线性光谱混合模型是目前应用最广泛的光谱混合模型，但由于遥感观测多分辨率的特点，模型的适用性会受到尺度效应的影响。为探索该模型在不同观测尺度下的适用程度，本文从地物辐射原理出发，通过理论推导微面元辐射通量表达式，得出地物辐射通量除了与端元反射率和面积比有关外，也与天顶角存在显著的非线性关系。因此，在线性光谱混合模型和微面元辐射通量的基础上，推导了更具普适性的积分线性光谱混合模型的表达式，再采用数值模拟的方法，计算了两模型的相对差值Δρ，结果表明Δρ的大小仅与探测单元的半瞬时视场角β有关，并通过实测光谱实验对上述推论进行了验证。研究表明，当β < 13°时，Δρ较小，线性光谱混合模型是积分线性光谱混合模型的一种近似表达形式，β完全可作为确定线性光谱混合模型适用观测尺度的关键依据，并且该模型的适用程度随β的增大而降低。

The Linear Spectral Mixture Model is the most widely used spectral mixing model. Due to the multi-resolution characteristics of remote sensing observations, the applicability of the model will be affected by the scale effect. In order to explore the applicability of the model in different observational scales, this paper starts from the radiation principle of ground objects and derives the radiative flux expression of the ground surface micro-surface features theoretically. The results show that the radiative flux is not only related to the endmember reflectance and the area ratio, there is also a significant non-linear relationship with the zenith angle. Based on the Linear Spectral Mixture Model and the micro-facet radiant flux, the expression of the Integral Linear Spectral Mixture Model is deduced. Then through numerical simulation, the relative difference (Δρ) of the two models is calculated. The analysis results show that Δρ is only related to the semi-instantaneous field of view (β) of the detection unit. The above inferences were verified by actual spectroscopy experiments. The results indicate that when β < 13°, Δρ is smaller. The Linear Spectral Mixture Model is an approximate representation of the Integral Linear Spectral Mixture Model. Besides, β can be used as the key basis for determining the applicable scale of the Linear Spectral Mixture Model, and the applicability of the model decreases with the increase of β.