Study On Thermal Infrared Data (TASI) Pretreatment And Mineral Information Extraction Method

Thermal infrared emission spectroscopy can detect and identify rock-formingminerals Si-O bond vibration spectral characteristics，and can be used to identifywater-free rock-forming minerals, which is an effective complement to the visibleand reflection infrared remote sensing object recognition. TASI is a Canadian-developed airborne thermal infrared hyperspectral sensor within the range of8-11.5um have32bands. This paper carried out TASI applied research from threeconducts, the atmospheric correction, temperature and emissivity informationseparation, quartz and Calcite information extraction method based on emissivityspectra.In the atmospheric correction, use the MODTRAN simulation of atmosphericradiation transfer model to calculate the atmospheric transmittance, atmosphericupstream radiation and downstream radiation. At the same time, uses AAC algorithmwhich is a method based on TASI data itself to calculate atmospheric transmittanceand atmospheric path radiation. The results show that the upstream radiation anddownstream radiation values have the same magnitude, and therefore TASIatmospheric correction must also eliminate the effects of upstream radiation anddownstream radiation.In terms of the temperature and emissivity information separation, use thetraditional method of the TES algorithm. By resample167spectral bands of rock, soil,vegetation and other surface features from JHU spectral library to TASI’s32bands,reconstruct the εmin-MMD empirical relationship for the whole TASI bands, theRMSE is only0.0126. The results of pretreatment method for error correction andinformation separation between8-11.0um are satisfactory. The minerals’ characteristicabsorption peak positions and spectral shape of emissivity spectral are highlyconsistent with the standard spectrum, which meet requirements of single diagnosticmethod based on the absorption feature parameters for mineral mapping data.However, error correction and emissivity separation between11.0-11.5um are stillneed to be improved. In the extraction of mineral information, use TASI emissivity data （ε8+ε9）/（2-ε14）as SiO2index and（ε31-ε14）/（ε31+ε14）as Calcite normalized index toextracted calcite and quartz distribution in Liu-Yuan region which are of greatsignificance for discovering skarn, hydrothermal alteration zones.