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Flattening tires where the rubber meets the road

john_antkowiakjohn_antkowiak Posts: 334
in New Users

Hi. I've just spent an hour scrolling through forum posts about tires. I'm sure this has been asked., but I can't find an answer. I've been dissatisfied in other renders as well. To me, it looks like the car in my image is almost floating, like it has zero weight. I tried setting the road plane as a collision item of the car and adjusting its parameters, but nothing changed the outcome in any way. I don't want the tires to look flat, only functional. I also tried sinking the car beneath the plane, but because of their geometry, you couldn't tell they were sunk at all until it looked unnatural.

There's gotta be a trick for this... right?

And yes, I know... I should have turned the wheels before rendering. There's always something :P

Penguin.jpg
2000 x 1236 - 2M

Comments

  • JVRendererJVRenderer Posts: 661

    You can use Meshgrabber to deform the tires slightly

  • Sven DullahSven Dullah Posts: 7,621

    Or Dformers

  • john_antkowiakjohn_antkowiak Posts: 334

    Thank you for the suggestions. I couldn't get the hang of Meshgrabber some time back but I may not have worked hard enough at it. I do know the basics of Dformers. As far as I can tell, they don't adjust for volume - in other words, they will flatten the bottom of the tires (the same as sinking the car below the plane) but I'd have to bulge the sides myself. My results have been less than pleasing so far. I was sure there must be car guys who overcame this problem years ago.... am I wrong? Would Meshgrabber do anything differently than regular Dformers?

  • NorthOf45NorthOf45 Posts: 5,482

    You can use the same deformer to squash on one axis and stretch on another. Practice on a torus primitive so that you can clearly see what is happening.

    Scale the deformer to about half the size of the tire. Put the minimum effect on the inside edge of the tire (outside edge of deformer), so that it will affect the part that hits the road (outside edge). Scale that dimension down to flatten the outside of the tire, and increase the cross-wise dimension to make it bulge sideways in the same place. You might need to fiddle with the size and proportions of the field to get more influence in one direction over another.

  • john_antkowiakjohn_antkowiak Posts: 334

    Thank you, NorthOf45. Question about that. My experiments with adjusting the Scale parameters of the Dformer proper have always given unpredictable and counter-intuitive results, so I have generally only manipulated the Translation and Rotation values. Just to be clear - you're saying that I should be working with the Dformer Scale parameters, yes? I do change the Scale parameters of the Dformer field and even the base all the time so I get that part...

  • NorthOf45NorthOf45 Posts: 5,482

    Yeah, manipulating the various parts can get confusing. Adjust the size and position of the field to include the area of interest. It should barely touch the inside edge of the tire, and have greater effect on the outside edge. That means the center of the deformer would be near the outer edge of the tire, or just inside it. Too far away and it might not have enough effect. To flatten the surface, you can scale the D-Former (or translate, since the effect won't touch the inside edge, but the effect is subtly different) towards the center of the tire. If the field is too small, it might make an indentation in the tire (like rolling over a rock) instead of flattening the surface. That's where the size of the field makes a difference. Stretch it out horizontally in both directions to get the effect of flattening the surface just right. 

    To bulge out sideways, scale the D-Former along that axis to stretch the mesh accordingly. You might need to adjust the size of the field to get a good mix of the two effects simultaneously. This is where the vertical position of the field is important, you want the bulge somwhere in the middle of the sidewall, maybe nearer the outside edge. I'll make some screenshots later, I've got a long render cooking...

  • Sven DullahSven Dullah Posts: 7,621
    edited February 2021

    ...meanwhile, some screenshots that show the position and scale of the dformer components...bear in mind that the position of the dformer base is important, it represents the center of scale and rotation. Also zoom in on the wheel and edit the dformer spline curve to see the results in realtime. When one wheel is done, select and copy all three dformer components, create a new dformer, paste, use the parameters/symmetry function (swap left/right, mirror y/z rotations) to copy the left wheel settings to the right wheel. If the car is not 100% symmetric this will need adjusting. My car is a truck so the rear wheels would need different settings, in your case you could copy the front left to a new dformer, parent the field to the base and move it to fit the left rear. Then again, when the settings are made use the symmetry to make the right rear. Hope this helps!

    dformer and the spline curve I used:

    dformer base position

    closeup

    dformer field parameters

    Post edited by Sven Dullah on
  • NorthOf45NorthOf45 Posts: 5,482
    edited February 2021

    Following up with pretty much the same thing. Two tori (toruses?), one untouched, one with the deformer doing it's thing, lined up to show how they compare.

