Understanding the rules for centering a sign

Valerie Sutton sutton at SIGNWRITING.ORG
Sat Oct 9 15:38:56 UTC 2010

SignWriting List
October 9, 2010

Hello Steve and everyone!
Good morning on a lovely Saturday morning here in San Diego, California ;-)

I am sitting here with my early morning cup of coffee trying to think through your questions, which are very interesting, but the answers are not that simple....why?

Because there are two kinds of centering in SignWriting....

1. Centering while writing an individual sign, based on SignSpelling Rules 1 and 2


2. Centering "signs-already-written" in sentences, in three vertical lanes.

Two different centering issues.

I believe, Steve, what you are asking is, should maybe number 1 above influence number 2? The answer is yes...but there will be a new issue related to that for your programming...which I explain below, related to Contact Symbols...

By the way, the two SignSpelling Rules for writing individual signs, mentioned above in number 1, are on these web pages:

SignSpelling Rule 1: Write the Position of Contact


SignSpelling Rule 2: Every Sign Has A Center

When writing individual signs, the Position of Contact is the center of the sign. If there is no Position of Contact in a sign, then the beginning handshape is the center of the sign, and the arrows relate to it, in a pinwheel around the beginning handshape. So this is the page you should be looking at...it is a great summary:

SignSpelling Rule 2: Every Sign Has A Center

and then these web pages are very helpful too, showing the process of how to write an individual sign:


Later, when placing that completed sign in a sentence, the placement of that completed sign follows a different set of centering rules for sentence construction, related to role shifting and the fact that sentences are based on a Center Lane, a Right Lane for weight shifts or placement to the right, and a Left Lane, for weight shifts or placement to the left...

Centering Signs in Sentences
If the sign has a Head or Shoulder LIne, the Head or Shoulder Line creates the center point for the sign in one of three Lanes...

But your question, Steve, is asking about signs that do NOT have Heads or Shoulder Lines...I believe you are asking...Could we center those signs in the Lanes by the Position of Contact that was used to center the sign for the original writing of the sign?

The answer is yes, BUT...you cannot base that on the existance of a Contact Symbol!!

Because Positions of Contact are working so beautifully for us, that we don't need single Touch Contact Stars as much now, because when we write the two hands close to each other, so they really look like they are contacting each other by how close they are written next to each other, it takes away the need for the single Touch Contact Star, and so more and more writers are eliminating single Touch Contact Stars when they don't need them anymore. Of course double Touch Contact Stars - what we call Touch-Touch - are very necessary because that is actually a movement, not a position...but the single Touch Stars are starting to go away, and so you cannot base any centering on contact symbols...

So below...delete Contact Symbols in a sign....no centering can be based on a Contact Symbol...

> There could be 4 levels of centering:
> Head or trunk symbols in sign - select head and trunk symbols.
> Contact symbols in sign - select hand and contact symbols.
> Hand symbols in sign - select hand symbols.
> Otherwise - select everything.

So your software will center signs in Lanes first based on the central Head, and if there is no Head, it will center it on the Trunk (shoulder line), and if there are neither of those, then it will center the sign on the hand symbols in the Position of Contact...Here is my re-write:


1. HEAD (the central Head, if there are more than one head from left to right)

2. TRUNK (Shoulder Line and/or Hip Line)

3. HANDS POSITION OF CONTACT (not based on Contact Symbols, but based on the center of the two Hand Symbols grouped together)

4. BEGINNING HANDSHAPE (when there is no Position of Contact) (The Beginning Hand is always at the beginning of the Movement Symbol that pulls the hand in one of 8 directions...The Beginning Hand is at the STEM of the Movement Arrow, and the Ending Hand is at the TIP of the Movement Arrow...so the sign would be centered by the Beginning Hand...

At the moment, in SignPuddle 1.5, we are centering the signs in three lanes based on numbers 1 and 2 above, I believe? But not on numbers 3 and 4 above? It has been good enough and I have been very happy with it, Steve. Thank you for your pioneering work in this area.

If you think you could also center signs that have no head or trunk, on the Position of Contact, number 3 above, that would be a big step forward, and if number 4 above is not possible, that is ok...just getting number 3 would be fantastic...

But these are very minor differences and right now we are able to read the three Lanes very well the way they are centering right now...

You are right that when people follow the SignSpelling Rules for writing individual signs, that the bounding box for each sign is much smaller and more compact - that is so true and a big difference for readers too - very helpful and thank you for working on this from the software angle -

So really, all you have to do is take away the idea of centering based on the Contact Symbol, but instead center it based on the Position of Contact of the two hands together in a unit...

I hope my long-winded answer is helpful -

Val ;-)


On Oct 9, 2010, at 4:46 AM, Steve Slevinski wrote:

> Hi Val,
> I'd like to discuss the way SignPuddle centers a sign?  The center is used to align signs for text layout.
> To determine the center of a sign with an algorithm, select the important symbols and create a smallest possible rectangle (a bounding box) around only those symbols.  This bounding box represents the center of the sign.  The absolute center of the bounding box is the center of the sign.
> I'm currently using 2 levels of symbol detection.  Either there are head & trunk symbols or not.  If there are head or trunk symbols in a sign, only the head and trunk symbols are selected and enclosed by the centering bounding box.  If there are no head or trunk symbols, then all symbols are selected and the absolute center is used.
> The current method is good enough, but I was considering a refinement based on SignSpelling rule #2: "Every sign has a center":
> http://www.signwriting.org/lessons/elessons/less064.html
> There could be 4 levels of centering:
> Head or trunk symbols in sign - select head and trunk symbols.
> Contact symbols in sign - select hand and contact symbols.
> Hand symbols in sign - select hand symbols.
> Otherwise - select everything.
> Try these levels while reading SignSpelling Rule #1, "Write the position of contact":
> http://www.signwriting.org/lessons/elessons/less063.html
> You can see that a well written sign has a smaller centering bounding box than a poorly written sign.
> I believe this new centering algorithm can improve text layout for both vertical and horizontal writing.
> Regards,
> -Steve

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