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How The F*#% Do I Model This? - Reply for help with specific shapes - (Post attempt before asking)

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  • Grubber
  • Laon

    Thank you guys so much, I have been trying to do this for days now, thank you so much!!!!

  • okidoki
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    okidoki triangle

    Because there are three holes i would suggest making life easier and choosing an outer cylinder with edges divisible/divadable by three.. for example 15.. i also took 15 for the inner cylinders because the angle fits better.. (here centered on the top border).


  • kuronekoshiii
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    kuronekoshiii polycounter lvl 2

    Sorry for busting in, but I really wanted to know how to subdiv model this one without Sharp edges.


  • FrankPolygon
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    FrankPolygon veteran polycounter

    @kuronekoshiii The support loops running parallel to the cylinder wall segments are disrupting the curvature when subdivision is applied. Adjusting the number of segments in the larger curve, so the existing edges can be used as support loops for the cut out, should resolve the issue.

    wirrex recently posted a great example of how this can be done. Link to that post: https://polycount.com/discussion/comment/2769388/#Comment_2769388

    There's also a couple alternate topology layouts that can be used. Link to that discussion here: https://polycount.com/discussion/comment/2757713/#Comment_2757713

  • kuronekoshiii
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    kuronekoshiii polycounter lvl 2

    @FrankPolygon Thanks for the links! I'm having a hard time since the model is from the client-premade 3D, so I decided not to remodel it, but I think I have to. Anyways, thanks!

  • HAWK12HT
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    HAWK12HT polycounter lvl 10

    Client stuff always get remodelled otherwise there be no client :D

  • rage288
  • macaron10

    Hello, dear, I ran into a topological problem, if you can call it that.

    Please who can help?

    I will be very grateful.

  • count23

    Hi folks,

    I'm having trouble with a shape here, not sure if i'm on the right path or not.

    The shape described here in these images, essentially it's a cylinder with a perpendicular circular extrusion that seamlessly moulds into the shape of the rest of the main cylinder it's joined to.

    This was my most recent attempt. I effectively created a circle perpendicular to the main cylinder with roughly the same number of divisions for the cylinder that would join to it and quadded the area up.

    It looks ok at some angles, but others it doesn't, either presenting as a little too flat or with some hard edges appearing in the shading where the cylinder starts changing shape:


    Am I on the right track ad just need to do a few tweaks? or is there a better way to accomplish this shape? ( I should add the lines that are in blue are bevel edges providing control loops on each side of the highlighted mesh in a proper quadded topology (arc mitre for the middle bit).


  • kuronekoshiii
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    kuronekoshiii polycounter lvl 2

    But if the payment is low, remodeling is not a good idea 😥

  • kuronekoshiii
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    kuronekoshiii polycounter lvl 2

    But if the payment is low, remodeling is not a good idea 😥

  • count23

    Thanks for the reply. I think the bit that sticks me TBH is how to effectively cap the end of that cylinder while maintaining the proper profile of the cylinder itself. Is that all done by hand? Or did you blend a quad sphere with the end of a cylinder? the main reason i didnt try to cylindrically cap the end of my bay was because i couldn't effectively marry a quad sphere to the cylinder i was using. Part of the reason why my shape is so off is because i originally created the perpendicular circle to the cylinder, then quadded up the two loops and added some dividing edge loops.

  • count23

    Thanks, that really helps clear things up, the approach you described is a lot easier than linking a quad sphere. I tried that after your first response and while it achieved the results, it was very limited (for instance, in the actua model i'm copying, since the cylinder is conical, that means the hemisphere needs to follow that angle to flatten out, a quad sphere didnt' acheive that).

    Just a quick question on the gif you sent of your approach. So the Extrude/rotate and scale y+z you proposed went by a little fast. If i understand this correctly, what you're advising to do is extrude the edges you highlighted on an equivilent shape, then rotate down on the X axis using the original row as an origin to approximately halfway between the two edges i want to bridge, then use scaling on Y and Z to bring the extruded curve into the final right position?

