Where is the center point for the Supergalactic coordinate system? I'm trying to build a 3D visualization of the Supergalactic coordinate system and couldn't find any reference to where the center point should be (the Sun, galactic center, the Earth, etc). 

Also I already tried to look into some articles and books, but they only refer to the zero point related to the galactic coordinates.

Where should it be?

Could I use this model as the reference for the Supergalactic Coordinate system, starting to count the SGL (L) and SGB (B) from the yellow line?

It is still unclear to me if (l=137.37 b=0) indicates just the direction of the center of the Supergalactic Coordinates System.

Note: The Sun is being used as the center point.



Plano Galactico translates into Galactic Plane.

Centro Galactico translates into Galactic Center.
According to Wikipedia, the origin of the system is:

The zero point (SGB=0°, SGL=0°) lies at (l=137.37°, b=0°). In J2000 equatorial coordinates, this is approximately (2.82 h, +59.5°).

In the same article there is a recent referred paper on this topic, which explains [The zero point] is one of the two regions where the SGP is crossed by the Galactic plane.

Perhaps you already know this website, which shows many good pictures. I was trying to find a better figure, but I guess you have to push your imagination according to the definition.

EDIT: According to this, SG coordinates are similar to the galactic ones, so that the North Supergalactic Pole is defined in Galactic coordinates, which means that they have the same origin (i.e., the Sun).