1. A method of enabling touch determination based on an output signal from a touch-sensitive apparatus, the touch-sensitive apparatus including a panel, a plurality of peripheral light emitters and a plurality of peripheral light detectors, the plurality of peripheral light emitters configured to transmit light signals to the plurality of peripheral light detectors, the transmitted light signals defining actual detection lines across a surface portion of the panel between pairs of light emitters and light detectors, the touch-sensitive apparatus further including at least one signal generator coupled to the plurality of peripheral light emitters to generate the light signals, wherein the plurality of peripheral light detectors are configured to generate the output signal, the method comprising: processing the output signal to generate a set of data samples in a two-dimensional sample space, wherein each data sample is representative of an actual detection line, and wherein the data samples are defined by a signal value indicative of detected energy for at least a subset of the actual detection lines and two dimensional values that define the location of the actual detection line on the surface portion; processing the set of data samples to generate a set of matched samples at locations in the two-dimensional sample space, each matched sample samples having an estimated signal value, wherein the matched samples are indicative of estimated detected energy for fictitious detection lines that have a location on the surface portion that matches a standard geometry for tomographic reconstruction, the processing the set of data samples including, calculating the estimated signal values according to a two-dimensional interpolation function and based on the signal values of the data samples; and processing the set of matched samples by tomographic reconstruction to generate data indicative of a distribution of an energy-related parameter within at least part of the surface portion.