Abstract: A method of processing a data set including equispaced and/or non-equispaced data samples is disclosed. The method includes filtering of the data, wherein a kernel defined by a probability density function is convoluted over samples in the data set to perform a weighted average of the samples at a plurality of positions across the data set, and wherein a first order regression is applied to the filtered data to provide a processed data output.

Abstract: The present invention provides a method for calculating a corrected substrate height map of a first substrate using a height level sensor. The method comprises: sampling the first substrate by means of the height level sensor with the first substrate moving with a first velocity, wherein the first velocity is a first at least partially non-constant velocity of the first substrate with respect to the height level sensor, to generate a first height level data, generating a first height map based on the first height level data, and calculating a corrected substrate height map by subtracting a correction map from the first height map, wherein the correction map is calculated from the difference between a first velocity height map and a second velocity height map.