3DS Max render issue

[Irishrailguy]

So here I am with another 3DS Max issue. I can't understand why these shading issues are coming up, the particular mesh I'm dealing with is a complex throttle shape, the handle itself is easily made with a cylinder, using some extruding and scaling I can get the shape easily. However, when I go to render it with the Mental Ray renderer, the shadows aren't consistent with the mesh shape, you can see in the image below, that the shading on the modified cylinder isn't smooth and graduated like the standard one on the right.
[url=http://www.mynetimages.com/1ee0ca4a2b.jpg[/url]
I haven't moved individual vertices, I've only used scale and extrude. I've also done all the smoothing groups myself, making sure that there wouldn't be any artifacts. There is also some notable shading at the end of the modified cylinder showing up the triangulation, which I know shouldn't be happening in any situation.

So can anyone tell me why the shading on the cylinder on the left isn't smooth, but more like blotchy, I've never experienced shading like this on any mesh I've made, even with ones where I'm moving around individual vertices myself.

Kev

[Tankski]

A wireframe of the object would probably be more useful at the moment, that's showing smoothing errors, however, so make sure there's nothing up with the smoothing groups.

[Irishrailguy]

A wireframe of the object would probably be more useful at the moment, that's showing smoothing errors, however, so make sure there's nothing up with the smoothing groups.

Thanks for the help, I'll put up a wireframe tomorrow first thing. About the smoothing groups, that's the one thing that I'm wondering about, the grooves are 2 SG's (one per side of the groove) and the rest of it is one SG, so I don't have a clue why there's errors. The triangulation is also noticeable in the smoothing, which never happens on any mesh I make, so there's something odd going on here

Thanks,

Kev

[Irishrailguy]

Ok, here's the wireframe, I've made sure that all vertices are correctly welded etc. so at this point I don't see any mesh errors.

Thanks,

Kev

[Tankski]

I'll see if I can replicate the error, your topology looks clean and from what you say the smoothing groups are fine. I'll keep you posted with my results.

[Tankski]

That's what I got through re-creating what you have made, I used 20 cylinder faces to create the cylinder, and I have no smoothing errors to report.

You've gone horribly wrong somewhere in the making of that handle, I'd suggest re-modelling that particular piece of the cab.

[Irishrailguy]

Well that looks identical to the one I have, my Max is full of bizarre errors and one which may play a part in this is the scale gizmo in local mode. In fact any transform gizmo in local mode sometimes gets squashed or stretched an weird things happen when I use it. I'll report back when I make progress.

Thanks,

Kev