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daz1761
08-24-2011, 12:02 PM
I'm trying to create a spinning wheel and when I sent the object to Layout I adjusted the pivot point as close to the center as poss and started animating and the wheel wobbles just like it has in the past with other projects.

Is there a way I can get modeler or layout to position the pivot exactly in the center of my objects to avoid this problem in the future?

Many thanks

evenflcw
08-24-2011, 12:28 PM
There is a center pivot (or somesuch) command in Modeler... so just select a point at the center of the hub and run the command. If you the wheels at a non axis alignment then just follow up with the rotation manually afterwards.

If you got all wheels in a single layer, then just use Point Info (in Modeler) to get the coordinates of points in the center of each hub, and paste that onto nulls, bones or whatever.

If you have no point at the center of the hubs, create some.

PS. Are you sure the wheel is perfectly round?

nickdigital
08-24-2011, 12:28 PM
Yes, there should be a Center Pivot button in Modeler. It should center the pivot based on your selection.

daz1761
08-24-2011, 12:42 PM
Cheers guys

After I posted this thread I did find the "Center Pivot" in modeler which seemed to do what it said on the tin but as soon as I animated it again in a fresh version of layout it was wobbling yet again :(

Its defo circular 100% as I made it with a primitive "Disc" BUT the only problem is, that I have used a circular tube to Boolean out the center which I admit that probably wasn't subtracted dead on center tho



Thanks

evenflcw
08-24-2011, 12:55 PM
The reason for selecting only a single point is to avoid any bias presented by non-symmetrical point placement. Point averages is not the same as geometric/volumetric average. If your boolean(s) weren't symmetrical the resulting point averages won't be either. To create the center point if you got none, just grab a pair or more points with rotational symmetry, weld, copy, undo and paste. That should give you the point you need. Leave it there for future reference. It won't render anyway.

daz1761
08-24-2011, 01:12 PM
The reason for selecting only a single point is to avoid any bias presented by non-symmetrical point placement. Point averages is not the same as geometric/volumetric average. If your boolean(s) weren't symmetrical the resulting point averages won't be either. To create the center point if you got none, just grab a pair or more points with rotational symmetry, weld, copy, undo and paste. That should give you the point you need. Leave it there for future reference. It won't render anyway.

Thanks for that...

I did try the above and couldn't quite understand your instructions regarding which points to weld

I have pressed F2 to make sure the circular object is centered

I have attached a screen grab of modeler hoping you can point me in the right direction

Thanks again

evenflcw
08-24-2011, 02:11 PM
Just select all points on the outer ring of that tire, use weld average on them to join them at a common center, copy that point, undo to revert the weld operation and paste the center point back. Then use center pivot with only that point selected.

PS. sorry, I see now I forgot to specify weld average in the last post.

daz1761
08-24-2011, 02:46 PM
Just select all points on the outer ring of that tire, use weld average on them to join them at a common center, copy that point, undo to revert the weld operation and paste the center point back. Then use center pivot with only that point selected.

PS. sorry, I see now I forgot to specify weld average in the last post.

Thank you

No worries, i have followed your instructions which now make a lot of sense but the average point it has chosen is way off the center which baffles me as I did draw the disc using the middle mouse button to constrain the circle, do you think maybe it was the multishift tool that has upset my wheel? as I used it to bevel inwards the edge of the wheel with "Shift: Point Normals" set in the numerics pane

I have uploaded another pic to show you where exactly the average weld decided to place the point

Many thanks

evenflcw
08-24-2011, 02:55 PM
Well... I don't know. You really only need a center point if you don't want to align the wheel to the major axis.

If you did do an F2 (Center 3d??? I dont have default keyboard setup and dont think putting arbitrary functions onto function keys is a good idea... because its arbitrary) then the pivot should be at the origin, as I suppose the Center fuction uses the bounding box center, which should almost coincide with the geometric center for this wheel. I say almost because your wheel has an uneven number of points and thus one side will extend slightly further than the opposing edge on the other side. Ie, unless you have a good reason not to, then it's often best to create circles with sides divisible by 4.

4dartist
08-24-2011, 02:58 PM
I don't think I'm in the majority but I NEVER adjust pivot points in modeler. It creates one level of complexity you don't really need and causes confusion when parenting because you don't know if you are using the pivots coordinates or the object's origin. That may be because I never mastered working like that!

What I do and have done for years and it serves me well is use null objects. Just go into layout, go to a side view, toggle to wireframe mode, create a null object, place it in the correct spot on the wheel, zoom in as much as you need. (sometimes it helps to turn the circular object's subd level to 0 just to make it clear) Lastly, now that the null is lined up on the wheels rotation axis just slide it over so it's where you want it in the other axis and parent the wheel to it. Done.

If you don't have any geometry in the exact middle you can create a guide really quick then delete it once you have found it. Just extrude a row of points and scale it down to 0 using 'selection mode' under Modes in modeler. That'll be your center point.

SteveH
08-24-2011, 03:22 PM
If non of this works for you Daz - then if I was to guess your wheel and your center hub don't have the came center. You stated below you weren't sure if the disc you booleaned out was at the exact center of your wheel.

Try getting the center point of the wheel using the outside polygons and weld average - and do the same thing with the center hub/openign of yoru wheel and see if they are the same points. If not then your wheel will alwasy seem to wobble if you are using the center hub's center point. I think you'd want th eoutside wheel polygon's center point as th eroattion point. I hope that made sense.....:)

daz1761
08-24-2011, 04:02 PM
97744Cheers guys

All the suggestions make sense especially working in 4's when using circular objects which I will defo stick to in future.....

Sadly my wheel is broken now due to crazy geometry, i'm trying to do an edge bevel on the outer area where the wheel is beveled in to smooth it out and the bottom half is beveling fine and the top half is just breaking up, its not even "selecting loop" all the way around the wheel, its only selecting half of the wheels edges which ive never seen before :(

Ive selected polys and hidden them to see whats happening behind the scenes and there seems to be 2 lines joining the front face of the wheel that are unselectable.

Im quite new to modeling and i half only built a few things but most of them are turning out like this with crazy broken geometry :(

Also, when you undo after the edge bevel, the part of the object that breaks becomes deselcted whilst all other edges are selected

Here is a picture to explain more......