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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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  • Cake_Seller
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    Cake_Seller polygon

    @Aurock

    The only solution I've found is to use a boolean cut, but it seems like a lot of work

    Most probably this is the way to go. Pretty sure this is the best solution Blender has out of the box. Maybe there is some fancy addon to speed up the process, but unfortunately, I didn't hear about it.

  • KebabEmperor
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    KebabEmperor polycounter lvl 3

    @Aurock IMO Blender bevels are a little bit wonky but here are some options:


    You can use bevel weight, But bevel weight works weirdly.


    Or you can use 'percentage' option under the bevel modifier:













    This might or might not help with your problem, I am not sure about that but might be useful somehow ;--;

    And yeah boolean seems like the only way for that.



    (I messed the text up it's 1am here sorry 😵 )

  • sacboi
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    sacboi high dynamic range

    Aurock said:

    Hi all, CAD guy here learning some Blender.

    Is there a nice way to have two circular bevels of different sizes meet and intersect in such a way that circularity is preserved? As in this CAD image below:


    At this point, trying too create a 'workable' variable radius Bevel natively in Blender is, I'd agree as KebabEmperor mentioned a little bit wonked, although on the other hand Meshmachine:

    AFAIK would be another possible approach. Outputting results similar too CAD like fillets but of course its' obviously dependent on a given use case. That said however, I'm still of an opinion that a vanilla solution can be beneficial in terms of an 'out-the-box-workflow' without necessarily reliance upon third party tools, per se...

    By the way Gleb, over at Blender Nerds, wrote up a series of walkthroughs I'd bookmarked which similarly implements weights and percentages so at the very least maybe worth a look, as well.


  • Aurock
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    Aurock polycounter lvl 9

    Thanks for the info all! I'll check out the video and the variable rounds stuff, good to know I'm not missing something obvious though.

  • ColMatrix

    Hi all,


    pretty cool thread! I really appreciate your guidance/recommendations. I will try to be brief.


    I wish to model a Rack and Pinion, I am confident with the modeling, the problem is, I will be creating this for Virtual Reality. I cannot model all the teeth, as the asset can be very long, plus the rack and pinion is maybe 5% of the overal asset. The user will be able to interact with the rack segments (assembly: installing onto other racks).


    My thoughts, simple 6 faced rectangle to represent the rack with textures including normal map - I am concerned the normal map will be too unrealistic given the depth difference.


    Better approach?


    The asset can be seen close up, even with a cog animating along the rack. End device Occulus Quest 2 using Unity. Normal maps allowed.


    Many thanks

  • Kanni3d
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    Kanni3d ngon master

    @ColMatrix Context of the game, surrounding environment, remaining drawcall/geo budget and overhead will really dictate your art direction for this. I think the safest and most realistic solution is that this could be handled with a really nice bake + supplemental bake overlays into the textures (AO/Cavities etc) to really push its depth.

    VR/Quest 1&2 are relatively low spec and geo gets rendered twice (once per eye). 15k triangle cog is actually as performant as 30k effectively.

  • ColMatrix

    Hello Kanni3d, thanks for taking the time to respond. Do you have an example of how the maps could look like? I am familiar with the standard, AO, and Normal maps am unsure if using these maps are enough.

    I have never used a normal map for such a component (Will test with Substance 3D), normally on a larger surface where the details are much smaller and can be bevelled. Here, there wont be much of a viewing angle, before geometry between the teeth is seen, which obviously shouldn't exist.



    Thanks once again

  • Rosx

    Hi guys, first post here! Btw very cool and useful thread!

    I got some topo problems in one small part of a button i made (discovered thanks to the bad shading after applying sub-d modifier) caused by lacking of quads.

    Could you guys please guide me through this topo problem? Which should be the right topo on that small part?😁

    Thanks in advance

  • wirrexx
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    wirrexx ngon master

    consistency in the edges is causing the pinch. I would recommend just to go back 1-3 pages, It's explained more than once.



