ShapeFinder2 search operation. More... | |
cvbbool_t | SetSF2SearchAllPars (SF sf, TSearchAllParams SearchAllPars) |
Sets the parameters that control the generation of a list of solutions during a ShapeFinder2 search operation. More... | |
Structure that contains the parameters that control the extraction of solutions from the ShapeFinder accumulator.
At the end of the first search phase of a ShapeFinder2 model (functions SF2Search and SF2SearchEx), the preliminary candidates for further refinement are extracted from a ShapeFinder search accumulator according to the parameters defined in this structure (see also the chapter Preliminary Search):
MinimalThreshold
is generated and sorted by descending quality.RelativeThreshold
percent of the highest entry are deleted (e.g. if the highest quality in the list is 60 and RelativeThreshold
has been set to 50
then all list entries with a quality of less than 30
are discarded).LocXY
, LocA
and LocR
is made on all the remaining entries in the list: If a higher quality result has a lower quality result nearby in terms of position, rotation or scale that violates the LocXY
, LocA
or LocR
threshold, the lower quality value(s) will be erased, making sure that LocXY
is the minimum distance between nearby results and LocA
and LocR
are the minimum scale and rotation difference for nearby results (all three locality thresholds are checked simultaneously).LocXY
is being applied in the coarse layer of the first search phase. This means that the locality is not given in pixels of the original image, but in pixels of the coarse layer (which must be multiplied by a factor 2coarseScale to map to the original image. LocA
and LocR
are usually given in accumulator distances in the scale and range "direction", making it difficult to map these to useful values. Usually an extremely large positive integer value should therefore be assigned to these two thresholds.Precision
is greater than 0
) which may lead to situations that two results ultimately end up closer to each other than the LocXY
parameter would allow.MaxNumSolutions
only the best MaxNumSolutions
entries are kept.The search parameters are a property of a ShapeFinder2 model and will be set to the following default values:
Parameter | Default Value |
---|---|
LocXY | 10 |
LocA | 60 |
LocR | 2147483647 |
MaxNumSolutions | 100 |
RelativeThreshold | 78 |
MinimalThreshold | 10 |
Precision | 2 |
The currently used values may be queried with the function GetSF2SearchAllPars and modified with the function SetSF2SearchAllPars.
The constant SAP_DefaultParams defines a useful set of default values.
int Precision |
Defines how many and which search phases will be carried out.
Value | Meaning |
---|---|
0 | Only a ShapeFinder-like search will be performed giving only rough precision in location, rotation and scale. |
1 | The ShapeFinder search will be followed by a correlation step in the coarse layer giving good precision in location, rotation and scale. |
2 | The ShapeFinder search will be followed by a correlation step in the fine layer giving optimum precision in location, rotation and scale. |
Higher values here will lead to an increase in processing time.