Hi Chris,

> What I am looking for is a way to get mesh files that capture the detail where it is needed, but
> are economical in terms of overall file size.

MoI's mesher uses some various parameters to help with this, when you export a mesh from MoI a dialog pops up that has various controls on it that you can adjust, there is an overview of the meshing controls here:
http://moi3d.com/2.0/docs/moi_command_reference11.htm#meshdialog


The slider controls the angle parameter, the way that works is that it breaks down the mesh until the surface normals have less than that given angle. That makes for a less dense mesh in flatter areas of the model, and more polygons created in areas that have more curvature to them.

There's also another parameter "Avoid smaller than", that you can use to make a coarser mesh on small sized areas - you enter in a distance there and anything smaller than that distance gets a much coarser mesh on it. This can help to optimize file size by putting fewer polygons on little tiny fillets and things like that. See here for a demonstration on how that works:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3869.70


> So when I mentioned quads, I was thinking that it could be more efficient than triangles.

As far as optimizing file size goes, usually with CAD models using n-gons is more efficient than either quads or triangles. Here's a simple example model being exported using n-gon output:




So note there that when generating n-gons the top face is just one big n-gon. If it were triangles it would have the same number of vertices but a whole lot more polygon faces, twice as many for all the side wall parts, and a whole lot more on the top. If it were "all quads", it would be worse yet because the top face would need to have numerous additional vertices implanted in it throughout in order to try and make a sequence of somewhat regular sized quads that tiled that same area.


> So if there were something that does a better job and it were within my budget, I would consider it.

MoI will likely do a better job, I'd say that its mesher is currently the "state of the art" in NURBS to polygon conversion, it is custom developed and has features like n-gon generation that you won't find anywhere else. And if SolidWorks was in your budget, MoI at less than one tenth the price of SolidWorks should be well within it as well I would think. So it's a good fit for what you are describing here, I would recommend trying out the trial version to see if it is useful for your particular work, there is a 30 day trial version available from here: http://moi3d.com/download.htm .

The best way to answer your question about whether MoI will be useful for you is to test it out.



EDIT: - now that I read your question again I see that your final output destination is 3D printing - usually that will mean exporting to STL format which can only contain triangles within it, so generating either quads or n-gons is not actually feasible for that particular use case. Normally OBJ format (which can contain quads or n-gons, not just triangles) is not used very often for 3D printing.

Usually when people ask about generating quads, they are trying to build an all quad topology to be used for subdivision smoothing in a sub-d polygon modeler, so that's what I thought you were after originally when you asked about that. MoI's mesher still has some nice qualities to its overall mesh generation aside from n-gon generation so it's still worth checking out even if you are not going to be able to use quad or n-gon output since you're doing 3D printing.


- Michael