  • Rosx
  • Kanni3d
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    Kanni3d ngon master

    Sorry for the late reply. You basically have two situations when you are in the circumstance baking this much silhouette deviation/detail onto something so simple. If you bake with your lowpoly currently as is, you'll retain the volume, but have tons of ray misses, which will appear black/artifacty - may look passable at a distance, but as something really up close - it probably wouldn't sell the illusion very well.

    If you bake with the most forward facing polygon to be at the base of the details - you'll have little to no ray miss errors, but far less volume. Overlaying a lot of the baked maps (curvature and ao) will help here as mentioned, as you really have to push depth with additional texturework since the bakes can only do much.


    Pick your poison, pro's and cons - both are best for certain scenarios. If you are forced to have this sort of detail to be very large and close to the players face, consider some more geo, but still while being conservative with it as its VR. You mentioned this thing is only 5% of the entire asset, it probably wouldn't warrant this much detail and geometry, I'd go with the latter solution and call it a day for only 5% of details.

  • ColMatrix

    @Kanni3d Thanks for your assistance and recommendations. I will give it a go 😁


    Have a good one!


    Cheers

  • tester1225
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    tester1225 polycounter lvl 6

    How would you guys approach a roof like this, if I also wanted to extrude the trim lines from the same geo, on all sides? I'd really prefer a polygonal modelling way LOL, as I just find controlling curves in maya so finicky it's unreal! But as you can see the blockout attempt - the curvature really isn't that smooth and it stands out up close.

  • perprerp
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    perprerp triangle

    Can mods make me automatically upvote @FrankPolygon 's posts please because I'm getting fed up clicking the tny button every time, it makes no sense

  • sacboi
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    sacboi high dynamic range

    Probably, a better place to raise an issue with the new text editor...aside from prompting an ADMIN response in a timely manner, is here:

    although I've had a not too dissimilar train of thought, in terms of a slightly more effective method other than showing ones support by merely 'button mashing'?!

  • Eric Chadwick

    Maybe @FrankPolygon just needs a tip jar.

  • sacboi
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    sacboi high dynamic range
  • KebabEmperor
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    KebabEmperor polycounter lvl 3

    @Eric Chadwick A t-shirt with 'frankpolygon on polycount' text would be nice for the store

  • FrankPolygon
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    FrankPolygon grand marshal polycounter

    Really appreciate the support but also need to acknowledge that a lot of artists have contributed to this thread over the years. Think the best way to honor that is for the discussion here to remain focused on the community coming together to provide feedback for modeling and topology questions.

    Personally, the +Greentooth button seems like an appropriate way to thank someone or highlight a post without having to add a two or three word reply.

  • rogi92
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    rogi92 polycounter lvl 3

    Hello guys,

    Blender user here.

    I absolutely can not get the idea how to make this one. What is your type guys to make this molecular sphere?

    Thank you.


  • SnowInChina
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    SnowInChina interpolator


    ps: next time post your attempts first

  • wirrexx
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    wirrexx ngon master

    I dont think you can create a perfect Hexagone sphere. @SnowInChina example is the way to go though!

    So shift+A and use an ICO sphere and subd. Once.


    apply modifier and select one vertics in the middle of the hexagon and shift+g = amount of adjacent faces. And delete those. Now repeat for all the unwanted vertices. remember, only one vertices is enough to select.



  • SnowInChina
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    SnowInChina interpolator

    as far as i know its mathematical not possible to create a perfect hexagone sphere

    and for blender there`s an addon called geodesic domes which can create a lot of different base topologies

  • rogi92
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    rogi92 polycounter lvl 3

    Thank you so much for this man, also wirrexx.

    Thanks guys : )

  • LouisMarshall

    I am creating a 3d model from a first person video game. Everything has been going smooth until I got to working on creating cuts into the cylindrical body of the model. I am looking to use a high poly to low poly workflow and currently I am using the chamfer modifier to add support loops to the cut out shape. I have managed to get the general shape of the cylinder cut down but I am stuck at adding the correct topology for the top inside angles. I will provide some screenshots below.

