OnePlus One has the same property as the Oppo Find 7, it can put multiple images together to form a larger, see the result here.
A user on OnePlus’ forum has taken a number of photos with your phone. The pictures show a quite impressive detail, and you will notice that some of the images have a resolution of 8,160 x 6,120. It is presumed, therefore, that the OnePlus One has a function similar to the Oppo Find 7 which allows to put multiple images together into a single image at 50 megapixels.
More pictures can be seen at OnePlus’ forum here. Note that the user also linking to a post later with additional images. The same user has recorded a short film in 4 k quality, as can be seen below.