We study the effect of viewing directions in projection-based multiviewer display systems. Such systems display different images to several users watching a common screen. While different separation techniques have been used in cinema, we are interested in applications that require a more demanding viewing angle and more independent views, such as multisided immersive environment. We compare the luminous efficiency, crosstalk and colorimetric properties of polarization and spectral multiplexing, as a function of the viewing direction. We find that, whereas for spectral separation the crosstalk does not depend on the viewing angle, for polarization separation, the crosstalk increases with the viewing angle due to the depolarization induced by conventional screens.