    Edges I am having trouble with:

    High poly:

    I need the top edges to be supported so that they wont collapse with the high poly version. If anyone has any idea how to get around this it would be a great help.

  • FrankPolygon
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    FrankPolygon grand marshal polycounter

    @LouisMarshall There's a few different topology strategies for sharpening those corners while also minimizing the visibility of any smoothing artifacts. Which approach makes the most sense will depend on how accurate the shapes need to be, how visible the area is and how much time was spent creating the rest of the model.

    If the subtracted shape is relatively small or won't spend a lot of time in-front of the player then the easiest solution would be to use the existing geometry and adjust the topology routing so the adjacent edges create a support loop that flows around the outside of the shape intersection. After the topology flow is resolved it should be possible to select the edges of the shapes and bevel to add support loops. The bevels in the corner can be resolved to flattened diamond shaped quads that connect to the geometry of the underlying curve.

    Vertices at the top of the inside corners may need to be moved downward to compensate for the smoothing stress when the subdivision is applied. Using the existing geometry of the curved surface as the outer support loop and using the transitional area between the loops to make up the difference between the shapes should prevent the corner support loops from running out into the adjacent shape and causing undesired deformation when subdivision is applied.

    Here's an example of what this process and topology layout could look like.

    If more shape accuracy is required then it may be necessary to increase the geometry density of the underlying curve before subtracting the shape. Adjust the number of segments in the curved surface until the corners of the intersecting geometry lands between a shared set of edges. These radial edges in the curve can then be used as support loops that tie into the corners of the subtracted shape.

    Adjust the topology so the edges that run across the curved surface act as outer support loops for the shape intersection. Add the rest of the support loops around the shapes using a bevel operation and merge down any stray geometry to the outside support loop on the curved shape. Join through or add support loops as required. Any difference between the curved surface and the subtracted shape should be taken up by the outer support loop. This will help constrain any potential smoothing deformation to a smaller area. Which will help minimize any potential smoothing artifacts.

    Here's an example of what this process and topology layout could look like.

    In subdivision modeling, it's generally considered best practice to use the existing geometry of the intersecting shapes as support loops and to try and resolve most of the topology flow issues at the lowest possible level by matching the segments of adjacent shapes. Both of the topology strategies shown above take advantage of the existing geometry in the curve. The only major difference between these two strategies is whether the support loops for the corners need to end on the existing geometry of the curved surfaces or whether these support loops can run out into the existing geometry of the curved surface.

    Here's a close up comparison of the topology layouts and the subdivision previews. Both topology strategies should be viable at intermediate view distances. The subtle difference in surface quality really isn't all that noticeable unless the player is viewing the model in an extreme close up. So whether or not it makes sense to add in all of that extra geometry really comes down to how the model will be used and whether the tradeoff in modeling efficiency is worth the slight loss of surface quality.

    Recap:

    • Solve topology flow issues at the lowest level possible.
    • Match the segments of intersecting shapes when possible.
    • Use the existing geometry as support for shape intersections.
    • Route the topology flow around the perimeter of the intersecting shapes.
    • Consider the viewpoint and make tradeoffs between accuracy and efficiency when appropriate.
  • LouisMarshall
  • LouisMarshall

    Hello @FrankPolygon,

    Thanks a lot for taking the time to view my post, I have been struggling with this problem for a few days now. The 3D model that I am creating will not be very close to the player so the first example from your post will work the best here. I have attempted to replicate what you had show and have managed to create this so far:

    This a so much better than what I previously had but I am now getting a slight distortion from the cylinder faces that are adjacent to the diamond shaped quads of the cut out shape geometry. I have shown this in the third image with the red arrows. I turned on the isoline display within the turbosmooth modifier settings to compare my result with your examples and I notice that the outer edges from the existing geometry from the cylinder are much further away from the cut out shape edges than you have on your images. I have pointed to this with the green arrow in the second image. Is this causing the distortion?

