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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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  • rudenko_je
    @FrankPolygon Hello, many thanks for your help. I wouldn't think about it myself... 
    I did it according to the first option, but i got this "stretch marks". Can i fix this or is it acceptable for this element?

    UPD: so, I just need to add more faces to the cylinder?

  • IronLover64
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    IronLover64 polycounter lvl 2
    Thanks. I followed the way Arrimus3D did it, but I still have the problems with the shape when seen from above or below as shown with this line.
    You need to add another edge loop on the outside.





    Thanks. I assume the outer edge loop was added manually with the knife cut as extruding around such a circle is impossible in Blender?
  • IronLover64
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    IronLover64 polycounter lvl 2
    Catmull–Clark subdivision averages between existing points and this creates a smoothing effect. Uncontrolled subdivision smoothing tends to deform shapes and shape transitions that lack supporting geometry.

    Creating shapes that have crisp edges and minimal smoothing deformation often requires adding support loops on both sides of the edges that define shape profiles and shape transitions. Placing support loops on both sides of the defining edges will constrain the area that's being averaged out by the subdivision which tends to also reduce the associated smoothing effect.

    Supporting geometry isn't limited to just support loops either. The distance between the existing geometry in the merged shapes also has an effect on subdivision smoothing. Increasing the distance between the segments (reducing geometry density) tends to amplify the smoothing effect while reducing the distance between the segments (increasing the geometry density) tends to reduce the the smoothing effect.

    Increasing the amount of geometry in the starting primitives can make it easier to accurately merge the shapes and does tend to increase the quality of the subdivided mesh but arbitrarily adding more geometry to existing mesh doesn't guarantee an increase in overall shape accuracy.

    This is why it's generally considered best practice to match the segments of the intersecting shapes whenever possible. Matching the segments of intersecting shapes tends to produce a mesh with a more consistent geometry distribution and makes it easier to maintain the accuracy of the basic shapes. More consistent geometry density will also tend to make it easier to use the minimum amount of geometry required to hold the shapes. Which helps reduce unnecessary complexity and makes the base mesh easier to work with.

    Below is an example of what this process could look like for this particular shape. Start by evaluating the overall size of the object and the relative size of the smallest surface feature then select an appropriate number of segments for the smallest intersecting shape.

    Use primitives to preview the base of the shape intersection. Since the larger cylinder isn't constrained by adjacent geometry and the cylinder wall segments will be disrupted by the smaller shape it makes sense to adjust the number of segments in the larger cylinder to match the existing geometry in the smaller cylinder. Keeping these cylinder wall edges parallel to each other and concentric with the rest of the large cylinder's geometry will help preserve shape accuracy and reduce unwanted smoothing deformation artifacts.

    Perpendicular loops can be added to the cylinder walls to match the rest of the intersecting geometry. The segment matching doesn't have to be perfect. It just needs to be close enough that any difference between the two shapes can be taken up between the support loops around the shape intersection.

    There's a number of different ways to approach merging the shapes and adding the support loops but if the goal is to maintain shape accuracy then try to avoid disrupting the position of the cylinder wall segments. It's also important to maintain relatively consistent segment spacing on the intersecting shape but if merging stray geometry requires making a compromise it's generally better to preserve the shape of whichever feature requires the greater degree of shape accuracy.

    While there are edge cases where it makes sense to only add a support loop on one side of a shape intersection it's generally better to have support loops on both the outside and inside of most shape intersections. Placing support loops on both sides of the edges that define shape transitions will better define the area that's used to average out the smoothing and this helps constrain any deformation artifacts to smaller area.


    These same basic concepts apply to shape intersections with tapered sides and complex compound curves.


    There may also be situations where the size of the object, geometry from adjacent shapes or some other constraint makes adjusting the number of the segments in the shapes impractical. When using less than optimal amounts of starting geometry the next best option is to move or scale the geometry components along the surface of the the larger cylinder to counter act the edge stress caused by the subdivision smoothing.

    The results won't be as accurate as segment matching but when done correctly there shouldn't be any major smoothing artifacts and the result is often better than omitting minor details or having to completely rebuild major sections of a model late in the modeling process.