  • okidoki
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    okidoki triangle

    Hmm interesting.. tried to remodel the original approach with the side view and.. doesn't get that bulgde... (ignore the none roundness and the little other artefact 😉)


  • wirrexx
  • FrankPolygon
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    FrankPolygon veteran polycounter

    @count23 Correct. Extruding and rotating the new edge into place ensures that the longitudinal edges remain parallel, until they are joined with the surrounding geometry. Constraining the scale operation by length and height ensures the width remains consistent and this helps prevent unintended surface deformation.

    Without getting too far into the technical details, Catmull–Clark subdivision smooths by averaging the surface and this comes with some inherent accuracy limitations. Substantial shape and topology issues are usually easy to spot, when they produce obvious surface deformation, but abrupt changes to the surface shape, segment spacing and topology flow of the mesh can also produce subtle inconsistencies. Which affects the quality of the edge highlights and surface reflections.

    These subtle types of surface artifacts can be difficult to spot and matte viewport materials tend to obscure both major smoothing and minor flow artifacts when modeling but the issues will show up when baking normals or using high gloss materials with sharp reflections. So, it's generally considered best practice to use a view-port material with bright highlight and wide roll-off. Materials with sharp highlights and surface reflections can also be used to evaluate surface quality. It's also considered best practice to do a detailed flow check of all areas that need high quality surfaces. Disruption or turbulence in the reflection map's lines generally coincides with surface quality issues.

    Here's an approximation of what the original topology looks like when viewed with a variety of different view-port materials. The subtle shading artifact around the shape transition is still visible, it's just harder to see without rotating the highlight or compressing the levels in Photoshop. Smoothing and flow artifacts are lot easier to identify when using a more reflective material. Deflection and swirling in the reflection map shows where the changes in segment spacing generate turbulence in the surface flow.

    In the original question, the second wire frame shows a slightly different topology layout that produces a stronger smoothing artifact and noticeable flow disruption. The increased flow deflection around the added support loops does suggest that moving the rear support loop away from the shape transition and routing the topology flow in a more consistent pattern should resolve the visible smoothing artifact.

    Going back to the original example, moving the rear support loop away from the shape transition produces a more consistent segment spacing. Which reduces the turbulence in the reflection map and the visibility of the smoothing artifact. Pushing the support loop closer to the shape transition has the opposite effect. While the result isn't perfect, moving the rear support loop should resolve the smoothing artifact near the shape transition.

    Maintaining a relatively consistent segment spacing and simplifying the topology routing produces a much smoother surface flow and shape transition.

    Below is a comparison of the different segment spacing and topology layouts. Using more geometry can make it easier to add details to a contiguous mesh but there's also diminishing returns and after a certain point it doesn't make sense to keep re-working a mesh that's good enough.

    The hull in the reference images looks like it has a matte finish and minimal surface details. If the player or viewer isn't close enough to see any minor artifacts then there's usually going to be minimal benefit to improving the results beyond what's required for the intended use case for the asset.

    Another thing to consider is that the hull form is a series of complex, compound curves with a lot of intersecting shapes. So, it probably makes sense to block out all of the larger forms first then work through another block out pass and add all of the smaller details like the landing bay doors. If most of the surface details like panel lines, greebles, windows, etc. will be added with a texture then the base mesh can be kept fairly simple.

    Avoiding unnecessary complexity will make the modeling process a lot easier and can help prevent surface flow issues and visible smoothing artifacts. Below is an example of how consistent segment spacing and simplified topology can be used to create the basic shapes while also minimizing flow disruptions.

    Recap:

    Use a viewport material with a visible highlight or reflection to evaluate surface quality while modeling.

    Flow check parts that require high quality surface reflections.

    Block out the larger forms then add the details.

  • okidoki
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    okidoki triangle

    I was refering to the OP's question about: Am I on the right track and just need to do a few tweaks? And was also somekind wondering why my simplest re-modelling (the same topology) doesn't have such a clearly visible buldge.. so it could be enhanced in a not too cumbersome manner.. The model also doesn't have such a shiny material.. the reference even has some grungy textures...

