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This article discusses the measurement of acoustic source radiation patterns with surrounding spherical microphone arrays in the context of acoustic holography. For practical reasons the spherical wave spectrum, which forms the basis for spherical holography, is determined through spherical harmonic transform (SHT) of discrete observations on the sphere. The discrete SHT and its limitations are addressed, particularly with emphasis on spherical harmonic order truncation and angular sampling; the existence and kind of spherical harmonic decompositions for different fundamental angular sampling schemes are summarized and compared for a varying number of sampling points. In conclusion, feasible array configurations for accurate acoustic holography are outlined with respect to numerical accuracy and hardware efficiency.