    In the third paragraph in your reply you mentioned: 'Vertices at the top of the inside corners may need to be moved downward to compensate for the smoothing stress when the subdivision is applied.' Is this the fix that helps with the distortion problem that I am getting? Could you explain what you did here if so? Sorry if this is annoying, I am new to modelling so my brain is still slow to how to fix these types of problems. Thanks for taking the time to write the previous response again.

  • FrankPolygon
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    FrankPolygon grand marshal polycounter

    @LouisMarshall Glad the post was helpful.

    When trying to minimize smoothing based subdivision artifacts, like pinching and stretching, there's two basic strategies that tend to work well with existing geometry: averaging out the differences between the shapes over a wider [preferably flatter] area or constraining the difference between the shapes to the narrow transitional areas around the shape intersections.

    Constraining any changes in the larger shapes to the smaller loops around the transition areas should help minimize the visibility of any minor smoothing artifacts. Even when viewed from glancing angles. Here's an example of what the smoothing should look like when properly supported.

    Moving the top vertices downwards just helps relieve some of the pinching in the corners by proving a bit more space for the new geometry.

    The distance between two adjacent support loops will determine whether the smoothing stresses on the connecting edges will introduce pinching or smoothing artifacts. Too close together and the loops will cause pinching. Too far apart and the loops will cause stretching. So the observation about the distance between the support loops being a contributing factor to the new smoothing artifacts is correct.

    Placing an additional support loop on both sides of the shape intersection will even out the mesh density and help prevent this type of stretching artifact when the subdivision is applied. The example below shows how these additional support loops may be necessary to support shape intersections that occur in the middle of longer shapes.

    Sharp shading the mesh in the subdivision previews creates facets that should make the stretching artifacts a bit easier to see.

    Different topology layouts are also susceptible to this type of stretching artifact. It's just that the higher density makes it a bit less obvious at this scale.

    Curved surfaces tend to be a bit more sensitive to abrupt changes in topology. So it's often helpful to route support loops in a way that produces fairly consistent results when the mesh is subdivided. It's also important to try and maintain the accuracy of the underlying shapes over as much of the surface as possible. Once the geometry along a curve moves out of plane with the surface it's a real pain to try and bring everything back into line manually.

  • LouisMarshall

    Thanks for explaining this further for me. I have managed to remove the artifacting with this help that you have provided.

    Here is the look of the section now:

    There is only minor stretching towards the corners but this section of the model won't be close to the player so it will be fine. Thanks again for taking the time to overlook this for me.

  • wirrexx
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    wirrexx ngon master

    could also do it this way if you want. Less pinching and issues =)

  • X756313735

    Can someone please help me with this.

    Thank you for your time 

  • wirrexx
  • X756313735
  • Alex13
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    Alex13 polycounter lvl 4

    Hi, please could anybody advise.

    I have two issues on my model. Problem 1 can be seen in the 1st 3 pictures where i'm getting some picning once Turbo is applied.

    I'm struggling to terminate these polgons on my lowpoly so that when a turbosmooth is applied i don't get pinching throughout the model.

    I know this isn't a tough problem but i'm on the tailend of covid and am modelling in a fugue state If anyone could do a quick paint over of a suggested flow I would be very greatful.

    Thanks!

    Problem 2:

    I've been a long time out the hard surface vehicle game, I have a hinge from edge vent coming out of the side and havn't found any good reference for how to support this to stop pinching also

    I've looked at sports car topology but havn't found anything that is clear to me.


    The full model as it is, you can see the probelm areas i'm suffering with. Any other critiques are welcome too.


  • wirrexx
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    wirrexx ngon master

    On the first 3 pictures.

    1. when its not an perfect flat area. This issue will appear.
    2. Add a edgeloop here and see if this helps your issue.


  • Alex13
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    Alex13 polycounter lvl 4

    Thanks, I used make planar and used an inset on the faces and came up with this result, adding in some supports to bring the poles in seemed to be solution.


