What are these speckles?

Discussion in 'Shapeways Shops' started by UniverseBecoming, Mar 11, 2013.

  1. UniverseBecoming
    UniverseBecoming Well-Known Member
    I tried numerous creation methods for the two acceptable formats, but everything I tried gave me these speckles from the default renderer.
    [​IMG]
    Also, a few of these same speckles can be seen in the default render of this popular figurine.
    [​IMG]
    You can see them in front of the ear, on the nose, rear leg and on the side of the torso. However, I looked at numerous other default images pertaining to this material and the images look perfect. I'm assuming it is related to the topology and I think if I submitted a perfect quadrilateral mesh it would look great in the default render, yet, their can't be that many people submitting perfectly renderable meshes. Or am I wrong?

    Anyway, let me know what you think. I'd like to do some products in this material, but I would need to correct this issue before moving forward.

    James
     
  2. shariff
    shariff Well-Known Member
    u could always use the despeckle filter in gimp or maybe other image editing and creating softwares.

    if u use blender like me try raising the render sample value some in the render panel.
     
  3. UniverseBecoming
    UniverseBecoming Well-Known Member
    Those are great tips! Thanks for posting! :)

    But no, I'm not doing the render for that. That's Shapeways' autonomously rendered image that shows up when you upload a 3D file. Here's my render,

    [​IMG]

    Mine is perfect as you can see. When I get some time I'll work on seeing exactly why Shapeways' render engine is doing this. It has something to do with the underlying topology I'm sure.

    Oh and I forgot to provide attribution. The cartoon artist that did the drawing this model is based from is Francesca Hause. Her website can be found here and the actual drawing can be found here.

    The unicorn, as seen on Shapeways' front page is by HashBrony.
     
  4. wedge
    wedge New Member
    Hmm how do you apply the color? With a Texture?
    I have seen similar Artefacts on other Systems, where the Texture or the UV map was the Problem.
     
  5. UniverseBecoming
    UniverseBecoming Well-Known Member
    Yeah, I have an image map texture on this model, but it will also work by doing vertex color and no image map. In both instances the speckles appear.
     
  6. wedge
    wedge New Member
  7. UniverseBecoming
    UniverseBecoming Well-Known Member
    Good find. I'll keep this in mind next time I work on this.
     
  8. UniverseBecoming
    UniverseBecoming Well-Known Member
    Ok, I uploaded a sphere that has perfect topology and still got the speckles. I then uploaded the same sphere but rotated it 90 degrees before uploading. If you have a compatible browser you'll be able to see, in the APNG below, that the speckles do not change position when blinking between the two images that correspond to the two uploads. Thus confirming that I was wrong about thinking that it could have something to do with topology.

    [​IMG]

    Based on Wedge's observation it is some kind of error rooted in the way the render engine interprets curved surfaces.
     
  9. shariff
    shariff Well-Known Member
    oh i see ur on about the shapeways version of ur 36o deg view that's something that will never change cos that's how the actual machines print out the objects we model, pure topology, i've been told also that only polished materials will be smooth and clean surfaced unless u really raise the toplogy but that raises the polycount greatly, remember 1,000,000 polys is all they accept as a limit and that adds quickly in 3d modeling for models u want to make on shapeways.
     
    Last edited: Mar 16, 2013
  10. UniverseBecoming
    UniverseBecoming Well-Known Member
    That's great advice, but the topology has nothing to do with it as you see by the results of my sphere experiment. :) I just finish a cartoon husky design of my own and the speckles are really bad on this one. See the default image here,

    [​IMG]

    The 3D viewer rendering system works fine, for models under 64 megabytes, if over 64 megs the 3D viewer doesn't activate. It is using a complete different rendering engine as far as I can tell.

     
  11. bartv
    bartv New Member
    Hmmm weird. I think it's related to the ambient occlusion pass. Is the geometry in the affected areas completely flat, or does it contain micro geometry? (Hairs, fur?)

    Bart
     
  12. UniverseBecoming
    UniverseBecoming Well-Known Member
    The sphere I experimented with is a prefect polygonal sphere with no surface deviations at all. If you can see my animated PNG above (needs a compatible web browser to see it) You'll see that the topology has nothing to do with it. That is the same sphere rotated 90 degrees, yet the speckles don't change position. The two images were taken from two different uploads of the same sphere; the only difference was I rotated it 90 degrees.
     
  13. stop4stuff
    stop4stuff Well-Known Member
    Hang on, I just cleaned my screen - most of the speckles are gone, but the ones that remain just look to be a moire effect of the rendering. But then again I am reg/green colourblind.

    Paul
     
  14. UniverseBecoming
    UniverseBecoming Well-Known Member
    Oh wait, I cleaned my screen too. PROBLEM SOLVED! HAHAHA! :laughing:

    I did see this same error before long ago. It's been too long though and I can't remember what rendering software I saw it in.