Spline Problems

[earthquake]

Hi All

 

I'm working on a model and I can't get the splines to act right. The spline fallows the curve right between the CPs but in some places between 2 CPs the curve flips, like in this image:

 

 

and you end up with divots where I don't want them, as in this image:

 

 

I only have 2 = 3 point patches and 2 straight splines. All other patches are 4 point. Here is an image of the splines:

 

 

I've tried to refind normals, I selected one of these weird splines and tried to flip the normal and I tried using the smooth tool, all with no effect. This model looks OK with the toon shader turned on:

 

 

but I'm trying to use him as a standard 3d caricature, not a toon. Can someone tell me where I'm going wrong and what I can do about it? Any help will be greatly appreciated.

 

I'm using 15g, if that matters.

 

 

Thanks

earthquake

[HomeSlice]

One thing is that there are 2x or 3x more vertical splines in the legs and body than you need. And there are far too many splines in the front of the body, throat and lower lips. The more splines you have, the more careful you have to be about tweaking the CPs to form graceful curves. If you think about it a little, it makes sense why this is so.

You may also want to check the biases (alpha and gamma) for the CPs in the problem area. You may be able to tweak either the alpha or gamma to smooth out some of the areas, but first, you should get rid of a bunch of those vertical splines. One thing you can do to accomplish that is to use hooks up near the hair to end some of those at the forehead and side of the head, instead of running those splines all the way down the body.

[earthquake]

Hi HomeSlice

 

After reading more threads on splines, I can see you are right. I'm going to reduce the vertical splines to start with, should I reduce them by half or two thirds, what would you recommend? How do I determine if the biases are alpha or gamma and how can I change them if needed?

 

Thanks in advance for any info..

[HomeSlice]

First, make a copy of your original model, so you can go back to it if you need to.

Then try reducing by 1/2 (more or less) and see if that helps.

Make a copy of that model too.

Then reduce further.

See how far you can reduce the splines while still keeping the necessary form.

Once you can model effectively with the minimum number of splines possible, it is easier to add density while keeping a smooth mesh. I don't know why that is ... it just worked out that way for me.

 

The settings for adjusting the Control Point Bias for each CP are found in the Model's Properties panel, under "Bias". You can drag the mouse horizontally over "Alpha" or "Gamma" to increase or decrease the values. Alternatively, you can click on the "Show Bias Handles" button up in the main toolbar to show a pair of handles for whichever CP is selected. Then you can drag the handles around to change Magnitude/Alpha/Gamma.

[robcat2075]

A typical round cross section like a neck or a torso or a leg might have 8 CPs and you've got... 30? Yeah that's a lot.

 

the head needs quite a few splines for the spikes at the top but those can be terminated in hooks before they stretch all the way down the face.

 

Not a bad model , even with the excessive splines!

[earthquake]

Thanks for all the quick feedback. I'll start reducing the splines by half on the head to start, the head is the hardest part. Can you sagest a good tut on hooks. something more dedicated to hooks than the giraffe tut.

 

til later

Thanks

earthquake

[robcat2075]

Thanks for all the quick feedback. I'll start reducing the splines by half on the head to start, the head is the hardest part. Can you sagest a good tut on hooks. something more dedicated to hooks than the giraffe tut.

 

Hooks are simple things and the giraffe tut probably covers most o f it.

 

A hook can be connected to the 1/4, 1/2, or 3/4 point of the spline it hooks to, so potentially you could have 3 hooks attaching between 2 CPs. I avoid that and stick with just one in the mid point.

[Malo]

hello,

 

nice model

Just a note, on the nose, it is possible to eliminate these two splines.

 

 

The use of patches with 5 points, in some cases allow a smoother modeling.

 

it seems that the tip of your nose is close as the first example of this. I advise the second way.

 

[earthquake]

Hi All

 

Sometimes I have to get kicked in the head a couple times before I get it, but I think I understand hooks OK now. I reduced the vertical splines in my models head by at least 50% and it now looks pretty good, or at least better. Here is a pict of the new model:

 

 

And here is pict of the repaired splines:

 

 

I haven't repaired the body yet, but I'll post a pict here when I'm done. HomeSlice, thanks for the info on the bias controls, I can see it will save me alot of time in the future.

 

I used a program that uses polys in the past and to make barts head would take 2000 plus polys to look decent. This is one of my first caricatures, I mainly have built mechanical objects In that other program.

 

I would like to thank you all for the info and quick response.