    Here is a comparison of the previous examples. Matching the geometry of the intersecting shape by increasing the number of segments in the larger cylinder does improve the quality of the surface but resolving the shape accuracy issues at a lower level of complexity and adding support loops to both sides of the shape intersection also help control the subdivision smoothing behavior.

    Adjusting the position of over stressed geometry to counter the deformation caused by subdivision smoothing also produces usable results but does open up the possibility of inadvertently creating other types of artifacts and is really only a good option when segment matching isn't viable.



    Segment matching is an important part of subdivision modeling and one of the keys to getting consistent results with complex shape intersections on curved surfaces. It's also important to preserve the attributes of the intersecting shapes and try to take up any differences between the intersecting geometry in the support loop around the outside of the shape intersection. This helps preserve the accuracy of the underlying shapes and will generally constrain any smoothing issues to a relative small area within the support loop.

    Below is an example of how these concepts can be applied when matching the segments of the smaller intersecting shapes to the existing geometry of the larger shape.




    Resolving smoothing artifacts caused by adding surface features to a curved mesh is an often discussed topic so there's a lot of prior art in this thread an elsewhere on the forums. The previous page has a couple of good discussions about other methods of adding holes to curved cylinders and there's been a recent discussion about holes in curved surfaces and mesh complexity. https://polycount.com/discussion/comment/2755033/#Comment_2755033

    It's also worth mentioning that subdivision modeling is an inherently approximate process. The smoothing algorithm itself is averaging things out and behaves in a fairly consistent and predictable manner. It's art not purely mathematical CAD modeling. When it comes to using overly dense or complex base meshes there's a definite point where the marginal returns start to have steep time costs.

    So there's always going to be tradeoffs between shape accuracy and modeling efficiency. This is why it's generally considered best practice to evaluate the overall size of the object, relative to the general view distance, and choose an appropriate level of mesh density based on that. Sometimes getting the desired results is about creating better geometry rather than using more geometry. https://polycount.com/discussion/comment/2746328/#Comment_2746328

    Recap:
    Match the edge segments around shape intersections.
    Use existing geometry as support for intersecting shapes whenever possible.
    Reduce unnecessary complexity by using the minimum amount of geometry required to hold the shapes.
    this worked, thanks a lot
  • Cake_Seller
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    Cake_Seller polygon
    Thanks. I assume the outer edge loop was added manually with the knife cut as extruding around such a circle is impossible in Blender?
    Yes, you are right, it was done with a knife tool. I didn't care much about topology, for sure it can be done better. It's just to illustrate how adding control loops can tighten up geometry when used with a subdivision surface modifier.
  • deezOrange
    I have been getting some annoying pinching 


    This is the shape I set out to achieve 
    this is what I'm getting 
    I would also like it to be flush with the curved surface 
    if someone has a way to fix this or has any solution to re-model this that would be great because I've tried everything I know and all the results have been crappy. I've tried increasing the poly count and trying it like that but it made it hard to model other parts of the model. So please if you got ANY solution please tell me. Thanks :)
  • Cake_Seller
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    Cake_Seller polygon
    I have been getting some annoying pinching 
    Hi, not sure that I understand what exactly you want to achieve. Could you please provide a blend file with two initial shapes (before you try to boolean one out of another)?
  • sacboi
  • marcstigall
    I'm having trouble with modeling a pillow from a tutorial on youtube. This one to be exact.

    I take a cube and scale it down the z to 0.03. In edit mode, I give it 30 cuts on each side and one going around. I add cloth physics with the silk preset. After tweaking the settings like the tutorial and adding a force object for the simulation, the cube just collapses on itself. When the cube is scaled up it blows away almost. I don't know why this is happening. Here are some photos.




  • sacboi
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    sacboi insane polycounter
    Worked for me?!


    Sims can be tricky, an incorrect setting or missed step will often throw the whole thing out of wack.

    Anyway simple fix, just scrub through next time around double checking each stage, before moving on.

