doc:  shape distortion as an expanded polinomial
doc:  shape distortion as an expanded polinomial

mapillary/OpenSfM,sunbingfengPI/OpenSFM_Test,sunbingfengPI/OpenSFM_Test,oscarlorentzon/OpenSfM,sunbingfengPI/OpenSFM_Test,sunbingfengPI/OpenSFM_Test,oscarlorentzon/OpenSfM,oscarlorentzon/OpenSfM,sunbingfengPI/OpenSFM_Test,mapillary/OpenSfM,oscarlorentzon/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM,oscarlorentzon/OpenSfM,mapillary/OpenSfM