When I first learn 3D animation via Blender there where many new concepts for me to try and understand. One of which was, how do you define the location of a 3D object in relationship to it's world, the 2D computer screen. The answer is something that you learn in 7th grade Algebra, the X, Y & Z coordinate.

Blender uses the Right Handed Cartesian Convention .

X = horizontal location (left/right)

Y = depth location (front/back)

The location 0,0,0 (X,Y,Z) is is the center.

For those who want a more scientific explanation as to why this is, you can check Wikipedia.org for the right and left handed Cartesian coordinate Convention.

**Splinaphobia**by

**Pixar's Victor Navone**that discusses animating using Splines. It's rare that we get a glimpse into how the Pros work so this is definitely worth checking out.

In Blender terms, splines = the IPO Curve via the IPO Curve editor.

Just remember while going through his exercises that Y is the vertical axis in Victor's tutorial and in Blender it's Z.

## 17 Comments

Interesting read good work

Hi, Tim.

That's a really good resource. Victor Navone is really ultra-superb animator with a great site (everyone should check out his site and demo reels for inspiration)

But I think you should change the name from "splinophobia" to "splinophilia", which is the actual name of his tutorials. "phobia" is the opposite of the idea of his tuts.. ;)

Thanks for sharing!

Cheers

The real pros use splines for everything and never touch polygons even for modeling. Even a straight line is a spline;). That's why we need to fix NURBS in blender.

Esben- Not necessarily. Both NURBS and polygons are used in the professional industry. Polygons in particular are used for organic characters and NURBS for mechanical objects, though you could easily switch that as well. I personally prefer polygons anyway.

By the way, this has nothing to do with NURBS. ;-)

Blender's animation splines are THE NICEST i have ever used. The versatility that you can get per-handle instead of per-point is wonderful, and it's one of the reasons that I can never go back to 3d max.

Right Alden, this is about IPOs, not modelling. Also, lots "real pros" do use polygons for their modelling. I doubt there would be such a push to develop better subsurface modelling in the big commercial apps if people weren't using polys. Also, in addition to NURBS only modelling apps like Rhino there are also Poly only apps like Mirai.

VirgilioVasconcelos,

Good catch. Part 1 is Splinaphobia. I didn't notice the difference in the tutorial title and part 1 title.

Thanks.

Hi Tim,

there is a typo in the header. It should be 'Curves' instead of 'Cruves'.

A bit off topic:

As for 3DS Max and Maya: both use right handed coordinates (look at some screenshots). In Blender and Max Z points up and Y points away from the front view. Mayas coordinates are rotated 90 degrees around X so that Y points up and Z points straight in your face (in front view). But all are right handed and I know of no application (3D or CAD) that uses a left handed system (and I used some, I am an engineer).

Hi Tim,

I didn't notice first but your coordinate system (xyz-2.jpg) is LEFT handed. It becomes right handed if you switch the direction of _one_ of the axes.

LayBack,

The XYZ JPG, it a rotated screen shot of Blender, split between front and side view where X & Y are on the horizontal plane, X is positive to the right and Z points up, making it right handed.

Also, I didn't realize that about the other applications. So I've edited the article.

Thanks for spotting that.

Hi Tim,

I have to correct myself. I just read about POVray having a left handed coordinate system ...

Please (re)read http://en.wikipedia.org/wiki/Right-hand_rule Right-handed-ness is not about pointing "up" or some where else. It is about the relation of the three axes to one another. You could even have X pointing "up" and still have a right-handed system. Read the article above and try the rule as shown in the picture there.

LayBack,

Hmmm, I'll leave up the definition to the mathematicians and engineers. The main point I wanted to convey is that up is Z in Blender and in Maya, which Victor is using, Y is up.

Perhaps for future articles with these types of technical details, I could use you as a source to verify that my information is correct.

Again, Thanks for clarifying it.

I am a math major, and I can confirm that the coordinate system in the picture is definitely a left-handed coordinate system. To determine whether or not the coordinate system is right or left-handed, point your right hand in the direction of the x+ axis, and curl your fingers in the y+ direction. If your thumb points in the z+ direction, the coordinate system is right-handed. Otherwise, it is left-handed.

Also as a math major, my knowledge about Blender made a lot of mathematical principles a lot more fun to learn about. The IPO editor corrisponds very nicely to parametric graphing. Additionally, the slope of any of the curves is the speed of the object, which comes straight from differential calculus. I also believe that it is a lot easier for me to visualize 3D objects due to my proficicency in Blender. Blender is a great example of an application for math.

Sovereignncc-e,

Thank you for clarifying that, your explanation made it easier for me to understand and you are so right about learning with Blender. I was able to help my 12 year old daughter to understand her math, volume, unwrapping solids, X & Yplotting etc. It made it much easier for her to visualize the concepts. using Blender.

> Blender's animation splines are THE NICEST i have ever used.

You might change your mind if you spend some time in Maya's or Houdini's graph editor. The sorting and filtering options, per-key interpolation functions, choice of Eulers/quaternions for rotations etc. make one really feel the difference.

One of the biggest problems about using IPO editor for character animation, is that unlike the Spline Editor shown in Navone's tutorial, Blender's uses Quaternions in the interface. This problem was already discussed in the funboard list. More tools to switch among Euler/Quaternions should be added before you can really concentrate in working with IPOs for character animation.

Regards

Your tutorial is good,

I am looking for some help to learn the Ipo Curve editor and its uses regarding the Blender.

I am finding any help hardly about that.

Could you please help me out.