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# RegionPerimeterLength

Header: | AVL.h |
---|---|

Namespace: | avl |

Module: | FoundationBasic |

Computes the length of the input region perimeter.

### Syntax

C++

C#

void avl::RegionPerimeterLength ( const avl::Region& inRegion, float& outPerimeterLength )

### Parameters

Name | Type | Default | Description | |
---|---|---|---|---|

inRegion | const Region& | Input region | ||

outPerimeterLength | float& |

### Description

The operation computes the perimeter length of a region **shape**. Because regions are pixel-precise, the literal computation of the length of the region contour would lead to the overestimation of the diagonal edges. Therefore, the filter employs the following equation to approximate the result:

Where

**sides**denotes the number of pixel sides adjacent to the region background**vertices**is the number of turns to right during clockwise walk along the pixel sides of the region boundary**a**,**b**are constants defined as follows:

To compute the actual contour of the region, one can use RegionContours filter.

### Examples

### See Also

- RegionContours – Computes an array of closed paths corresponding to the contours of the input region.

- RegionDiameter – Computes the longest segment connecting two pixels contained in region and its length.