How smooth is smooth?

Discussion in 'Design and Modeling' started by Sovereign, Jul 23, 2008.

  1. Sovereign
    Sovereign New Member
    I use Rhino 3D 4 for my modeling. It can natively export to STL format, however this requires a NURBS to mesh conversion. The model I currently have up converted successfully, but there are obvious faces to the model despite me wanting it smooth.

    The model is here: http://www.shapeways.com/model/1129/srv_01_survelliance_vess el.html

    Will this print smoothly or should I mesh with more polygons?
     
  2. robert
    robert New Member
    Hi Sovereign,

    Nice model. Do you have more to show us? I would be very interested to see them!

    I looked at your model. I would suggest to mesh with more polygons. Especially the body of the craft will not come out completely round. You will see some of the edges of the triangles.

    You will happy to hear that in our next release of the portal there will be an option to make your model view-only.

    Best regards,

    Robert
     
  3. Sovereign
    Sovereign New Member
    Apologies for the large images (900x600)... These were rendered in Rhino 3D (the application in which the model was designed).
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    Front

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    Perspective

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    Rear Perspective

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    Side

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    Top

    I did create a mesh with higher polygons, but the model was rejected and the system did not tell me why.
     
    Last edited: Jul 26, 2008
  4. robert
    robert New Member
    These renderings look fine to me. Are these from the same model? What is the polycount?

    Best regards,

    Robert
     
  5. Sovereign
    Sovereign New Member
    3ds max 2009 x64 jammed trying to export to Autodesk Collada (DAE file). I am going to try to use the STL format, but I am going to send it to your support staff as I know most likely the automated system will reject it (most likely as being too big either in volume/dimension or filesize).

    These renders are from 3ds max (mesh, not NURBS).
    [​IMG]
    Front

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    Perspective

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    Rear Perspective

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    Side

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    Top

    30,550 polygons and 19,033 verticies according to 3ds max. I only wish the front of the ship wasn't so pointy...
     
    Last edited: Jul 26, 2008
  6. Barry_FM
    Barry_FM New Member
    I just posted to another thread on a similar topic, hope this is helpful:

    Standard rendering in 3ds Max (and to some extent all 3D renderers) has very little to do with the smoothness you will see in a final 3D printed model. Your expectations may not be met if you rely on the visual smoothness of a rendering.

    To get a better idea of how the final model will look when printed...

    A. Apply the Smoothing modifier to all objects and leave it with its default settings ( = Disable all smoothing groups in the modifier, and make sure nothing is checked such as Auto Smooth.) This effectively removes all renderable smoothing effects from the model.

    B. Render the now flat surfaces at a very high resolution. Now you should be seeing a pretty good preview of the raw polygon shapes that make up your model's surface.

    Even with these steps, the render will always be averaging the surface to make it into pixels so you still will have some very small 'fake' smoothing effect.
     
  7. Dalhimar
    Dalhimar New Member
    Good work, Along with what barry said, using splines and nurbs is a fast way for the computer to calculate the mesh, though it dose give a very smooth initial look, it is doing that by using a special smoothing technique inherent to splines/nurbs. But once it is converted to a more standard type such as a "Mesh" or "Poly" inside of 3DS max and other programs, it reverts from the smoothed look caused by the spline/nurbs algorithm to the actual mesh, which contains much fewer polygons and vertices.
    Just so that you can get a more accurate feel for the object before exporting, you can press "F4" in 3ds max to highlight the "Edges", or lines between each vertex.
    Keep up the good work though.