  • marcstigall
    @sacboi Thank you for the tip. I will take a look at it again and see if anything changes
  • IronLover64
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    IronLover64 polycounter lvl 2


    Is there a better way to make a 180 degree pipe intersection? My attempt was just merging the two mesh together in boolean, but the intersection topology isn't good as well as the sharp corners.
  • ZHCX520
    Who knows how to model this faucet
  • wirrexx
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    wirrexx ngon master


    Is there a better way to make a 180 degree pipe intersection? My attempt was just merging the two mesh together in boolean, but the intersection topology isn't good as well as the sharp corners.

    Bear with me, I'm really new to Blender so trying my best.
    But, the easiest and fastest way, is just like you're doing it. Fewer.
    Step one, two similar pipes. Make sure that they align.
    step two, Boolean, Union. Clean up wherever it messes up.
    step three. Add the support loops.
    step four. Subdivide/Turbosmooth.
    Sides on the cylinder 6-8 sides. Match them up. And add the support loops.


  • IronLover64
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    IronLover64 polycounter lvl 2
    wirrexx said:


    Is there a better way to make a 180 degree pipe intersection? My attempt was just merging the two mesh together in boolean, but the intersection topology isn't good as well as the sharp corners.

    Bear with me, I'm really new to Blender so trying my best.
    But, the easiest and fastest way, is just like you're doing it. Fewer.
    Step one, two similar pipes. Make sure that they align.
    step two, Boolean, Union. Clean up wherever it messes up.
    step three. Add the support loops.
    step four. Subdivide/Turbosmooth.
    Sides on the cylinder 6-8 sides. Match them up. And add the support loops.


    Thanks a lot!
  • Cake_Seller
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    Cake_Seller polygon

    Is there a better way to make a 180 degree pipe intersection? My attempt was just merging the two mesh together in boolean, but the intersection topology isn't good as well as the sharp corners.
    You can also use Add Mesh: Extra Objects Blender addon. It can save you some time. It's an addon that is shipped with Blender.


  • JackofSpades261
    Since we're on pipes/cylinders, I'm modelling after a reference that calls for the pipes to be at this angle, and I've connected them in a way I thought makes sense, but it creates a shading issue that I can't seem to fix. Here's the issue with wireframe and a mocap material to hopefully show it off better
    I tried adding some very close edge loops to "constrain" the problem, and while it does fix the issue, I was wondering if there's a way to make the joint look more... natural:
    I've checked all the pipe tutorials I could find, but none of them cover cylinders being connected at this angle, always 90 or 45 degree connections.
  • Cake_Seller
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    Cake_Seller polygon
    Since we're on pipes/cylinders, I'm modelling after a reference that calls for the pipes to be at this angle, and I've connected them in a way I thought makes sense, but it creates a shading issue that I can't seem to fix. Here's the issue with wireframe and a mocap material to hopefully show it off better
    Hi, maybe a good way to make this pipe more appealing is something like this?






  • JackofSpades261
    Since we're on pipes/cylinders, I'm modelling after a reference that calls for the pipes to be at this angle, and I've connected them in a way I thought makes sense, but it creates a shading issue that I can't seem to fix. Here's the issue with wireframe and a mocap material to hopefully show it off better
    Hi, maybe a good way to make this pipe more appealing is something like this?
    I don't know why it didn't occur to me to try a flat surface. The reference I'm using also isn't very clear on this pipe section, so I'm sure it also won't be an issue as well. Thanks!

  • IronLover64
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    IronLover64 polycounter lvl 2
    I'm trying to model this radar antenna thing and while I have the base mesh prepared, the reference has the mesh hollowed wither certain faces on certain areas. I tried to make them with loop cuts, but they ruin the silhouette and shape of the mesh. Is there a better way?
  • Thanez
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    Thanez interpolator
    I'm trying to model this radar antenna thing and while I have the base mesh prepared, the reference has the mesh hollowed wither certain faces on certain areas. I tried to make them with loop cuts, but they ruin the silhouette and shape of the mesh. Is there a better way?
    Hey bud. I'm guessing it's also those ribs on the inside giving you trouble, so I included those here.
    One way to tackle this is to model it flat and straight, then bend it into the shape you want. 
    Note that I didn't take the skewed part of it into consideration, nor the details at the top. I'm only trying to show you how to get the details in without messing with the curve. The important thing is that the curve needs a consistent amount and spacing of edges, or it will end up wonky like your result.

