Photogrammetric evaluation in clinical genetics: theoretical considerations and experimental results.

As newer mathematical approaches are applied to the field of clinical genetics accurate methods of craniofacial measurement are increasingly necessary. If photogrammetric techniques are to be used certain theoretical and practical issues must be taken into account. Errors due to projection are particularly important, but systematic and random errors must also be considered. We discuss theoretical aspects of projection errors along with experimental measurements. Systematic errors in excess of 20% were found during simulations of typical clinical conditions, although smaller errors were obtained using techniques practical in a clinical setting. Photogrammetric measurements are potentially valuable in the field of clinical genetics but must be used cautiously.