Why do I get creases and dents in my splines?

[fybs]

Sorry Rodney, do not know where to post this!

Why do I get creases and dents in my splines?

Now this problem does not happen all the time, just on some tied places and curves.

When I move (translate) a control point the new spline has a dent. Where does this dent come from? I have checked the difference with Peak and Smooth but that does not solve the problem. I tried to adjust the problem with the bias handles but no success.

I have a jpg image that I would like to show you so you can see what I mean. Also I did not have this problem with the giraffe, maybe because I put more or less every control point to the same place as the tutorial but the problem started to appear in Exercise 11.5 Make a Face. I started another face from scratch and there where my creases again already near the beginning. So before I continue I thought I might ask your friendly advise again.

I thank you and anyone else that can give me some advise how to avoid those creases and strange curves just before the control points.

Thanx

Fybs.

[Dhar]

Could you provide a shaded wire frame and a wireframe scrn. capt.?

[fybs]

Could you provide a shaded wire frame and a wireframe scrn. capt.?

 

I would love to but I don’t know how to take a screen shot on a PC. Or do you know how else I can get you a jpg of a wire frame. I also don’t know what you mean by wire frame scrn. capt. I’m sorry…..

Thank you for trying to help me out!

[rossk]

I think this might be able to help you out some--

clicky

[KenH]

If you press the zero key (on the keyboard) in AM, that'll be what we want. It's the wireframe shaded view.

You could render out such a view by setting it in the render options, but an easier way is to press the "Print Screen" key on the keyboard. You can then open a new image in your favourite 2D software and press Control V to paste the screen grab into the image. Then save as a jpeg.

 

As for your original question, it looks like you're joining too many splines into the one cp. The above tutorial should help with that.

[Slipin Lizard]

Dhar's right, we need to really see a wireframe to know what's actually happening, but at the bottom of your model I don't like the look of those edges...

 

Creases can happen for various reasons, but my guess here is one of two problems, or even more likely, a combination of both. First off, make sure that no more that four splines intersect one CP. So if the CP represents the "intersection", then you don't want any more than four "roads" converging. Another thing that can cause creasing is the alpha and gamma settings of the CP. When you're modeling and moving around CPs, attaching, unattaching, repositioning, etc, you can end up with some pretty strange values for the gamma and the alpha. These are basically the settings of curvature coming into the CP. It's almost like a having a piece of flexible plastic or tin foil. If you try to shape it by using gradual, smooth bends, the shape will stay smooth, but it you try to bend it really agressively, it'll crease. Remember the CP is a fixed point in space that the computer draws the splines to. If the path through the CP is simple and clear, the junction will be smooth. But if you get to drastic of shifts in direction, you'll be more likely to create creases.

 

Don't be afraid to do your model, or part of it, once, then keeping that as a "safe" copy, start from scratch all over again. You'll be surprised how often you do it much better the second time round.

 

For the Gamma and Alpha values, click the "show info" button top right toolbar.

 

With practice, you'll intuitively know how to avoid creasing in Hash, and your modeling will be much easier. It just takes practice.

 

To take a screen capture, open AM up, display the model in wireframe, and then hit your "print screen" button on your keyboard. Now open up any image program like Photoshop or whatever (I think even Word will do) and create a new file. You'll see under the Edit menu you have the option to paste. Do so, and your screen capture should appear. Size and crop as needed.

 

EDIT: Two people responded in the time it took to right this thing... people are on the ball today!

[fybs]

Thank you all. You have been very helpful. I take your advises and I think Slipin Lizard was definitely right that it will need first of all practice in finding out how to avoid those creases. My mistake was my excitement. I was too much in a hurry building this character I have been waiting so long to build. So now, I know that I have to plan my model more schematically for now. It definitely makes sense.

I also like the explanation of gamma and alpha. That is exactly what I experienced. In time I am sure I will understand.

I am downloading KenH’s advise the Avoid creases in your model tutorial and I thank you all for looking after me.

Fybs.

[UGP]

Seems to me like a bad case of ")(" splines...

 

Just keep the splines continuous and evenly or gradiently spaced.

 

Alpha and gamma could may be the problem though just click any cp, tap the "/" button , and set them to 100.

[DarkLimit]

study these tuts and half ur problem will no longer be......

 

http://www.alienlogo.com/tincan/Spline1.htm

 

http://www.alienlogo.com/tincan/Spline2.htm

[Slipin Lizard]

All those tutorials, including the two Dark Limit is suggesting, are not only helpful, but really vital in gaining understanding of how CPs and Splines work together. However, I don't mean this the wrong way, but I don't think UGP is making a good suggestion (or sense?)... The ")(" splines? Not sure what he means, possibly a cryptic reference to CPs with more than four splines coming into them. Regardless, hitting the "/" after selecting one CP simply selects all CPs that are connected in any way to the first, so if your model is a unibody, it will select the whole model. Why you would then want to set your Alpha and Gamma to 100 in an effort to avoid creases is beyond me, it will most certainly create them.

 

Just do those tutorials, and then keep practicing modeling. Keep in mind that spline modeling takes a little getting used to at first, but once you figure out how CPs and Splines work together, and how to make the Alpha and Gamma work for you, you'll find that its pretty easy and fast to create just about any object you want. Here's a couple of tips for you:

 

-save your work after any major success, but especially just before you delve into some unexplored splinemanship territory. This will allow you to experiment, and if things go wonky, you can quickly just revert or reopen the last saved version (I do this ALL the time).

 

-in modeling and working with splines, try to avoid doing a procedure "just because it works" but without understanding why. Its sometimes hard to not just push on, but try to understand the why, and then you'll be able to fix problems when the occur.

 

-if you're working on a patch intensive model, and you are trying to figure something out, see if you can figure out the principal of what you are trying to do on a seperate model. Experiment on something risk free, then apply what you have learned to your project.

 

-you might want to check out Anzovin's "QuickStart 2" CD, its great, and covers a lot of these issuses. Same goes for David Rodgers book "Animation Master 2002: A Complete Guide", the opening chapters on modeling are excellent, but also he is coming out with a new version soon, so you might want to wait for that one.

 

www.anzovin.com is the Anzovin website. Oh yeah, and most people miss this one, but learning to build the primitives from scratch that come AM is also a great way to learn, too.

 

Good Luck!