    I want the wall thickness at 1mm and edgeloops at 1mm, so I start with a plane that's 38mm long, and with (Length-1=37) lines going through it. That leaves me with 1mm strips.


    -----
    If you want the entire thing to have a skewed thickness like your ref, this is the time to add it in. I didn't add it in and it won't be shown. For 3ds max, a soft ramp FFD is all that's needed.
    -----

    Then I plan to have a 1mm "ceiling" and "floor", so I add those in.


    Then I want the internal strips to end 2mm above the floor, so I add that in, and their supporting edgeloops.


    The point is to get this selection of polygons ready. This is the surrounding structure and the ribs within, all with 1mm edgeloops ready to go.


    I shell that plane by 1mm to generate a back wall, then extrude those polygons by however much I want.


    Two symmetry modifiers later and I have my final shape


    One bend modifier later and I have the final shape.


    Turbosmoothed isoline




    Closeup



  • IronLover64
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    IronLover64 polycounter lvl 2
    Thanez said:
    I'm trying to model this radar antenna thing and while I have the base mesh prepared, the reference has the mesh hollowed wither certain faces on certain areas. I tried to make them with loop cuts, but they ruin the silhouette and shape of the mesh. Is there a better way?
    Hey bud. I'm guessing it's also those ribs on the inside giving you trouble, so I included those here.
    One way to tackle this is to model it flat and straight, then bend it into the shape you want. 
    Note that I didn't take the skewed part of it into consideration, nor the details at the top. I'm only trying to show you how to get the details in without messing with the curve. The important thing is that the curve needs a consistent amount and spacing of edges, or it will end up wonky like your result.

    I want the wall thickness at 1mm and edgeloops at 1mm, so I start with a plane that's 38mm long, and with (Length-1=37) lines going through it. That leaves me with 1mm strips.


    -----
    If you want the entire thing to have a skewed thickness like your ref, this is the time to add it in. I didn't add it in and it won't be shown. For 3ds max, a soft ramp FFD is all that's needed.
    -----

    Then I plan to have a 1mm "ceiling" and "floor", so I add those in.


    Then I want the internal strips to end 2mm above the floor, so I add that in, and their supporting edgeloops.


    The point is to get this selection of polygons ready. This is the surrounding structure and the ribs within, all with 1mm edgeloops ready to go.


    I shell that plane by 1mm to generate a back wall, then extrude those polygons by however much I want.


    Two symmetry modifiers later and I have my final shape


    One bend modifier later and I have the final shape.


    Turbosmoothed isoline




    Closeup



    Thanks a lot. The radar part also has sloped sides that are difficult to create with a flat straight model. I used booleans to create the slopes on my attempt, but it doesn't seem like it would work well in your example. What do you suggest?
  • SnowInChina
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    SnowInChina interpolator
    for exact form, you might want to use a follow crve modifier and mirror it to the other side
  • IronLover64
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    IronLover64 polycounter lvl 2
    Incredible! Thank you so much!
  • 2300511685
    HI  I don't know how to deal with the line here. There are protruding things on this surface and a hole in the bending position. Is there any good way? Please help me.

     HI
  • sacboi
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    sacboi insane polycounter
    Depends...

    For example, if you're planning to model those details out as part of a game asset creation process, then look into 'floaters' (Floating Geometry) otherwise search optimized hard surface or gun modeling techniques, there'll be options aplenty too choose from.
  • Mir76
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    Mir76 polycounter lvl 3
    EDIT : you can delete this post. I found a solution. So sorry.
  • Eric Chadwick

    The best thing to do in this situation is to post your solution! Share with the community. There are likely to be others in a similar situation, and your solution will be appreciated.
  • count23
    Hi folks,

    I'm trying to model this shape in SUBD: 

    Everything is fine, except this intersection here, you can see it's warping and causing shading issues:

    I'm not quite sure how to fix this, i've tried modifiers, i've tried destructive. All i can figure is if i want the shape of the flat cutout off a circle that's going into a rounded shape, i may simply have to freeze the subd first, then extrude inwards and bevel last. Is it as simple as an order of operations or is tehre a topology issue here i'm not seeing?

