This work presents, summarizes and validates a fast, accurate and general measurement and modeling technique to obtain spectral near field data of LED systems in order to improve the optical design process of modern high quality LED systems. It requires only a minimum of goniophotometric near field measurements as well as no time-consuming angularly resolved spectral measurements. The procedure is named physically motivated basis spectra (PMBS) as its main assumption is that each piece of angularly and spatially varying spectral information can be described as the weighted sum of its physical basis spectra such as the individual semiconductors or a phosphor. Based on detailed spectral information regarding the goniophotometric measurement setup, the spectral model is obtained by solving a simple system of linear equations using the obtained near field measurements. The complete process is validated and applied to different state-of-the-art LED systems. The obtained results can be used directly in state-of-the-art ray tracers.