1. A method for generating a continuous rock type distribution map characterizing in-ground rock types from measurement-while-drilling data in a mining environment, comprising: drilling holes at a plurality of selected locations within a region of interest; collecting measurements-while-drilling, the measurements comprising penetration rate, and at least one of pull down pressure and rotation pressure; determining, with a processor, from the collected measurements a discontinuous rock type distribution map comprising an array of characteristic measures indicative of rock hardness at various drilling depths in the drill hole locations; generating a continuous rock type distribution map from the discontinuous rock type distribution map by: applying the discontinuous rock type distribution map to a Gaussian process with a selected covariance function to generate a Gaussian process model with optimized hyperparameters; sampling the Gaussian process model by performing Gaussian process regression at a selected spatial resolution within the region of interest; and applying boundary detection to rock hardness output data obtained from the sampling of the Gaussian process model to identify the distribution of at least one cluster of rock type within the region of interest, the boundary detection based on received hardness data between at least a first rock type and a second rock type; and including the detected boundaries in the continuous rock type distribution map.