Hello ashalota,
I agree with JMR, you should manually resize the bounding box to the area of interest before building dense cloud and completing further processing steps. When building DEM and Mesh I also suggest to use Extrapolated option in the interpolation field in order to create the model without holes extended to the sides of the bounding box.
The default size and orientation of the box depends on the tie points distribution. In your project the box contains about 90% of all tie points, while other points are spread in space without any considerable density.