With an assembly selected in a 3D area, selecting this tool will merge geometry using the same material into a single geometry.
Smooth Normals
This tool can be used to average the normals of the geometry to appear smoother during rendering. Also vertices having the same position and normal direction will be replaced by a single vertex, thus reduce the size and complexity of a 3D model.
Flip Normals
Clicking this tool will have the selected objects normals flipped.
Fix Scene Normal
Generates appropriate normals to the selected geometry.
Mesh Decimation
Reduces the number of polygons in the selected geometry without affecting its appearance greatly. This is another tutorial on the subject.
Info
Clicking this tool will display Geometrical Info dialog, showing the number of Objects, Vertices, and Polygons in the selected geometry. Knowing the number of vertexes and polygons can help a user estimate the size of the output file. This might make the user ignore some details, for sharing efficiency.
