how can i decimate a hoplessly non-manifold mesh?

<i moved this too its own post, cuz i think the topic kinda changed>

ok, my mesh is DOOMED to be non-manifold for the duration of its natural life. every time i select and delete the non manifold verts and/or edges (i tried both) - i still have some more - i keep doing this until 98% of my mesh is gone and then its manifold.

trouble is that the mesh is ductwork (took me one day to model accurately)

is there anyway to decimate it or lower the face/poly count on a non manifold mesh?

Not without splitting into several manifolm mesh. If there are verts ery clos together you can select them both and combine by using remove doubles. I’d reccoment lowering by hand though, decimation can mangle a mesh a bit. How high is the poly? Ductwork doesn’t sound all that high.

its mega high - i modeled it with my geometry wayyy to tight in acad…fligh % suggested cambo’s pyredux script - ima give it a wack…u got any other ideas?


You can sweat it out by Alt RMB clicking on edges to select edgeloops then Xkey erase edge loop. If your model has long orderly edgeloops, it is not as painful as it seems, and lots of vertices can be removed in a couple of mouseclicks…

Post a blend if you can …

the blend is here:

my stuff is separated by layer

Wow - had a look. There’s a lot here. Had my level 10 finger yoga workout with [ctrl]+[alt]+[shift]+[m]!

I specificly looked at the duct work in the theater building. I assume you want to apply smooth to the ductwork and that is why you are having to deal with non-manifold edges.

There are considerable manifold problems and I don’t have a single solution for you at this moment.

since the geometry of the ducting is symetrical delete half of it and create a mirrored duplicate (linked)- this will half your problem at least.
(1) select and delete half the object [x], vertices (edit mode)
(2) [alt]+[d] (obejct mode)
(3) mirror it [ctrl]+m, [1] or select X (if I remember the placement correctly)
You can also use the Mirror modifier.

In the sections that matter you could try converting the mesh to quad-faces - there are lot of tri-faces used when welding sections together. Because the model is so large I had to scale the model down alot to see the normals - this helped identifying problems.

Did you use a lot of booleans to shape?

If you could highlight your need to get rid of non-manifold edges there might be some better/targeted help to offer.

thanks man…i did what u asked, but why would mirroring make a difference - wouldn’t it just put back whatever i deleted?

i mainly did tri-quad EVERYWHERE…using cambo awesome script…it took me down to 20mb!

btw…what is a decent file size - like when is a file just too big - or does such a thing exist?

linked-duplicated mirror modelling would at least half the mesh modelling effort - like modelling a wheel for a car only once and duplicating it 3 times. Any corrections you make to the first would automatically be done to the other 3, i.e. you don’t have to make corrections 4 times. The data size is also reduced. ( Think about the seats in the theater! )

file size is subjective. Limited mostly by your memory, cpu, etc. Basically you want to minimise as much as possible. For example the model for the interior of the theater could have been done in a separate file from the exterior town. Any animation seqences can be composited together easily. Different issue for game level design.

Another example: a straight tube can be modelled with 4 faces (a open ended cube) with a subsurf modifier applied, simply extrude for curved/tappered tube/pipe - easy to spot/correct problems. Again application of such techniques depends on what your over all goal is.

Another Tip: Concentrate only on the mesh that is going to be seen, i.e. is the top have of the ducting is not going to be rendered don’t worry about it.

Again - we don’t want to waste the effort you have put in to this. It would be good to correct what you have. So is the render turning out wrong? Got an example?

ohhh ok i understand now. the whole root of the problem was that it was model in autocad off of dwgs for an animation of mech systems…

…im still trying to initiate the move to total blendermation…thans for all the help!! :slight_smile:

File conversion will do that to you.

No problem - stick with it.