The video above shows how to fake the tilt shift effect in Adove Premiere, the process is adding gaussian blur with high blur settings, use a feathered mask to select the area of focus. Although this method is simple and easy to use it will not distort the perspective and it is simply a gaussian blur effect with a wide area of focus, I will not be using this method.
Pixar has published a tutorial on how to produce the tilt shift effect in Maya using Mayas camera settings. I will rely on this method as it is more accurate and produces better results.
The process is as follows, create a polygon triangle and create a cluster handle on each vertex, select the vertex then deform the cluster using anim deform menu. Create a locator and snap it to the vertex and make the cluster handle a child of the locator so the the locator can move the cluster and the vertex.
Create and select a pxrcamera, load the camera and a transform locator in the connection editor and connect the locator to the pxrcamera focus.
If done right this should be the result. Using this method there is no need to model everything in miniature models instead normal size assets can be used with this effect to produce miniature look.