    Of course the master of it all (bowing head to @FrankPolygon .. i'm unworthy) can easily show different approaches which end up in much beter results.

  • sacboi
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    sacboi insane polycounter

    "Avoiding unnecessary complexity will make the modeling process a lot easier and can help prevent surface flow issues and visible smoothing artifacts."

    Indeed!

    For me, a very hard lesson too learn among others.

  • count23

    Thanks for the help, this ended up beving my "current" final shape for the area in the end


    Seems to have turned out pretty good. I am using shrinkwrap to confirm any deltas in the area onto a version of the mesh without the cutout. Definitely feels easier to maintain now compared to my original approach and gave a result with no "dimples" in the shading. I'm still a little fuzzy on the appropriate constraining when extruding the loop to meet the revolved section, but that'll just be a bit of practice i guess.

    EDIT: looking at the screenshot now nad the subd cage, I may have misinterpreted the constrain axis and should have scaled X closer to 0 to keep the longitudinal rows straight, if i understand frank's explanation earlier correctly.

  • macaron10
  • dunnie

    Hi Guys .. 1st post here ... I hope I'm using the thread correctly. I'm pretty new to SubD hard surface modeling I need help with the corners of a sci-fi panel cutout. Any help would be great .. I'm getting brain meltdown deleting and redrawing edges. Anyway thanks for the noob help.


  • wirrexx
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    wirrexx ngon master


    I feel as if I have seen this post before... And Also reacted to it. Because this one Is a Deja Vu for me.

    If it's a flat surface, you can end on ngons and do whatever you want. it will not be visible.

  • dunnie


    Guys - First of all Thanks SO much for the help ... the issue is that it is on a slightly curved piece of geo ..I am going to try wirrexx's solution. Trying to keep this light because its part of a larger spaceship,

    Attatched is an OBJ of the barrel panel I am working on. Its curved so any thoughts will help.

  • AnaSuM

    Hello everyone!

    Can someone help me with this object?

    This piece makes part of the Corinthian roman column I am making. I know this should have been an easy problem to solve, but I am too dumb to figure this out.

    I want to see if it is possible to fix this instead of re-doing it.

    Thank you in advance!

    And sorry for bothering you. 😔

  • Kanni3d
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    Kanni3d ngon master

    As it's curved, you then need to have evenly spaced geometry, and plenty of it (the more you have, the more natural support loops they provide). Avoid having poles on corners, as that'd create a pinch.

  • Varravik

    Hello, I discovered this thread after tons of time spending on searching ways for my... "complex problem", just as I thought. So, one what I know, is just that I want to connect these two objects and filet their edges between their sides. I want reach exactly what @ZacD showed here in 89 page, but I don't know how do even start (how to "extract"...), which modifiers use and so on. It seems that this thread is my last hope.

  • Varravik

    Hello, I discovered this thread after tons of time spending on searching ways for my... "complex problem", just as I thought. So, one what I know, is just that I want to connect these two objects and filet their edges between their sides. I want reach exactly what @ZacD showed here, but I don't know how do even start (how to "extract"...), which modifiers use and so on. It seems that this topic is my last hope.

  • sacboi
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    sacboi insane polycounter

    @Varravik it's worth keeping in mind ZacD had shared his solution to enable 'joining' two separate objects modeled with varying number of edge segments, basically faking a smooth transition using 'floaters' (floating geometry) in order to bake detail without generating errors from a high poly mesh too low poly proxy, then to be eventually rendered out in a realtime engine.

    So I'm just wondering if your goal is to create a game asset or high resolution 3D model plus whether also relates to converting CAD/Nurbs data too polygonal?

