You may have found out by now but for anybody else. The base plane and origin for an assembly is in a plane against the bottom of the model where the bottom would be resting on a XZ plane. Secondly it chooses the XZ geometric center of the assembly for the origin then place the model on the target as if it were the ground. The model cannot go thru the target or ground. If you arrange things so the model is on the wall it cannot go thru the wall.
Also there is some shifting of the model on the screen as the target gets near the edge and corners of the screen. So you have to keep the target near the center. It almost looks like the model is sliding around on ice as it get near the edge of the screen.
I wish it would use the origin you use in Solidworks. Then you could have things go into the ground. such as oil drilling equipment. and then turn off the darn shadow. I really want to place the target on the outside of a structure and have model superimposed over it, allowing it to protrude into the structure. But because of all the limitation the AR part of edrawings it is nothing more than a cheap gimmick. It really has potential to be really useful but it is still feels very much beta to me.
The other major limit is the size your model can be and still have the camera be able to see the target. Sure you can scale the target up 400% and then scale your model down 25% so it shows at real size again then you can stand a little further away. the camera can only be about 4ft away before it has a hard time seeing the 80mm target. The example the tractor is very misleading. It is modeled at the size of a toy. There needs to be a way to have different sized targets and not just a 80mm one. It would be nice to have something fill a room. Where a target could be placed on the wall and project off or into it. Again with no shadow.
The other problem is the focusing of the camera. It always seems to be blurry and every time you move, the picture goes in and out of focus. While it is out of focus it loses the target making the model flash away displaying "you need a marker to see the model in AR". Very annoying.
Hope this clears up some issues with AR on edrawings. I bought edrawing for the iPad to use it as part of an educational training system but turns out I can't because all the limitations and problems. With some messing around I have been able to sort of move the assembly and position a fake origin where I want it but only off the surface of the target. never into it.
Yes, they need to improve upon the AR so that your reference plane can be the floor, not the paper marker. You need to be able to place your object in the world and be able to move/manipulate it without losing the model. I can't even look around the object at various angles, because most of my objects are large pressure vessels, and I can't keep the camera on the marker and look around my pressure vessel at the same time. Some vessels are too large that I can't see the entire model and keep the marker within the camera's view.