“…The information can be encoded either by including a linear operator to the measurement model or by forming the prior covariance function as a solution to a stochastic partial differential equation (SPDE). Similar ideas have been previously used, for example, in Kriging [10][11][12][13][14], image processing [15,16,6], Kalman filtering [17,18], and physical inverse problems [19][20][21]. In the machine learning context, the inclusion of linear operators into GP regression models has also been previously proposed.…”