From their site:
The International Stereoscopic Union (ISU) was founded in 1975 and is the only international 3D association in the world.
3D-Photography, 3D Video Imaging, Computer Stereo, Digital Stereo Projection, Holography, Virtual Reality and all other stereoscopic photography techniques are used by members of the ISU.
Although the ISU caters mainly to the 3D amateur photographer, the ISU also has much to offer to members who are professional stereo photographers and cinematographers, as well as to those who are involved in the scientific aspects of the stereoscopic image.
Stereoscopy – the publication of 3D image-makers
The quarterly Journal of the ISU, Stereoscopy – the publication of 3D image-makers, is circulated to all members and is considered to be an important item keeping the membership up-to-date with the Arts and Technology of 3D Imaging.