Well for a stereo system you can't claim 98% accuracy between two distances! I found a presentation where the baseline is given as 75mm: https://intel.lanyonevents.com....
We still don't know what the cameras are, or the focal length, but I'm sure we'll find out eventually. For now we can use: relative accuracy = (Z/(75e-3*900). Note that 900 represents the minimum measurable disparity divided by the focal length in pixels. This turns out to be almost exactly right with respect to Dell's numbers.
So at 3 feet = 0.91cm, we expect around 98.5%. At 15 feet we get around 93%, 20 feet 90% and so on from there. At 30m we're at around 50% precision, not good enough for mapping, but maybe good enough for background segmentation.
I think it was poorly advertised. Stereo imaging is great for high density 3D measurement, but it sucks at long distances unless you have huge baselines. In case you're wondering, satellites use different orbits to get wide enough distances between the shots (kilometer scale baselines). RealSense works well for doing things like background detection - you look for any pixel which has zero parallax or close up work, e.g. face scanning or augmented reality on a tabletop.
Unfortunately what happens when this sort of thing gets released is everyone, rightly, assumes that they can do stuff like measure buildings. In reality, the technology simply doesn't work like that.
The problem is compounded when people complain that it only works in good lighting. Well sure, but how do you think this system works? Intel recently bought TYZX, a 3D imaging company. What was their main product? An ASIC that performs stereo correlation in real time without any drain on the host processor. So we can be 90% sure that this is what's inside RealSense. It's not like the Kinect or the other RealSense camera that projects an IR pattern into the scene. The point here is that stereo matchers require strong signals in order to get good matching accuracy (which pixel in the other image does this pixel correspond to?). If you take a picture with your crappy tablet cameras, it's going to have shot noise, JPEG artifacts (maybe), dark noise and probably the gain is through the roof. All this means it's almost impossible to accurately match pixels between the images so you can't measure distances accurately either.
There's a reason why all the promo shots are taken on bright sunny days!