We purchased a model (of an airplane) as an .OBJ file. The file is much higher resolution than necessary for our purpose, and we would like to reduce the resolution in order to reduce the file size.
I have tried the “Reconstruct Subdiv”, but I get an error message that says “Mesh contains triangles. Operation canceled.”
Is there another way to reduce the resolution/file size of this .OBJ file?
Thanks,
Rob
Well dont know if this might help or not but turbo smooth and tessellate do help get rid of triangles, so u might want to use that before you use the thing your talking bout, or just go into it and reduce it by hand. I will do it the hand way because u have more of a controll what u get rid of and what u dont.
If you have Maya or similar package, you can open the OBJ, select the object, convert Polys to SubD. It should remove the triangles. (In Maya), you can also choose the Polygon Options to Cleanup or Quandrangulate but I’m not quite sure if that’ll do the trick like the Poly to SubD conversion would.
Save the object as an OBJ, then import the file as a tool in ZB.
Hope this helps because deleting edges by hand so you can make quads out of triangles is tedious. :rolleyes:
hi!
yep, the only good method i know is to convert the polys to subs and then colapse the hierarchy of the subs. that way all the triangles will be converted to nurbs- the price you have to pay is the “mesh resolution”-that´s the poly number, which will be considerably higher after the operation. after that all you have to do is to convert the tesselated mesh back to polys, import it into zbrush and reconstruct history step by step.
the quadrangulate method don´t work, not a chance, somewhere i found a mathematical explanation of this fact- i forgot where that was.
(Maya) 
Convert Poly to SubD. Then Convert SubD back to Polys Options (I forgot to mention returning back, which Bogtalan caught). In the Options, make sure to pick Vertices and set the Level to Zero. This will prevent adding geometry.
Hope you have a 3D package that can assist you or this won’t be much help. 
Bogtalan is right about Quadrangulate. Maybe that’s why I haven’t found a use for it yet. 
I have a question on this topic. Everyone reccomends converting to Subd (which would remove the triangles) and then converting back to polys at a level zero or taking it into Zbrush and using reconstruct subdiv history to a lower level. My question is this- how does this actually reduce the poly count? Am I missing something here? If I convert to subd, then back to poly with vert option at zero- I end up back where I started. Same thing if I use reconstruct subdivision. If I start a model with triangles- upRez it to remove triangles- I’m still going to get those triangles back when I down rez… or maybe I just don’t get it.
Zbrush cannot do what you want, there was a poly reduction tool back in the day (1.23?)…
I prefer the latest version of Blender, although any 2.0+ version will reduce polys using the Decimate modifier, 2.4+ has a Poly Reduction script available (under Scripts>Mesh>Poly Reducer) that does a great job knocking down the polys while maintaining UV coords (very important if the model has a texture applied to it already).
3dsmax has a good non-destructive modifier for reducing polys that maintains UV coords, you can then export the object as obj with the modifier applied --at least v5.1, my latest, Im sure the tools have advanced in that app.
Also, look into nvidia’s meLODy… not sure if it is still available or what development state it is in, but did a pretty good job for me a couple years ago when I tried it then.
I am sure you will run into other apps if you do some googling on poly reduction tools. I highly recommend Blender, though… that app is advancing very quickly and works well with Zbrush.
If you’re using Max, there’s a script on scriptspot.com called Quadrangulate. That’ll do the job for you, well, mots of it. Will convert as much as possible to quads.
First off… Thank you all for the responses. I appreciate each of you taking the time to give input.
Unfortunately the only tools I have are ZBrush2 and Lightwave 7.5. I heard from a contact that there is a plugin called QEMLoss for Lightwave that might help.
This whole world of model creation is way over my head. 
It’s amazing what you guys can do. I am just a programmer trying to get some .OBJ files to fly around in an animated scene.
I’ll let you know if I’m successful with QEMLoss (or any other method)…
Thanks again for the responses…
Rob
Hello, there is very good command line tool for polygon reduction. You can download it here: http://polygon-reducer.pc-guru.cz