    ___________________________________________________________________________________________________________________________________________

    @ZacD said

    "I prefer to model the "weld" as a separate floating piece of geometry."

    https://polycount.com/discussion/comment/2204079/#Comment_2204079


    @ZacD said

    "I just extract a loop of polygons that go around the cylinder, then I push one of the edges out and flatten the shape so it looks like a flat doughnut with the inner loop matching the original mesh it was extracted from, then I use a shrink wrap deformer and use it on the gun barrel. I then extrude the inner loop up, push the shape a bit so it's not intersecting, and your done. You can also model it in a way where the floating loop is connected to one of the meshes, or you can shrink wrap to both surfaces if you need to."

    https://polycount.com/discussion/comment/2204378/#Comment_2204378

    __________________________________________________________________________________________________________________________________________

    And by way of explaining terms annotated to describe each step of his tutorial i.e.

    • Extract - Duplicate cylindrical poly strip
    • Extrude - Duplicate vertices whilst still connected too original geometry
    • Delete - Delete vertical cylindrical poly segments
    • Shrinkwrap - Apply Shrinkwrap Modifier 'snapping' floating edge loops to primary curved surface
    • Extrude - Scale/push slightly, floating geometry to eliminate clipping issues
  • AnaSuM

    Well, I kinda fixed the topology by deleting and re-doing the circular part.

    Unfortunately, is very uneven, as shown in the 1st image! I will keep trying fixing it ;/



  • anishraaj

    How do I manage the mesh to get those ridges on the bucket with no pinching

  • Lemenus
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    Lemenus polycounter lvl 4
    I'm struggling modelling organic - half organic shapes. How to approach models like, for example this office chair?

  • sacboi
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    sacboi insane polycounter

    "How The F*#% Do I Model This? - Reply for help with specific shapes - (Post attempt before asking)"


    @Lemenus firstly, let us have a peek at what you've done so far?

  • FrankPolygon
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    FrankPolygon veteran polycounter

    @anishraaj Welcome to Polycount. Consider checking out the forum information and introduction thread.

    The ridges disrupt the spacing of curve's segments and this causes smoothing artifacts when subdivided. There's a few different ways to resolve these types of artifacts. Deciding which approach to use really depends on what the model will be used for and how accurate the surface needs to be.

    Compensating for unintended deformation by moving the geometry back into alignment with the curve's arc can help reduce the visibility of some smoothing artifacts but might not be able to completely resolve all of them. Using scale or shrink wrap on the highlighted edges would be a quick and easy way to achieve usable, though slightly imperfect, results with the existing mesh.

    Equalizing the segment spacing and rotating the mesh, so the ridges fall be the existing geometry in the curve, makes it easier to simplify the mesh without producing obvious smoothing artifacts. In some cases it may be necessary to adjust the position of the highlighted edges but most of the time the mesh will subdivide cleanly if the edge segments of the curve are relatively consistent.

    Increasing the number of segments in the curve will generally increase the accuracy of the subdivided surface and can help reduce smoothing artifacts but does tend to reduce the overall editability of the mesh. Deciding to place the ridges between or on top of the vertical edge segments really just depends on whether or not the added complexity helps control the shapes.

    Arbitrarily increasing the geometry density, beyond what's required to achieve clean results at the intended view distance, can be counter productive because it tends to introduce unnecessary complexity that makes it difficult to edit the mesh. It can also constrict the maximum width of edge highlights, when using the existing geometry of a curved surface as support loops for attached shapes.

    Floating geometry can also be used to add surface details without increasing mesh complexity but its use tends to be limited to high poly meshes for baking. It can also be difficult to avoid visible seams around complex shape intersections when using lots of floating elements.

    Recap: Uneven segment spacing can cause smoothing artifacts on curved surfaces. Adjusting the geometry to match the curvature when subdivided can help reduce smoothing artifacts but may not fully resolve them. Aligning the segments of curves with surface details allows the existing geometry to be used as support and can help maintain consistent segment spacing. Increasing the amount of geometry in a curved surface can increase the accuracy when subdivided but also tends to reduce the overall editability of the mesh. Evaluate how the mesh will be used and how closely it will be viewed and use an appropriate amount of geometry that subdivides cleanly and remains easy to edit.

  • wirrexx
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    wirrexx ngon master

    go Go go go Frankkky you are awesome! Love that you included Floaters!!

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