ETM+数据DN值转换为热辐射强度问题

<P> 其实是用ETM+数据反演过地表温度过程中的一个问题。地表温度反演首先需要将图像DN值转换为光谱辐射亮度L(λ)：L(λ)=gain * DN + offset,<BR>   或者这个公式另外一种表述是：L(λ)=Lmin(λ)+(Lmax(λ)-Lmin(λ))Qdn/Qmax，Lmax(λ)、Lmin(λ)分别是传感器所能接受到的最大、最小辐射强度，Qdn是图象灰度值，Qmax最大辐射强度对应的灰度值。<BR>   对于Landsat5-TM6来说，gain、offset是常数，Landsat７-ETM+而言，需从头文件中读取。</P>
<P>   对于Landsat/ETM+数据,如何获取这个gain、offset？</P>
<P>      我手头的数据是从网上下载的，Geotiff格式的。例如2000年9月14日的数据，相对应的有一个文本文件，记录了数据相关信息，里头有这样一段：<BR>  GROUP = PRODUCT_PARAMETERS <BR>   CORRECTION_METHOD_GAIN_BAND1 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND2 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND3 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND4 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND5 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND61 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND62 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND7 = "CPF"<BR>   CORRECTION_METHOD_GAIN_BAND8 = "CPF"<BR>   CORRECTION_METHOD_BIAS = "IC"<BR>   BAND1_GAIN = "H"<BR>   BAND2_GAIN = "H"<BR>   BAND3_GAIN = "H"<BR>   BAND4_GAIN = "L"<BR>   BAND5_GAIN = "H"<BR>   BAND6_GAIN1 = "L"<BR>   BAND6_GAIN2 = "H"<BR>   BAND7_GAIN = "H"<BR>   BAND8_GAIN = "L"<BR>   BAND1_GAIN_CHANGE = "0"<BR>   BAND2_GAIN_CHANGE = "0"<BR>   BAND3_GAIN_CHANGE = "0"<BR>   BAND4_GAIN_CHANGE = "0"<BR>   BAND5_GAIN_CHANGE = "0"<BR>   BAND6_GAIN_CHANGE1 = "0"<BR>   BAND6_GAIN_CHANGE2 = "0"<BR>   BAND7_GAIN_CHANGE = "0"<BR>   BAND8_GAIN_CHANGE = "0"<BR>   BAND1_SL_GAIN_CHANGE = "0"<BR>   BAND2_SL_GAIN_CHANGE = "0"<BR>   BAND3_SL_GAIN_CHANGE = "0"<BR>   BAND4_SL_GAIN_CHANGE = "0"<BR>   BAND5_SL_GAIN_CHANGE = "0"<BR>   BAND6_SL_GAIN_CHANGE1 = "0"<BR>   BAND6_SL_GAIN_CHANGE2 = "0"<BR>   BAND7_SL_GAIN_CHANGE = "0"<BR>   BAND8_SL_GAIN_CHANGE = "0"<BR>  END_GROUP = PRODUCT_PARAMETERS <BR>      难道这里头的gian/bias就是公式中的参数？可这“CPF”、"IC"究竟是什么值呢？或者是否还有别的方法确定参数呢？</P>

我可能有这个头文件，回去我帮你找找，因为我的毕业论文就是做的地表温度反演

<P>我现在也在尝试做一些关于城市气候的研究，但是不知入阁起步，不知大家可否给你帮助，把自己做好的方面公开的东西借我看看，<a href="mailtahnuxysx@126.com" target="_blank" >ahnuxysx@126.com</A></P>

楼上的，我正有这方面的想法，我们可以交流，MSN: happyfjy@hotmail.com

<P>我也看过些地温反演的文章，但没有做过！</P>
<P>-------------------------------------------------------------------------------------------------qq群31484599  遥感技术交流会，</P>