What are the best techniques / addons / tools to simplify a mesh?

I think there is nothing more useful in a 3D modeling app than a good simplify tool, that will get rid of redundant polygons on a mesh without affecting the important vertices that define its shape, making it efficient for whatever use, because when modeling a complex object, redundant polygons are simply unavoidable.

I remember in about 2001, when I was doing a lot of modeling on 3D studio Max for a short period (a few months), there was a plugin that was incredible on simplifying a mesh, it was really god-sent!

Now I can’t find something similar on Blender except decimate modifier which comes with a lot of problems:

It warns me that the mesh is non-manifold and refuses to work. I did some manual corrections with the help of Edit Mode/Select/Non-Manifold feature in vertices mode until no vertices were highlighted, but still it warns me for non-manifold mesh.

I’m already thinking to download a trial of an expensive app just to use such a tool (if it exists and is allowed in the trial) but that’s not a permanent solution! Another desperate alternative is to …manually re-mesh the meshes but that’s extremely counterproductive too!

PLEASE, to help other modellers too, my question is this:

What are the best procedures / addons / even external free -or as a last resort, low cost tools to clean up and make a non-manifold mesh correct and simpler, with fewer redundant polygons, efficiently, with as less manual corrections as possible for v.262?

It depends on what you want to do with your poly reduced mesh
Is it for animation so topology is important or just a static non deforming mesh
How complex is your original model ?
Do you need a real mesh or will normal/bump/displacement maps be acceptable.

Most meshes I want to simplify are static, some will have some parts translated in axis-aligned direction.

  • In sort, I think all my meshes should be considered as static.

  • Not very complex. Most are simple enough.

  • I’m just making real meshes.

Meshlab, free and open source, has several remeshing functions (in Filter -> Remeshing/Simplification/Reconstruction), one of them is the “Quadric Edge Collapse decimation” that works better than Blender Decimate modifier and unlike the Decimate modifier is able to deal with non manifold input.
There’s a version of this function that can preserve the UV too, something the Blender Decimate modifier can’t do.

http://meshlab.sourceforge.net/

Thanks Sanctuary! I have some trouble to make the filter work correctly, but I’ll try now the new version -obviously I have to learn the tools and the environment too.