3D Max - inverted normals (bis)

Discussion in 'Software and Applications' started by Magic, Apr 2, 2009.

  1. Magic
    Magic Well-Known Member
    Sorry Animemi, I am posting exactly the same subject as you.
    I have the same problem (inverted normals) that probably comes from the use of booleans in 3DS Max.
    My object is quite complex, and I did it at least 3 times and still there is a problem.
    So I try with something (that I thought was) easier.
    But even with 2 cubes, I got the inverted normals and I cannot figure out where those inverted normals actually are.
    It drives me crazy.
    How can I fix a problem I cannot see?
    I try with edit normals in 3DS MAx and all seems fine. And I can see no hidden geometry, no overlapping faces.

    So, what wrong ?

    Can anyone help me, please?


    Attached Files:

  2. virtox
    virtox Active Member Moderator
    I had a look at your test, indeed shapeways bounces it, although it looks perfectly normal.
    However, just importing and exporting and it uploaded fine..

    I used binary STL format, and after some testing this seems to be it !

    When I export from max in ascii STL, shapeways says : inverted normals, when exported in binary STL, it is accepted.

    Give binary a try ?

    Hope it helps !

    Last edited: Apr 2, 2009
  3. Magic
    Magic Well-Known Member
    Thank you Virtox.

    I am afraid you are right. I was trying to find a rational reason where there was none. It's just... magic!

    Actually I turned the STL to ASCII because I though I would be easier to check if there was an issue on my complex model (that actually is not so complex, but just more than 2 cubes), and that's what caused the issue in the simple model.


    OK, time for me to go to bed, I guess...
    ANIMEMI New Member
    Glad to hear that.

    I am pretty sure I used Binary on all my attempts (I think its the default and has smaller file size). So I think my mesh must be a mess somehow.
  5. Magic
    Magic Well-Known Member
    Hi Shapeways team,

    Any chance to fix this issue with ASCII STL?
    This is not very important, but if it's not meant to be fixed, you could indicate that only binary STL are supported as an input.
    Thank you!
  6. Whystler
    Whystler New Member
    Just a lil tip:

    If you are making hollow models in Max, it's easiest to use the "shell" modifier, rather than to use subtractive methods.

    To do this, select your model, and then go to the modifiers menu, choose parametric deformers, and choose "shell"

    Automatically, the program will use the surface of your original model as the "inner surface" of the shell, and it will "push out" a second outer surface ... usually quite far by default if you haven't used it yet. But you can go into the settings of the shell flyout (to the right side of the window), and change the amount it pushes out the outer surface. Alternatively, you can also specify the other parameter, which instead of using your original model's surface as the inner surface, instead uses it as the outer surface of the shell, and pushes inwardly.

    Last edited: Apr 6, 2009
  7. ArMOO
    ArMOO New Member

    I have been using Binair Stl for s while and had problems in printing. I made them in solid works. I had to open them in meshlab to make them printable ( dialect problem ).
    I change the settings to Asci in solid works and also changed the settings to fine ( before I tried to get the highest resolution as possible ).
    Since then I don't have any problems anymore. In my case asci files don't create problems. Most of the time now its how I modeled something if I have a problem.

    Greetings AO
  8. Magic
    Magic Well-Known Member
    To Whistler:
    Thanks for the tip. Actually I used no substraction nor intersection boolean for the Zen box. The main parts are done with shapes that I extruded. The problem is that there are mainly 3 profiles (or say, "sections") and I had to "glue" them together. For that I used the union boolean, but most of all I tried to add vertices in some shapes: those vertices were useless to this shape itself, but were present in the following shape section (it helps to keep the consistency of the polygons).
    Nevertheless, I had to manually clean the model (a lot of internal faces and even edges, and one strange polygon).

    To AO:
    If the STL format are supported, all the dialects should be supported (or alternatively you should precise which dialects are supported). I understand that ascii and binary formats work most of the time, but I have a very simple example (in attachment in my initial post) where the ascii does not work and the binary does work. I used to be a programmer: if you can reproduce a bug, then this bug should no more exist.;)
    What exactly is the fine setting related to?
    Last edited: Apr 6, 2009
  9. ArMOO
    ArMOO New Member
    Hi Magic,

    In solid works the settimg fine is an automatic setting.
    You can choose :
    coarse: deviation tolerance 0.1199 and angle tolerance 30 degrees.
    fine : def tolerance 0,0462 and angle tolerance 10 degrees custom: deviation and angle tolerance can be changed more rough or fine.

    Since I changed to ascii and to fine I don't have problems anymore.
    Greetings AO