# Alignment and right angle detection (Burns, Grompone)

From OTBWiki

- The Segment detection was done using the LSD algorithm ( a fast Line Segment Detection algorithm).

see otbLineSegmentDetetection.{h, txx}

The result is a linear-time Line Segment Detector that give accurate results and a controlled number of false detections, without the need of parameter tuning for each image.

the publication of Grompone, Jackubowiscz , Morel & Randal was followed for the implementation : (see : http://www.cmla.ens-cachan.fr/fileadmin/Membres/jakubowicz/pdf/lsd.pdf)

- A class for right angle detection was implemented too, it takes a lineListType as input and compute a pointSet containing the coordinates of the right angles, and the segments that form the right angles.

see otbLineSpatialObjectListFilterToRightAnglePointSetFilter.{h, txx}

**The aim of those two classes is to do a gemotry-based unsupervised (LSD an rightAngle CLass are parameters tunning less) urban area detection**