    Problem 2 has been solved too I think


    my issue was also caused in part by using double turbo smooth,

    Topo changes below in case ever helps anyone else - picture before turbo


  • IronLover64
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    IronLover64 polycounter lvl 2

    How do I make this upside down T shaped cutout in my model? Boolean doesn't seem to be a good solution based on the topology


  • wirrexx
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    wirrexx ngon master

    If you are doing a Subd and lp for it later to bake on, consider floaters. Either that or subd your mesh (the oval) and have enough geo to just select the faces of a T and intrude. Here's some dirty fast "you know what I mean" designs.


    _____________________________________________or___________________________________________________________________________________________________


  • Elmo_Learning

    Thank you everyone who shared their problems

    Thanks a ton to all those who took time to clarify the root cause of majority of issues and possible solution to take on.

    It took me 3 days straight with some nap in between to read everything from page1(Sep 2008).

    It's totally worth it to read everything and make notes on stuff you can relate to. Only regret I had is I didn't found perma account and links related like dropbox are dead.

    Now, I think there are phases in modelling from which everyone has to go! I won't make any perfectionist excuse and will work harder everyday!

    Once again thank you everyone!

  • HAWK12HT
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    HAWK12HT polycounter lvl 12

    Glad that someone finally went through page 1 like me with all those years of gold mine info. I do hope you saved the images along the way :D

  • hanabirano
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    hanabirano polycounter lvl 4

    I strongly suggested you do it using Wayback Machine, there is a lot of golden gems that are now hidden 😉

  • Elmo_Learning

    Wow I didn't knew about this. I saw some pictures and profile that was hidden before! +_+

    Will go one more round next month I guess since I have captured most of text via screenshot and have to transfer digital knowledge to physical notebook ( writing it down ) so I can refer whenever I'm stuck or daydreaming. haha!

    I envy you guys, you all are far more better than me and a lot younger too. All the best with journey :)

  • GlowingPotato
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    GlowingPotato polycounter lvl 10

    Hi!

    is this the case where I need to add more geo to have a correct SUBD without pinching ?

    I'm having a hard time figuring out how to place support loops around this indent to have a correct subD model.

    I made the low poly object like this.

    Now I'm trying to build the hi-poly from it and my subD skills suck.

    Can you point me how to correct place support loops around this indent ?


    EDIT:

    i did this

    and after SUBD:

    is this the correct approach ?:

  • sacboi
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    sacboi high dynamic range

    Looks fine to me!

    Typically when either applying tris or indeed ngons to resolve artifacting, best results are usually derived via planar surfaces - as in your example.

    Although in most situations, when curvature is introduced to a given shape/object, an issue may invaribly arise.

  • wirrexx
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    wirrexx ngon master

    You could always cut the geometry inbetween existing geo. this way you have natural chamfers around your mesh ( you could also select the faces and inset them) .


    here is a really really really lazy me doing this in gif, because at work, I have not been doing 3D for a loooong ass time.


  • GlowingPotato
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    GlowingPotato polycounter lvl 10

    @sacboi thanks for your input! but after close inspecting, i have pinching!! =/

    @wirrexx thanks A LOT for taking the time to make this .gif and sharing your workflow. But I may have done something wrong, i still have a little bit of pinching and the curve around the corner doesn't look symmetrical on my model. But i'll try again.

  • wirrexx
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    wirrexx ngon master

    the higher density your base mesh is, the less pinch you will see. however. if it's barely visible and you are going to bake down and texture it. The pinch will in the end not really show =)

  • sacboi
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    sacboi high dynamic range

    Agreed!

    Plus I think would also depend upon, if the model is viewed up close ingame i.e. animated rather than for example, a portfolio still or such like...

  • Kanni3d
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    Kanni3d ngon master


    Additionally from the previous advice, try terminating your support loop where your model becomes more planar/flat. If you're putting a triangle/junction on a curved area/too soon of a termination - it'll pinch due to the pole.



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