    Thanks, Sven, I always forget that you can alter the curve used by the deformer.

    Flattened torus_1.jpg
    912 x 912 - 91K
    Flattened torus_2.jpg
    913 x 911 - 71K
    Post edited by NorthOf45 on
  • HylasHylas Posts: 4,985

    Have you tried smoothing modifier? Doesn't always work out, but if it does it's a one click solution.

  • Sven DullahSven Dullah Posts: 7,621
    edited February 2021

    NorthOf45 said:

    Thanks, Sven, I always forget that you can alter the curve used by the deformer.

    Yea it's a very useful feature. However I just discovered that ,when copying and pasting to a new deformer, the spline curve reverts to the default ease in- ease out curve. So if using a custom curve it requires manual adjusting for each dformer. Also discovered that the symmetry function does nothing, so looks like that also needs manual adjusting. But for this test I used my ancient laptop with DS 4.7, so maybe it was updated in later DS builds? IIRC I've used symmetry and had it work in DS 4.9 which is what I normally use.

    Edit: Tested symmetry in 4.9 and works as expected, so should work in the most rescent DS build.

    Post edited by Sven Dullah on
  • 31415926543141592654 Posts: 975

    Another option would be to make a morph in Hexagon ... That can work great and be quite detailed ... If you have already become familiar with Hexagon though.

  • onixonix Posts: 282

    In this situation, I would use Zbrush or push modifier with weight map which is similar thing as ZBrush 

    also one of the possibilities is to use a smoothing/collision modifier to bulge tires to the sides create a ball primitive stretch it  put it inside of the tire and set collision for the tire to that sphere

    .

  • Sven DullahSven Dullah Posts: 7,621

    3141592654 said:

    Another option would be to make a morph in Hexagon ... That can work great and be quite detailed ... If you have already become familiar with Hexagon though.

    Yup, good call, and it's free. Personally I haven't tried to use it in years, was quite unstable on the Mac so gave up trying to learn it, should have a new go at it nowyes

  • Sven DullahSven Dullah Posts: 7,621
    edited February 2021

    onix said:

    In this situation, I would use Zbrush or push modifier with weight map which is similar thing as ZBrush 

    Zbrush is probably good...if you have it. Push modifier weight...well to me that sounds like a hell of a lot more work than using a regular dformer.

    also one of the possibilities is to use a smoothing/collision modifier to bulge tires to the sides create a ball primitive stretch it  put it inside of the tire and set collision for the tire to that sphere

    Yes in theory, but not a practical solution. Have you actually tried that? And do note that the dformer field is a sphere that you can scale, only it gives you so much more control than trying to use a smoothing modifier.

    Post edited by Sven Dullah on
  • onixonix Posts: 282

    Sven Dullah said:

    onix said:

    In this situation, I would use Zbrush or push modifier with weight map which is similar thing as ZBrush 

    Zbrush is probably good...if you have it. Push modifier weight...well to me that sounds like a hell of a lot more work than using a regular dformer.

    Not really that much more work. Dformers are also pretty hard to use and it is unclear if you will be able to get the desired result

    also one of the possibilities is to use a smoothing/collision modifier to bulge tires to the sides create a ball primitive stretch it  put it inside of the tire and set collision for the tire to that sphere

    Yes in theory, but not a practical solution. Have you actually tried that? And do note that the dformer field is a sphere that you can scale, only it gives you so much more control than trying to use a smoothing modifier.

    Yes I was actually using that as a method quite often  especially because Dformers do not work on poseable figures if they are not in their zero pose and it is much quicker and simpler than tinkering with dformers

    So it is a practical solution although it may be not fully useful for this purpose because you can only collide something with one item.

    At this time I do not do any of that anymore because it is easier to use Zbrush and make morphs when necessary

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