Perfect circle in a polygon grid?

[mocaw]

Well one way is with boolean operations- and then a bit of clean up as needed.

If it's a sub patched object then you'll be able to do it just with a square shaped set of polygons depending on how the mesh is.

You can also take some extra points, grab a nurbs circle from the Model->Get->primitive->curves area, take that- place it where you wan the circle, grab your points on your mesh that you want to form the circle, and then shrink wrap those to the circle using one of the closest settings (such as Closest Vertex)...

If you need the circle to try and adhere to the surface topology of the mesh you could either manually snap the points to the surface or use shrink wrap first on it- THEN grab your points and shrink wrap them to the curve. This method works well for sub-division surfaces...

There are probably five other ways to do this before even getting in to ways you could use ICE to do it as well...

Can you show a wire of the area/fender?

[wannabeArtist]

Thanks for the tips!

Gotta try those out first thing tomorrow -almost midnight here :)

Here's the current (polygon) mesh - it's now subdivided compared to the previous thread and I have separated the doors etc.

Anyways, I quickly added a circle to approximately the spot, where the fuel tank cap is supposed to be. Actually it will be on the other side, but I don't even have an accurate reference of that placement yet :) The problem is of course the same.

http://i42.tinypic.com/ziukvs.jpg

[Jettatore]

Well you gave yourself reference, so in the side view just draw it in manually, should be simple.

[wannabeArtist]

Hello,

It's not really the about the reference, it's about the correct topology that needs to be used to make a circular hole in a boxy polygon mesh.

I stumbled upon some instructions (http://www.digitaltutors.com/forum/showthread.php?t=2624)in another forum. They are for Maya, but I tried to follow them anyway and came up with this little test cube (smooth and original version):

Not entirely satisfactory, though - I'm not willing to use this for the car, at least not until I tried the other ways.

Gideon, any idea how ICE could be used to do this? That would be cool to learn, learning to use ICE generally has been on my todo-list for a while anyway :)


http://i39.tinypic.com/whmp3k.jpg

[eldee]

here's how I do it, hope it helps:

http://img26.imageshack.us/img26/2474/holesa.jpg

[wannabeArtist]

Dinner? But I just had breakfast...

Just joking :) Thanks, that's about as detailed as instructions can be - I could not mess it up following that!

[mocaw]

eldee's method is an ever better one than mine- same concept, but much better exicution and control IMHO.

The maya example uses too many polygons AND has a bunch of tri's in it...which is fine if you want to subdivide more than you should...but with "pole" like things it could cause issues with smoothing etc esp. in different packages (you can see OpenGL shading issues on the example). Best to try a "more pure" method like eldee's first!

Thanks for the tip eldee BTW.

[eldee]

it's also worth noting that if you've got some kind of uneven surface you're trying to punch a hole in, you can use this method just as easily by using reference mode and picking each individual edge, and then only snapping the points in X/Z so you keep the overall shape.

[wannabeArtist]

Thanks for pointing that out also,

I went and tried out this method by spending this morning modeling out my mp3 player :) (Bump maps took me most of that time, fortunately someone helped me out on this forum).

It's got a round display and a control "wheel". The cylinder-method works like a charm, really a great addition to my 3d-"toolbox" :)

http://i39.tinypic.com/wjcem9.jpg

[grahamef]

Deform > Relax is also useful for turning a square outline into a circle. Just turn off Consider Unselected Vertices and Boundary Vertices as appropriate.

[wannabeArtist]

Circle skill required again :D

Any tips how to do this - preferably with eldee's method - if the the surface is curved (not flat)?

Is there a way to accurately copy that curvature to the cylinder so you can use point snap or what? It's a polygon mesh.

I've been trying to get lug nuts on my car rims for a while here, and I'm not really getting a clean result. It seems tricky to keep the rim curvature intact, while punching a circular hole or recess through it. Check out the picture to what I mean:

http://i40.tinypic.com/qnn0ur.jpg

or this picture (http://imgs.tootoo.com/ba/b3/bab3f74135de58c95b05398969cfe7f9.jpg)I just googled.



Thanks, grahamef, that relax will work on some situations, good to remember that also.

[wannabeArtist]

update:

Kind of solved that myself by adding an edge loop on the cylinder and tweaking the points so they meet the surface. If anyone has a better idea, go ahead and post it :)

[eldee]

yeah, if i have a curved surface I basically just move the points in the adjacent axis.. this doesn't really work if the curve is off-axis, in which case scenario you can always use a transient reference plane and move according to that. but yeah, just snap to face and move toward the surface.

[wannabeArtist]

Thanks,

The recess turned out pretty nice (pic (http://i39.tinypic.com/de0nlu.jpg)).

Now I would need to figure out how to copy that over 4 times to get the rest of them in place. Any tips on that? Can I select and copy exactly 20% of the wheel rim? Or am I better of just repeating the cylinder process on the 4 remaining recess as well?

[eldee]

i'd just extract out the affected polys, move the temp center (alt button) to the center of the wheel, and then shift-rotate to snap it to even angles. then just duplicate and repeat

[wannabeArtist]

Thanks,

In fact I figured out pretty much the same solution myself and started working on it just when your reply came :) Well, that was quite fast and I'm happy with this rim for now!

http://i41.tinypic.com/ru1get.jpg

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