porientationselection

Selects regions from orientation degree.

Synopsis

porientationselection relation threshold [-m mask] [rg_in|-] [rg_out|-]

Description

porientationselection selects regions from their orientation. The parameter relation specifies the order relation to the threshold value that is used to select or not a region.

The orientation value is specified in degree. Is is computed from the moments:

orientation = 0.5*arctan(2*M11/(M20-M02)).

If M20=M02 the region is symmetrical and orientation is every degree.

Parameters

relation is an integer from [-3,3] which specifies the order relation to the threshold value:
- relation = 3: regions with the maximum value.
- relation = 2: regions >= threshold.
- relation = 1: regions > threshold.
- relation = 0: regions = threshold.
- relation = -1: regions < threshold.
- relation = -2: regions <= threshold.
- relation = -3: regions with the minimum value.
threshold is an integer from [0..360] defined in degree.

Inputs

rg_in: a 2D region map.

Outputs

rg_out: a 2D region map.

Result

Returns the number of selected regions.

Examples

Selects exactly vertical regions from the region map a.pan:

   porientationselection 0 90 a.pan b.pan

C++ prototype

Errc POrientationSelection( const Reg2d &rg_in, Reg2d &rg_out, int relation, Ushort threshold );

Version française

Sélection de régions sur leur valeur d'orientation.

Author: Régis Clouard