Thanks Alessandro, that's the most likey reason - that we're representing the true dimensions in mm's.

As we've stated, it's not necessary to do this, you can define whatever unit scale you'd like and this will be inherited as the scene unit. Where true dimensions can be useful is when you are attempting to perform measurements using the target, and when combining targets of different sizes. Both cases can be accomplished with a custom scale, but are easier with a true dimension scale.

Also what problems are you seeing w/ the physics at the original scale?

Hi mickbanks,

as David said, you can set the scale as you wish, you are not obliged to stick to the 200x scale of the samples;

As a side note: I believe that the "large" scale finds its origin in the fact that the whole scene is set by taking as reference an ImageTarget which is printed on an A4 paper and taking its size in millimeters (which makes a target about 240 millimeters wide); from then on, the camera settings (near and far clip distances) and in general the overall scene layout also follow such unit of measure and thus such scale.

Maybe a target card is better recognised at 200 x  or video resolution on the video Sample holds a better viewing resolution but I juest don't get why they'd

scale to 200 x    but I still sorta feel 1x1 is much better  to run  with as the original Unity 1:1 unit. as so many users get confused pulling in 3D models etc..  

I normally create a simple cube primitive to test the scene scale first .. & was blown away at the sample scenes being so big...  

I'll ask, because I'm sure, but yes you can set whatever scaling you'd like.