i-d : Yeah, that’s right I tried it last night, and although I couldn’t get it to work with my model… not sure why yet, prob ngon issues, but it works fine with quads. Can anyone tell me if there is a problem with tris and ngons with mental ray subds? I plan to clean it up to be quads anyway. In fact, I believe there is an option to convert ngons to quads in the mental ray options. I plan to look it up tonight, I didn’t have the time last night, but I’m kind of excited about this if anyone has any tips or solutions.
Body topology
i-d
#22
Sorry to push this slightly o.t. but can anyone
explain me how to make mental Ray subd´s work?
Elliotjnewman
#23
try using the collapse hierachy under the subd surfaces drop down. Ive heard MR doesnt like nsided or tri. otherwise perfoem a level 1 smooth before a subdconversion to create all quads (pretty much the same as collapse hierachy…
El
KidderD
#24
i-d : not sure if this is the proper way, but after selecting MR renderer, go to rendering editors->mental ray->and then from memory here… click create and then under geometry approximation select mr subds.
swag
#25
KidderD mental Ray cant render maya subd with ngon or tris u have collapse hierarchy and i mean render poly´s direct with mr
i-d hmm - lets start you have your poly model then go to windows->rendering editors->mental ray->approximation editor in the approximation editor there are 4 section for approximation we want the last one … select ur poly model (with tris:)) say create now a mentalraySubdivApprox Attribute is created … here u can set all mr subd stuff - now render the scene and voila mr renders subd´s
swag
#26
i have problems with some meshes dont know why but if i triangulate the mesh mr have no problem - if the subd looks odd
play with the SubdApprox Attributes (mesh conversion)
i-d
#27
Thanks. Thats what I was hoping for.
Is triangulaing meshes really neccesary?
Why dont mental ray triangulate that mesh for itself and
leave my topology intact?
swag
#28
i-d triangulating meshes is not really neccesary but i have some meshes wont render without triangulating so try it
muckywetnoodle
#29
A couple issues I have with 5+ sided polys or face termination is that it causes operations like tighten to pull that one point to a much greater degree than other selected points (and tends to cause texture warping without special care). This isn’t so much of an issue for something like an elbow that chances are, you won’t be creating a lot of target states with. However, if you have a head with lots of 5+ sided faces and you are planning on building dozens or hundreds of target states, the process of having to constantly mind the smoothing of 5 sided polys can become a major chore and time consideration. (ie: is it quicker and easier to terminate the edges better from the get-go)
I’m not too sure what the term is for how maya’s sub-D’s blend varying detail levels but it seems to do a pretty good job if you have something like a hand that is 2x the resolution of the arm, you can join the poly pieces with 5 sided polys around the wrist and the poly to Sub-D process adds the funky looking blended seam. The resulting model tends to look better than if you were to smooth the blended area with polys (or at least from what I can tell).
Mirai accomodates 5+sides but it starts to slow down as you add detail and more n-gons. There is also no “subdivision” object type.
augustus
#30
Originally posted by swag
i have problems with some meshes dont know why but if i triangulate the mesh mr have no problem - if the subd looks odd
play with the SubdApprox Attributes (mesh conversion)
From Mental Ray documentation:
“Triangles and quads can be mixed in the same subdivision surface, but they may not share vertices.”
Stahlberg
#31
Sounds like Henry Ford’s statement “You can have any color you want, as long as it’s black”. How do you mix a triangle in among quads without having it share vertices with them? 
Elliotjnewman
#32
I think he means you cant have two triangles sharing the same vertex… which makes sense cause you could just create a quad in that case anyways…
swag
#33
Originally posted by augustus
[B]From Mental Ray documentation:“Triangles and quads can be mixed in the same subdivision surface, but they may not share vertices.” [/B]
thats not right - i have here a mix and it works :surprised
augustus
#34
They’re lying then:p
No, it not works, unless you use mesh conversion (I just saw this option, was there here before 5.0.1 ?).
Regarding to my prior experiments, rendering polys with this method only usefull if you use plain colors or maybe 3d textures. When 2d textures used, you get blurred results most of time. I’ve exported same model as mi file, both using Maya subd and using a Mental Ray subd approximation to see where the problem is. Uv’s were different. :shrug: Maybe you know how to correct this?
-Sorry for my terrible English
swag
#35
sorry - we talk at cross-purposes i have problems with “mesh conversion” on too - some meshes wont render -
there is only a error “polySurfaceyxz, polygon mesh cant be exported as a subd surfave” nothing more
i have render a textured mesh again and yes the textur is blury (not much) dont know why
is it a filtering problem?
all uv´s looks ok on the mesh
Marcel
#37
I agree with CLAW, great work on the fots! :rolleyes:
Do the five sided polygons have any usefull effect on the surface, or are they purely for terminating/adding edges?
Somebody on the first page mentioned that poles are bad, I find exactly the opposite: you need poles to make a good surface. I use them to create nice corners on my model, like the corner of the jaw, the chin, the nostrils, etc. This model by Syomka is a great example:
http://www.metagons.com/images/SI0205.jpg
for poles!
Stahlberg
#38
Thanks!
I try to make each 5-side serve two purposes, 1. to end edges with less fuss, and 2. to create a gentle bump. (If I want a sharper bump I use a triangle.) If it has to be super-smooth I make it quads.
And yes, I’m all for poles too.
Marcel
#40
A pole is a vertex with only 3 edges instead of the usual 4.
They do create a small bump in the surface, which can be negative if you need a super smooth surface like a car body or other mechanical objects. But for organic modelling that doesn’t matter at all.
I don’t know whether a vertex with 5 or more edges are also called poles.