Non-Manifold Nightmare

Discussion in 'Design and Modeling' started by Sovereign, Oct 16, 2008.

  1. Sovereign
    Sovereign New Member
    I used 3ds max to create a model. I ran the STL check. THOUSANDS of errors! Thousands of open edges. I tried welding individual verticies together to get rid of the problem, but no such luck. I have attached a .3ds file (as the STL export is riddled with errors).

    Joris (bless his heart) has been trying to help me, but so far I've not been able to get past the "non-manifold" block that the servers have up.

    Attached Files:

  2. frigi
    frigi New Member
    There's 2 options for you on this one:

    Trying to fix it as you are already trying. To do do get something like Meshlab and run some cleaning filters in it.
    And there's one more thing you absolutely have to do: close everything, there's a lot of spots where the object simply is open! You need to get a watertight surface on every chunk even if it's intersecting with another part.
    The errors that remain after that can easily be corrected by hand.

    Just recreate it, that's probably easier, faster and cleaner. You can use the existing model as a reference of course. As the complexity isn't too high it's a matter of a few minutes and you can get a perfectly clean mesh that won't drive you crazy when trying to upload.
  3. Sovereign
    Sovereign New Member
    Is there something wrong with my modeling strategy? The "base" for the entire bear part was an OilTank; should I have used something else? (I'm leaning toward a re-do). I know I probably want to minimize use of Booleans because that can create nightmares sometimes in terms of extra verts, open edges etc. etc.
    Last edited: Oct 16, 2008
  4. frigi
    frigi New Member
    Most of the issues are probably because of all the booling which isn't necessary at all in this case. You can actually just use a vert as a base or a cube or whatever as long as it gets you to the shape you need.
    What you could do is use a couple of boxes and extrude/subdivide/deform them as needed and then let them intersect. That would result in a perfectly watertight and manifold model. It will indeed look somewhat fucked up inside as everything is intersecting but that doesn't matter at all.
  5. Sovereign
    Sovereign New Member
    Oh so I do not have to carve everything from the same block. That makes life easier. Thank you for the clarification.
  6. Sovereign
    Sovereign New Member
    *makes liar out of self*

    After three fruitless attempts to redo the model in question, I went back to the old one. I found most of the errors (open/double edges) to be in the nameplate ("Sara") at the bottom. This was done in Rhino and exported, which created a MESS. I redid the nameplate in 3ds max and got rid of thousands of errors (as reported by the STL Checker). As of this upload, only 144 errors remain.

    Any ideas?

    Attached Files:

  7. PeterHermans
    PeterHermans New Member
    Using Materialise Magics (check online if you can find mini magics, I think that´s a free version) I fixed your model.

    It wasn´t quick and easy though because the model was terrible. The final model you deliver does have to be one solid part/shell without intersecting triangles.
    However if you use a tool like magics then often the easier strategy is to make separate parts (each of which has to be solid!) and use the excellent boolean tool in magics to unite everything into one solid part. However, if you do that then make sure that your seperate parts intersect (intersect! not overlap) so you can unite them.

    One other thing, you can use Rhino but generally you are better off using polygon modelling software such as 3DS Max, Cinema4D, Maya, Blender etc. For the simple reason that polygons are triangles (or quadrangles or ngons, but these in turn consist of triangles) and that is exactly what an .stl file is made of. Rhino, Solidworks, Alias Autostudio etc. are all Nurbs based modellers.

    One other thing about the pencilholder model: the scale is off by miles. Please check the images and let me know what the size has to be so I can resize the model and upload it back to you :).

    Attached Files:

    Last edited: Oct 25, 2008
  8. PeterHermans
    PeterHermans New Member
    And the result.

    P.S. Again, the forum is very annoying. There is no indication you have to click the blank space to select a file to attach. Clicking ´upload file´ finalises your message and there is no option of attaching multiple files in one post. And my keyboard/layout is still messed up.

