LinkingRule - PPilger/text-detection GitHub Wiki
These rules enable you to define if a link between two features is valid or not. The rules can be used in [feature linking](feature linking).
Attribute based LinkingRule
Validity is determined based on certain attributes.
Usage
- Use
AreaGrowthLinkingRule
if all text that should be detected has the same size. This rule benefits features that are in one line. - Use
BoxDistanceLinkingRule
ifCenterDistanceLinkingRule
can't be used. - Use
CenterDistanceLinkingRule
if every letters can be detected as a single feature.
For feature linking use one of the two distance based rules and, if desired, the area growth based one.
Parameter
areaGrowth
The area growth is calculated with area of the linked feature - sum of the area of the two sub features
.
A reasonable maximum value is the maximum (box-) distance times the maximum height of two letters.
distance
Should be choosen as small as possible to prevent linkage with undesired objects.
FixedDirectionLinkingRule
This rule can be used to define if two features may be linked in a certain direction or not.
Usage
Use this rule if all text you want to detect is oriented in one direction.
Parameters
angle
Defines the direction of the text. The parameter has to be specified in radians.
Image coordinates are used (the origin is the top left corner). So the angle 0 is horizontally and increasing the angle equals a counterclockwise rotation.
width
Defines the valid distance of the features in the specified direction.
height
Defines the valid overlap of the features in the specified direction.