The correct recognition of radiant directionality of non isothermal mixed pixel is a precondition to its retrieval of component temperatrues. Based on the local thermal equilibrium and component effective emissivity concept the radiant model of continuous vegetation has been studied. The model shows that the radiant directionality of isothermal mixed pixel is fully dependent on that of whole effective emissivity of pixel

which is a function of component emissivities and the crown construct. For nonisothermal mixed pixel

the component temperatures play important role in adjustment of radiant directionality. The paper studies the relationship between the radiant directionality with leaf facet emissivity

soil surface emissivity

leaves area index （ LAI ） and leaves angle distribution （ LAD ） by Monte Carlo simulated results

it further analyses the whole effective emissivity and radiance increments caused by cave effects. Take the spherical type of LAD as an example

and set the values of leaf facet emissivity and soil surface emissivity to 0.98 and 0.94 respectively

the increment of whole effective emissivity ranges from 0.01 to 0.025 when value of LAI is set to more than 1.0 in nadir direction. When the vegetation and soil system is isothermal with 293K temperature

the radiant brightness temperature increment is more than 0.8K

the maximum is 1.3K caused by cave effects.