how to randomly select points from a layer

[livejiang]

hi all,

    I want to feed an image to a pre-trained model(eg.vgg16), then up-sample some convolution layers in the network to the same size with the original image. 

    Next, I want to randomly sampled some points in the up-sampled layer and use each point as a single training point in a new regression network.(as described in this paper: http://www.cs.cmu.edu/~aayushb/marrRevisited/)

    My question is that is there any method in caffe that I can do the random sampling as a layer? so I can concat the pre-trained layer and my newly add regression layer as a whole.