A comparison of temporal and spatial unwrapping on a photoelastic isochromatic phase map is discussed. The analytical results show that the two-dimensional Macy’s spatial unwrapping can yield a quite good retrieval if an inconsistency-free isochromatic map is to be treated as is true in most of the photoelastic problem cases. While only temporal wrapped data are provided for the phase retrieving work, the success strongly depends on providing the correct changing ratio between the two (or more) temporal states, (e.g., percentage variation of load or wavelength step). The simulation of an incorrect ratio of the temporal isochromatic work on the accuracy of the retrieving work is performed. Experimental results show that temporal unwrapping error is more easily occurs near a highly stressed zone.