Hello

I want to reduce the numbers of polygons of a 3d object from(8000) to (800). I have tried to reduce them using decimator slider button but I get the error

ERROR: No manifold Mesh

Anybody knows what means this message and how can I do this reduction? (My 3d object is not a triangle mesh)

Thanks in advance

Josu

there are good threads on this on elysiun

but the summary are as follows,

a non-manifold mesh has edges which are used by two or more faces. They don't make remote sense in a physical world because there is no inside nor outside.

quick way to make a non manifold mesh: add a cube, extrude one edge.

I would suggest that you look for the problem by turning off the double sided button in the edit buttons, and looking for which side is black in your model. Recalculate normals, and look, and ...

other approaches: split your mesh up into multiple objects, and see which ones will not decimate because of that error. When you find (and fix) the problem, join them back, remove doubles, and desimate away

others have suggested using remove doubles on non-manifold meshes (tun lim up) as a decimatior-like function. Decmiatior is preferred though because it considers the bends in your mesh more than remove doubles.