zoarder

Dear All, i hope you all are fine. I am doing my Msc thesis on Urban Heat island modeling. One part of the model i have a calculation regarding LST calculation from Landsat ETM image. I am using mono-window technique. Manually i calculated LST for one pixel and its ok. But the problem is working in Erdas imagine model maker. My algorithm is showing error. My model is as follows in erdas model maker. { -67.355351 ( 1-$n4_memory - $n6_memory ) + ( 0.458606 ( 1 - $n4_memory - $n6_memory ) + $n4_memory + $n6_memory ) * ( $n8_br_t_k ) - ($n6_memory) * 310.46} / ($n4_memory) here , LST = { a (1-C-D) + (b (1-C-D)+C+D) Tb - D Ta} / C where, a = -67.355351 b = 0.458606 C= Ei * ti (Ei is emissivity and ti is transmissivity) D= (1-ti) [1+(1-Ei)*ti] Ta is mean atmospheric temp, 310.46 k (calculated) but this model is giving error, can anyone help me ? regards Muqit Zoarder