  • IronLover64
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    IronLover64 polycounter lvl 2
    Now that I got the shape right, how do I get the end to bend like this with such dense geometry?
  • Cake_Seller
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    Cake_Seller polygon
    Now that I got the shape right, how do I get the end to bend like this with such dense geometry?
    You can try to increase resolution of Lattice and then deform it:





    After I press R to rotate the lattice vertices, I press Z to rotate only along the Z-axis. Unfortunately, the ScreenCast Keys addon does not register those keystrokes.
  • IronLover64
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    IronLover64 polycounter lvl 2
    Thanks. But using a second lattice doesn't work too well as it warps a part of it in a bad way and reducing it to a single lattice or rearranging the lattices don't help. I there another way?
  • IronLover64
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    IronLover64 polycounter lvl 2
    After asking a friend, I finally found a solution:
    -Apply the lattices that makes the end thinner and the one that bends the end
    -Choose a face that is rotated at a good angle before the rotations start falling apart
    -Add a transform orientation for the face on the top middle
    -Select an edge on the bottom loop if you have more loops
    -Make a face from that (lock the axis to X or Y when editing so the face`s orientation is consistent to that of the edge, which is where the transform orientation comes in handy)
    -Select the verts that come after that edge
    -Turn on snapping for face, set to active, and turn on project individual elements
    -Set the transform orientation to global
    -Go in orthographic top view
    -Snap the verts to the face on the Z vertical axis (Z in Blender and Y in other software)
    -Repeat the same steps for each loop
    -Done

  • Cake_Seller
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    Cake_Seller polygon
    After asking a friend, I finally found a solution
    Nice 👍. Good luck with the rest of the project!
  • EarlGreyLatte
    Hello! I am still learning 3d Modeling. Since I model for 3d printing I have been using Booleans to make most of the details. I am trying to learn how to model them more 'properly' but I am having trouble  maintaining the over all curves of the piece I am adding the details too. 

    The first picture is the lowest LOD and the second one is me trying to figure it out but its getting really messy and starting to lose the curve. The blue piece is one of the original Booleans. I work in Maya, All and any advice is appreciated!


  • sacboi
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    sacboi insane polycounter
    If you're thinking of printing this, then I'd suggest a Shrinkwrap option in Maya under the Deform menu or just simply boolean / manually edit those insets correctly on a curved surface as previously illustrated a few pages back:


  • IronLover64
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    IronLover64 polycounter lvl 2

    I'm trying to make the hinge on my model of these tank tracks. I followed a 3DS Max tutorial and tried doing it in Blender. the results were not good. Is there a better way to do this in Blender?
  • IronLover64
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    IronLover64 polycounter lvl 2
    Update: I successfully created the shape I wanted, but because this will be duplicated many times over, it is too high poly for my PC to handle. Is there are more efficient way to make a tank track like this? 
  • Cake_Seller
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    Cake_Seller polygon
    Update: I successfully created the shape I wanted, but because this will be duplicated many times over, it is too high poly for my PC to handle. Is there are more efficient way to make a tank track like this? 
    Here are couple of ways you can optimize performance:
    • Instead of making duplicates of track pieces try to Duplicate Linked. Use Alt + D combination instead of Shift + D. When you use Duplicate Linked you are not making copies of mesh. Instead, you are using the same mesh in many objects. That should save you some RAM.
    • In Subdivion surface modifier of a Track object reduce number of Levels Viewport to 0. In that way you are not gonna show subdivision modifier in the viewport, only on render.
    • Probably in the viewport you don't need to render all the track objects. Try turning it off by toggling this button:

      To activate this button you need to go to the Filter menu:

    • After all these tweaks try make a test render of your scene. Cause I suppose even if your scene shows fine in viewport doesn't mean you'll be able to render it (cause it does a different kind of calculations).
    • If after all these are done your computer still can not handle that much of geometry then probably you need to create low poly version of a track. When 2 subdivision levels applied to a piece of track it has 109,632 triangles, that's way to high. Even if we disable sub-d it has 6,852 tris. Taking into account that you need possibly a hundred of those pieces that is quite high.
    What CPU/GPU, how many RAM are you using?
  • Daf57
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    Daf57 polycounter lvl 8
    The lower leg on this mech is giving me fits - any ideas how to approach?

