SBAS - Segment Based Alignment System

Let’s be honest - trying to describe what part of the body is pointing where in dance can get confusing fast. Especially when your feet are pointing one way, your frame another, and your travel vector a third. 😵‍💫

This problem has been addressed by the syllabus manuals 'Alignments' which didn't address the issue of the direction of your body segments (torso, head, feet etc). Over the decades it's become more and more obvious that a system was needed to help dancers understand where their Frame, Head, Hips etc should be facing.

Such issues are very apparent in CBM, CBMP, Promenade Position, Corte, Outside Partner and more.

Take this scenario:

You’re in Closed Position, facing Line of Dance (FLOD) - that means your feet are pointing down the room.

Easy, right?

But now imagine you’re in Promenade Position (PP). Things change:

Lets say your feet point Diagonal Wall (DW),
Your frame (torso) will be turned to facing Wall,
And your travel might be heading straight down LOD again (and yes, it feels like sideways)!

So how do we describe all of that without turning into spaghetti?

🍞 Enter: SBAS

Don’t let the acronym scare you - SBAS is just shorthand for:

SBAS: Segment Based Alignment System

It’s a simple way to describe what direction your hips, torso, or head are facing relative to another body segment or the direction of travel.

SBAS is composed of the following vectors:

T_vec (or Tvec) is the alignment that the hips are about to travel or are already traveling in.
B_vec (or Bvec) is the Body's (or Torso, specifically the sternum) angular offset from your standing foot
F_vec (or Fvec) is the alignment specified in the various syllabi and also an angle with reference to the current Line Of Dance
H_vec (or Hvec) is the angular offset of your head with respect to your torso B_vec

Angles are measured in degrees to the left or right. Negative angles are to the left and positive angles are to the right of T_vec

Here's an example using head positions relative to the body:

Head looking	Description
Left	As in Closed Position Hvec would be about -45o degrees with respect to the body.
Nose over Sternum	As in 'looking ahead' Hvec would be 0o degrees.
Right	Hvec would be about +45o degrees with respect to the body.

Note: SBAS is local to the individual dancer which means that Leader and Follower are very likely to have different values.

And this makes is better.... how?

It's a really good question so lets take a Waltz Box Step as Leader:

We commence Facing LOD (F LOD) and these are the steps (Sway, Footwork and Rise and Fall have been omitted). Yes there is an extended SBAS for Rise and Fall and Sway, we just omitted them for clarity.

Step	Foot Position	Dance Position	Alignment	Turn	CBM	Count
1	LF forward	Closed Position	F LOD	Nil	Nil	1
1	LF forward	Closed Position	F LOD	Nil	Nil	1
3	LF closes to RF	Closed Position	B ALOD	Nil	Nil	3

Step 1:

T_vec is LOD because that's the direction we are moving
F_vec is LOD because that's where the standing foot is pointing
B_vec is 0^o (zero degrees) as there is no body turn, it's a straight line.
H_vec is -45^o because the head is rotated 45 degrees to the left with respect to the sternum.

Steps 2 and 3:

Since this is a basic forward, side, together SBAS is the same as for Step 1.

Left Turning Box Step

Things get more interesting, here's the chart with the SBAS values. To save space (and sanity) since this is all CP:

H_vec is -45^o throughout

Step	Foot Position	Dance Position	Align	Turn	CBM	SBAS	Count
1	LF forward	CP	F LOD	Com to turn L on 1	1	T_vec = -22^o F_vec = -22^o B_vec = -22^o	1
2	RF side	CP	B DW ALOD	1/8 turn L btw 1 and 2	Nil	T_vec = -22^o F_vec = -22^o B_vec = -22^o	2
3	LF closes to RF	CP	B W	1/8 turn L btw 2 and 3	Nil	T_vec = -22^o F_vec = -22^o B_vec = -22^o	3

Step 1

T_vec is -22^o since it's a 'commence to turn L' will have rotated the body creating CBM
F_vec is -22^o due to the body rotation and CBM
B_vec is -22^o because the body has rotated.

Step 2

Everything is the same as step 1 as it's an 1/8th turn which has effectively already been done. (See CBM)

T_vec is -22^o since it's a 'commence to turn L' will have rotated the body creating CBM
F_vec is -22^o due to the body rotation and CBM
B_vec is -22^o because the body has rotated.

Step 3

T_vec is B W (or F C or LOD depending on what the next step is.)
F_vec is B W as the next step (step 4) will be backing (and things get more interesting)
B_vec is -0^o because the sternum is an angle relative to the standing foot which in this case is zero. It's easy to check, just look down and your foot will be there :-)

Now steps 4 though 6

Step	Foot Position	Dance Position	Alignment	Turn	CBM	SBAS	Count
4	RF back	CP	B W	Com to turn L on 4	4	T_vec is B W	1
5	LF side	CP	P ALOD	1/4 turn L btw 4 and 5, BTL	Nil	F_vec is B W	2
6	RF closes to LF	CP	F ALOD	BCT on 6	Nil	B_vec is -0^o

Step 4

T_vec is -22^o since it's a 'commence to turn L' will have rotated the body creating CBM
F_vec is -22^o due to the body rotation and CBM
B_vec is -22^o because the body has rotated.

Step 5

T_vec is B W (backing wall)
F_vec is -22^o due to the body rotation and CBM. Note that moving foot is F_vec is -135^o
B_vec is approximately -67^o which is half of the 3/8 rotation. Remember this is with respect to the standing right foot which has also rotated -22^o. B_vec is approximately facing F DC ALOD

Step 6

T_vec is F ALOD
F_vec F ALOD
B_vec is -0^o because the sternum is an angle relative to the standing foot which in this case is zero. It's easy to check, just look down and your foot will be there :-)

Promenade Position (Leader)

Let’s say the Leader’s feet are pointing DW (which means the alignment is DW)

Vector	Angle	Relative to
T_vec	LOD	alignment in room
B_vec	+45°	With respect to the standing foot (F_vec). In this case the alignment would be W
_vec	-45°	Sternum
F_vec	+45°	F DW

and the first step **T_vec would be travelling LOD.

👠 Example: Promenade Position (Follower)

(Correct alignment and angles shown, there is no V-shape to avoid breaking Frame.

Follower’s feet are pointing DC.

Vector	Angle	Relative to
T_vec/td>	LOD	alignment in room
B_vec	+45°	With respect to the standing foot F_vec. In this case the alignment would be W
H_vec	-45°	Sternum
F_vec/td>	+45°	F DW

Note that as you step in Promenade

Try it!!

Suddenly you have an angle relative to something else that you can use to precisely position yourself. No more wondering WTH because the Manual didn't give the information you actually need to accomplish the figure.

Remember that negative angles are to the left and positive numbers are to the right'

SBAS makes it super easy to define what's going on - no need to know where you're traveling or even what step you’re on. Just look at another body segment and measure the angle from there.

This is especially important given the more realistic 'Realistic Alignment Chart'

In the interests of Pedantry and resolving a Conundrum !

We have chosen to have angles relative to the standing foot (F_vec) rather than T_vec because it's easier to see your standing foot. Look down and there it is.

Alternatively we could have used T_vec as the reference point which actually makes sense mathematically but is harder to visualize especially for Lunges, Corte's, Promenades, pivots and some turns.

One of the deciding factors relates to the established alignment tables being taken too literally. The more realistic map is the one actually being danced where the alignments are actually 22.5^o either side of the 'ideal' angle. The only consistent reference point is the standing foot as ultimately everything else is based on it's position.