The dual frequency grating projection based on structured light is very important in the phase retrieval for the fusing of the advantages of dual frequency grating, it must satisfy a basic condition to better obtain the phase information. Firstly, the relationship between phase information and height information of object measured is given, and the basic principle of phase retrieval based on dual frequency grating projection is analyzed in detailed. Secondly, the corresponding phase retrieval condition is proposed, that is to say, the high frequency must be at least twice as large as the low f...