 

 

until later

Thanks

earthquake

[robcat2075]

You can also use hooks to reduce some splines coming out of the eye sockets before they have to loop around the back of the head.

[Malo]

A little trick to eliminate quickly splines (which can be useful if you do not know).

 

 

Note (windows key)

 

A: select a CP of the spline.

B: press "," key (to select the spline)

C: two way:

Ca, if you want to delete the spline, and keep the CPs. Press delete key

Cb, if you want to delete the spline and the CPs. press twice "." key, and press delete key

[robcat2075]

Cb, if you want to delete the spline and the CPs. press twice ";" key, and press delete key

 

For confused Americans, on US Keyboards it's the "." key.

 

Our keyboard layout is rather different than European ones it seems.

[NancyGormezano]

if you want to delete the spline and the CPs. press twice ";" key, and press delete key

 

Malo - you are terrific at distilling information in a logical manner -

 

But I think it's the "." key for option Cb ?

 

EDIT: of course robcat beat me to it, and explained why

[Malo]

Oops, sorry , of course not the key ";" but the "."

Thank you for having corrected

 

Original post edited.

[earthquake]

Hi All

 

Thanks Malo, cool trick.

 

Here is the latest version of the model, looking better:

 

 

and here is a shaded wire-frame of the new splines, I've reduced the splines of the body by at least 75%:

 

 

I'm still having bias problems:

 

 

Before I tweak every spline, one at a time, does anyone know any tricks to either tweak, or default the entire splines bias at once? Does less patches equal less rendering time?

 

On a caricature model do you need to have all splines interconnected, or can you have, say a sheave and stick a hand in it with just the splines crossing? Or will the model break up when you animate it that way?

 

This is a model I built in that other program, around 13k polys:

 

 

I think the next model I build in A:M will be another hotrod. I can see it with 1500 patches or less, with the same detail.

 

Thanks, Your help is greatly appreciated.

 

 

until later

earthquake

[robcat2075]

Hold on there. Those hooks you have coming out of the top of the head are not hooks. If you've done it right there won't be a red CP there.

 

If you're trying to attach a hook where there's already a CP you wont' get a hook. Delete the CP where you think you're making a hook. There should not be a CP there, before or after.

[Malo]

I have in mind two cases for this kind of render.

 

 

The first case, the bias* or rather a broken spline ("O" (for smooth) an "P" (for peak) key). ( A)

* You will find a plugin (written by Emilio Leroux, thank to him) for apply the same bias to your model, at this link:

http://www.moscafilms.com.br/emilioleroux/...ns_setbias.html

 

The second case (, when three splines (or more) cross.

advise : do not cross over two splines

 

 

Your ear can be simplified.

The spline under the nose does not seem necessary.

[earthquake]

Hold on there. Those hooks you have coming out of the top of the head are not hooks. If you've done it right there won't be a red CP there.

 

If you're trying to attach a hook where there's already a CP you wont' get a hook. Delete the CP where you think you're making a hook. There should not be a CP there, before or after.

 

 

Hi Rob

 

I think I finally have the hooks figured out, check this image and let me know:

 

 

Thanks for all your help.

[earthquake]

I have in mind two cases for this kind of render.

 

 

The first case, the bias* or rather a broken spline ("O" (for smooth) an "P" (for peak) key). ( A)

* You will find a plugin (written by Emilio Leroux, thank to him) for apply the same bias to your model, at this link:

http://www.moscafilms.com.br/emilioleroux/...ns_setbias.html

 

The second case (, when three splines (or more) cross.

advise : do not cross over two splines

 

 

Your ear can be simplified.

The spline under the nose does not seem necessary.

 

Hi Malo

 

You're right, the vertical spline is through and through, but the horizontal spline ends at the CP, check image:

 

 

How do I fix this, how can I join the horizontal spline at that CP? Do I need to join the horizontal splines together before I attach it to the vertical splines CP?

 

Thanks for all of your help.

 

until later

earthquake

 

[robcat2075]

I think I finally have the hooks figured out, check this image and let me know:

 

Ah... much better.

[Malo]

Hi earthquake,

 

if it is the first case select the cp and press "o" key

if it is the second case, select the CP, "Shift K", and attach it again (right klik, on Windows).

 

[earthquake]

Hi Malo

 

It was case B, connecting those splines smoothed the model right out,

 

 

eliminating the creases, right-on.

 

Now for the arms.

 

Thanks again for the help.

 

 

til later

earthquake