SU to Max - Convert to poly creates triangles

harnstein · 12 Jan 2012, 13:36

Hi all,

i actually posted this issue at cgsociety a month ago but got no answer to my question (..yet)

When i import a SU-file into Max, all objects are regarded as mesh objects.
(Btw. all groups with groups inside are ungrouped, so only objects are left in the scene, but this probably has to be like this)

If i turn them to poly objects (for better texturing) some objects are triangulated, some are not..
(It's necessary to have untriangulated objects to apply a uvw unwrap modifier to e.g. achieve a good, random and therefor realistic texture)

Is anyone used to this workaround or has an idea how to solve this?

brodie · 12 Jan 2012, 14:31

I saw a video awhile back on how to deal with this but can't find it now. The jist of it is that you have to model in SU as you would in 3ds max in order to preserve quads. It involved a lot of creating a plane and intersecting it with your geometry to create "loops." It seemed like a terribly tedious process and one which stripped SU of all of it's advantages of speed and ease of use. I came away with the distinct impression that the guy would have been far better of modeling in Max than modeling in SU as if he were modeling in Max. Actually come to think of it he was transitioning to Modo, but same idea.

-Brodie

harnstein · 12 Jan 2012, 17:48

Brodie,

thanks for your reply.

I don't know how far these maybe were issues of older Max versions- Max does import SU-files really nice.
There are quite a few people out there modeling with SU and further process it in Max.
E.g. Ramy Hanna, Peter Guthrie etc.

So there has to be a way (at least i hope )

The strange thing (for me) now is, that i import a model with some objects and convert them to polys-
and than i get this strange, unreproducable result that some simple objects are triangulated, some are not..

Btw, i'm really new to Max but i'm slowly (slowly!) getting used to it. As far as "poly modeling" is concerned,
SU is way better, faster, more intuitive, (for me and you and all here )that's why i keep it!
I changed my type of organizing in SU, i'm modeling each single part of the model as a group or component,
so it's easy to texture, merge, replace etc. everything in Max. That's my basic workflow for now..

PS: You're right about the quads-thing, but even polygons not consisting of only 4 edges work fine.
And you can easily use the "cut" tool to add more "lines" to the object making quads. (Even from unquaded SU objects)

brodie · 12 Jan 2012, 17:57

@unknownuser said:

The strange thing (for me) now is, that i import a model with some objects and convert them to polys-
and than i get this strange, unreproducable result that some simple objects are triangulated, some are not..

Maybe I'm misunderstanding your issue. Can you provide a screenshot or something perhaps?

-Brodie

harnstein · 12 Jan 2012, 18:33

Sure,

here's the shot.

That's the problem with e.g. the unwrap modifier.

In this case there's a wall of wooden boards.
The smaller ones (only the upper ones, not the lower) are triangulated, the other objects -even if the same kind (polycount, chamfered edges..), only shorter- are not.

(It does look a bit strange, this is the backside, the frontside of the short boards came in untriangulated, which is again REALLY strange, "normally" it does triangulate every or no part of each object..)

If it's still unclear please tell me

PS: I just love textures like these, very time consuming to achieve this by hand..

Mr.Plasson · 12 Jan 2012, 22:27

@unknownuser said:

I saw a video awhile back on how to deal with this but can't find it now...-Brodie

I think this is the video:
http://vimeo.com/26453736
It helped me a lot. I hope it can help you too.

brodie · 13 Jan 2012, 13:58

Thanks Plasson, that is, indeed, the video I was referring to.

Harnstein,

That does seem odd that it would be coming out differently for 2 objects with the same features other than length. Perhaps you could post a sketchup file widdled down to just a couple boards or something so I can have a look at it?

-Brodie

harnstein · 13 Jan 2012, 14:25

Thanks Brodie!

I really feel stupid if this is the reason for this strange behavior...

..i guess it may be a problem with backfaces / frontfaces
if that's the reason i get myself into the next corner and fell ashamed for an hour..

I will give it a try after i finished watching the videos from that link (Mr.P, thanks for that!)

Btw, it's not completely necessary to quad everything as far as Max handles SU files really well and i don't want to do all that extra extra work.
The guy in the video is working his .. off to get rid of the inner faces which may probably be handled very well with the ruby "removeinnerfaces.rb" (search google)

I will try several kinds of objects (group, groups in groups, components etc) and see if the problem does come up if there's no backface exposed.
Even if i think i already checked that before as i my some test files- and i always try to keep backfaces where they belong to- inside.

I post the results very soon.

harnstein · 13 Jan 2012, 15:29

Ok, here are some results:

i'm still not sure if this is the only problem / solution, but time will tell.

I made a test file in SU containing

ungrouped objects / grouped ungrouped objects
ungrouped groups / grouped groups
ungrouped components / grouped components

in the first group of 3 all faces were frontfaces
in the second group of 3 some faces were backfaces
in the third group of 3 all faces were backfaces

The result in Max was, that only the objects containing some reversed faces got these faces triangulated. If all faces were reversed, no face got triangulated.

Then i tried some objects, checking what i saw in the video- and i'm quite satisfied with that, i don't see the reason for me to quad everything as long i don't work together with someone who needs quaded objects or whose program triangulates everything if it's not getting quad geometry. Btw, "removeinnerfaces.rb" works great.

One thing to mention is that some backfaces corrupt adjacent faces, as you can see in the Max file.
Some get triangulated themself, some triangulate their neighbours and show themself as a "strange material"

We'll see if there are still problems coming up not getting solved by checking for backfaces..

Anyway, it's a litte piece in the puzzle- maybe someone can take advantage from that in the future..