I see the post here for the solution https://developer.vuforia.com/forum/hololens/sample-has-no-stable-tracking and confirm it since I was testing and didn't pay that much attention to the performance (stable of the tracking).
Recently, my project need to use target image on HL for tracking and I did try it with the suggestion. Sizes of print out same as size in Unity and target when upload. However, , if the HL keep looking at the image, the tracking is shifted a bit and then it came back (Y is incorrect), kind of unstable. Is there a way to improve it.
I already turn on extended tracking and I am using vuforia 6.2.10 with Unity 5.6.
The image size that I am using is around 0.0565meter x 0.04725 meter. I then readjust the size to Letter size still no luck, it tracked at the first look and then if the HL keep looking at the image, I see it shifted (Y is incorrect) and then came back.
Any suggestion how to fix it would be very much appreciated.