  • Cake_Seller
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    Cake_Seller polygon
    Daf57 said:
    Nevermind - will work it out. ;)
    Could you please share your solution? I'm really curious. I'm learning 3D and yesterday I saw your post and tried to model myself the piece you had problems with and I also found it very tricky.
    Here is what I come up with:


    The steps I've done:
    1. Make base shape with Subdivision surface (level 3; maybe level 2 is good enough though).
    2. Apply Subdivision surface modifier to have denser topology.
    3. Then add a plane and create shape that we gonna you to make a cut. Like this:


    4. Make an Intersect (Knife) cut. We gonna receive this:

    5. Mirror:

    6. Clean up topology a bit:

    7. Delete faces below the edge:

    8. Add missing geometry:

    9. Add control loops around edge (using Bevel Ctrl + B):

    10. Add Subdivision and Solidify modifiers:


    It is a bit messy and requires a further cleanup but probably a good starting point.

    What do you think about this solution? Maybe you found a better one? I would appreciate it if you share.
    For those who might be interested I was trying to model this part:


  • PolyDoge
    Hello, how could I delete that pinching? 







    I have read other solutions with cylinders in this thread and generally recommend to generate more geometry, the problem is that in this case I think that both cylinders would have to double maybe triple edges to have the support loop that is required to eliminate that pinching, and I think that would make me quite difficult to model the rest of the object.
  • IronLover64
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    IronLover64 polycounter lvl 2
    Update: I successfully created the shape I wanted, but because this will be duplicated many times over, it is too high poly for my PC to handle. Is there are more efficient way to make a tank track like this? 
    Here are couple of ways you can optimize performance:
    • Instead of making duplicates of track pieces try to Duplicate Linked. Use Alt + D combination instead of Shift + D. When you use Duplicate Linked you are not making copies of mesh. Instead, you are using the same mesh in many objects. That should save you some RAM.
    • In Subdivion surface modifier of a Track object reduce number of Levels Viewport to 0. In that way you are not gonna show subdivision modifier in the viewport, only on render.
    • Probably in the viewport you don't need to render all the track objects. Try turning it off by toggling this button:

      To activate this button you need to go to the Filter menu:

    • After all these tweaks try make a test render of your scene. Cause I suppose even if your scene shows fine in viewport doesn't mean you'll be able to render it (cause it does a different kind of calculations).
    • If after all these are done your computer still can not handle that much of geometry then probably you need to create low poly version of a track. When 2 subdivision levels applied to a piece of track it has 109,632 triangles, that's way to high. Even if we disable sub-d it has 6,852 tris. Taking into account that you need possibly a hundred of those pieces that is quite high.
    What CPU/GPU, how many RAM are you using?

    Intel Core i5-7500, EVGA GeForce RTX 2060 SUPER 8 GB SC, 16gb ram
  • IronLover64
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    IronLover64 polycounter lvl 2
    and I wanted to ask about the optimization of the geometry itself, because I will be rigging the tank
  • IronLover64
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    IronLover64 polycounter lvl 2
  • Cake_Seller
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    Cake_Seller polygon

    Intel Core i5-7500, EVGA GeForce RTX 2060 SUPER 8 GB SC, 16gb ram
    Of course, when it comes to rendering the more power you have is the better, but your specs are quite decent IMO.
    and I wanted to ask about the optimization of the geometry itself, because I will be rigging the tank
    Hm... Are we still talking about the tank tracks? Cause I don't understand what relation track geometry optimization has to rigging.

    Here I created two low poly versions on track using boolean workflow:


    Geomtery:

    The version with bevels has some small issues with shading, but they are not gonna be noticeable unless you zoom quite close.

    It all depends on how close you gonna show tracks on render. If not really close then maybe geometry can be simplified even more. If you want to show tracks pretty close, then maybe you want to use the version of track with Subdivision surface modifier for those pieces that are close and low poly version for pieces that are further from the camera.

    You can check out the low poly versions I created in the attachment.
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