During photogrammetry workflows it is common to be faced with a mesh that is oriented arbitrarily.
Traditionally the best way of dealing with that is with a transform node and manually orienting the mesh and visually ensuring that it is oriented properly.
The Straighten SOP aims to assist in that workflow by letting the user define a group of polygons that are facing up, and an optional group of polygons facing forward.
The node will then figure out all of the appropriate rotations, in order for the average of the normals of the up group be facing up, and the same for the front group.
Selecting different disconnected areas that have similar normals helps with the orientation
Mesh before straightening
Mesh after straightening
Type of Primitive for the group, Primitive, Edge or Point
Group Name or Geometry Selection that defines what UP means in this mesh
Invert Up Axis
Toggle to orients the mesh towards -Y instead of +Y
Toggle to additionally orient the mesh forward as well as up. Controls the Y rotation of the mesh
Group Name or Geometry Selection that defines what FORWARD means in this mesh