    Attached Files:

  9. Sovereign
    Sovereign New Member fixed it? I'm not sure how I can thank you enough. The scale was supposed to be millimeters, so 152.4 mm or 15.4cm or ~6 inches in height was the goal (from the bottom of the base to the top of the bear's head).

    You said that things were horribly wrong. I would like to know what kinds of mistakes I made so I can learn from this and not have these problems again. I thought modeling exclusively in 3ds max would help (that bear was carved from a single OilTank using Face Extrude and other such tools). The bass clef on its stomach was added via a Boolean or ProBoolean, I don't remember which.

    Thank you very much.
  10. PeterHermans
    PeterHermans New Member
    No thanks ;).

    I changed the scale; however it is still a very big piece and will cost a lot of money.
    As a solid piece it has a volume of 556.3 cubic cm. You do the math. I hollowed it out with a minimum wall-thickness of 1.75mm and now it is 132.2 cubic cm. Still expensive though. Hollowing out is quickly done using magics btw.

    Another thing is that the definition of your model is not very high; that means you will see faceting (triangles) on the model that you might need to sand and polish away. The base is the most obvious 'problem' although you might be happy with the way it is.

    Regarding what you did wrong: you are right in saying that modeling from a single polygon object (extruding, modifying etc.) is the best strategy because in the end you have the end up with a single part that is watertight and does not have intersecting or overlapping polygons.
    However, sometimes things (like the hole to put your pencils in) are easiest to achieve using boolean. But beware that most of the time Boolean or even ProBoolean in 3DS Max will only result in a mess. I only use boolean functions in magics.
    So either create one part of several parts to be booleaned together. In both cases your parts have to be perfect, that means: no holes and no intersecting or double (=overlapping) polygons.

    Attached Files:

  11. Sovereign
    Sovereign New Member
    Mini-Magics is reporting that I have inverted normals when I open the file. I cannot repair with Mini-Magic; should I use 3ds max?

    EDIT: I wanted to see about scaling it down to 5" in height but when I did that in 3ds max then exported to STL, Mini-Magics reported a pleathora of errors that weren't there before... Finally, the "scaled-down" version is 500cm^3 in Mini-Magics instead of 132...where'd that come from?
    Last edited: Oct 25, 2008
  12. madox
    madox New Member
    Magics RP?
    Mini-magics doesn't have any edit capability...digging through the webpage doesn't seem to shed much light on the pricing... how much is it meant to be?
  13. madox
    madox New Member
    Answered my question, around $8000 USD...

    Ouch. Back to Meshlabs for me :)

    Any pointers to opensource/free programs that has similar functionality? (Booleans, Text)
  14. PeterHermans
    PeterHermans New Member
    Hmm I didn't know that mini-magics doesn't have any editing/fixing capability. You could fix it in max but since you have to do it manually it will take you ages.
    EDIT: The inverted normals belong to the inner mesh (to turn the solid part into a hollow part). I get the same message in Magics RP but it is actually not an error! Although I don't know how the shapeways checker will interpret this.

    I use magics RP; I don't know about other software; how much can you do in Meshlabs?

    If the scaled down version is ~500 cm^3 that means that it is a solid version again instead the hollowed out version. If you still have the inside mesh there then there are probably holes in it.

    I scaled it down to 5" for you and it makes a very big difference in volume! Now it's only 77,9 cm^3. The walls are also thinner (just over 1.5mm) so I had to beef them up manually at some points but you should be safe.

    Attached Files:

    Last edited: Oct 26, 2008
  15. PeterHermans
    PeterHermans New Member
    Here's the file.

    Attached Files:

  16. Sovereign
    Sovereign New Member
    Thank you again for your work! Is there some way for me to tell what the volume of the model would be given the height?
  17. WetMorgoth
    WetMorgoth New Member
    Whatever 3D editor tool you have should have a volume calculation ability. If not, and you can code, determining the volume is quite simple. I can point you at a couple of websites that show the volume calculation maths that we use on the backend.