Mesh > Quadrangulate

Converts the existing polygon selection to quadrangles.

Mesh > Quadrangulate >

The following are the options for the Quadrangulate feature

Angle threshold: Use the slider or type a value to set the limit beyond which two triangles are merged or not (where the limit is defined by the angle between the face normals of adjacent triangles). If Angle Threshold is 0, only co-planar triangles are merged. The maximum angle is 180 degrees. A value of 180 degrees means that all possible pairs of adjacent triangles are converted into four-sided faces.
Keep face group border: Maintains the borders of face sets. When turned off, the borders of face sets can be modified. The default setting is on.
Keep hard edges: Maintains hard edges. If turned off, hard edges can be deleted between two triangles. The default setting is on.
Keep texture border: Maintains the borders of texture maps. When turned off, the borders of texture maps can be modified. The default setting is on.
World space coordinates: When turned on (default), the specified Angle Threshold value is the angle between the face normals of adjacent triangles in world space. When turned off, the Angle Threshold value is the angle between the face normals of adjacent triangles in local space.