1. 刘瑶

4.  Introduction  Method  Experiment results  Summary & future work

5.  Definition of image simulation ◦ generates synthetic images based on the analysis and understanding of imaging acquisition  Application ◦ Evaluation of system specifications ◦ Test of processing facilities ◦ Test-bench for future algorithm development ◦ Cost-versus-quality trade-offs Image simulation Mid-infrared absorption bands Purpose

6.  Simulation tools ◦ DIRSIG (The Digital Imaging and Remote Sensing Image Generation Model) Spectral range: 0.3 - 20 μm region Types of imagery: multi- and hyper-spectral passive systems, polarimetric imagery, radiative transfer in littoral waters, and active LIDAR systems source ： http://dirsig.blogspot.com/2011/02/ scene-building-with-blender.html

7.  Simulation tools ◦ EeTes (EnMAP end-to-end Simulation)  Spectral range: VNIR & SWIR ◦ PICASSO (Parameterized Image Chain Analysis & Simulation SOftware)  Spectral Range: visible to near-infrared(VISNIR) & TIR  Summary ◦ Image simulation in mid-infrared regions is rarely discussed, especially the absorption bands.

8.  Applications of mid-infrared regions (3-5 μm) ◦ Sensitive to high temperature objects(fire, active volcanoes etc.)  Mid-infrared absorption bands ◦ Fundamental research on these two special band to make preparation for mid-infrared simulation. Image simulation Mid-infrared absorption bands Purpose

9.  Image simulation chain ◦ Surface scene simulation is basis for other two processes. ◦ Solar radiation is absorbed and less will reach the ground and be reflected.  Question ◦ whether the reflected part of surface radiance can be neglected ? ◦ what factors affect the surface radiance composition ?  study bands: 2.7 &4.3 μm Surface scene simulation Atmospheric simulation Sensor hardware simulation Image simulation Mid-infrared absorption bands Purpose

10.  ground radiance simualtion ◦ atmospheric transfer model MODTRAN (MODerate resolution atmospheric TRANsmission) ◦ MODTRAN can simulate the absorption effects of atmospheric molecules to the solar radiation.  Simulation outcome ◦ Total surface radiance (represented by Rt)  Reflected radiance ( represented by Rr)  Emitted radiance (represented by Re)  Rt = Rr +Re ◦ Evaluation index: Rr / Re

11.  Input parameters atmosphere type mid latitude summer/winter aerosol typeurban visibility50 kilometers solar zenith angle30° view zenith angle30° relative azimuth angle90° surface temperature300K/272.2K gas concentration (H 2 O,O 3,CO 2 ) default values sensor altitude1m surface altitude0

12.  surface features  assume all features are lambert in simulation. Type of objectsName vegetation conifer deciduous grass soil sandy loam brown fine sandy loam brown loamy fine sand water sea water distilled water

13.  Spectral reflectance (from JHU spectral library) The reflectance of soil is relatively higher than vegetation and water

14.  Rr/Re near 2.7μm in summer and winter Temperature & reflectance have impacts on surface radiance compositon in mid-infrared absorption bands

15.  Rr/Re near 4.3μm in summer and winter The result is similar to that in 2.7 μm regions

16.  Ratio of Rr to Re of the band ◦ assumption: square-wave spectral response function  Response equals 1 within the band  Response equals 0 outside the band

17.  Rr_b/Re_b in 2.7 & 4.3 band The result in bands is consistent with that in wavelengths.

18.  Summary ◦ Temperature and reflectance of surface features both contribute to the surface radiance composition. ◦ Whether the reflected radiance can be neglected in surface scene simulation relates to the expected accuracy of simulation. For example, if a 10 percent of error is allowed, the reflection of soils, water and vegetation can all be neglected.

19.  Further work ◦ More factors need to be involved: water vapor contents, BRDF, etc. ◦ Reflectance data of surface features should be expanded. ◦ In-situ validation: field measurements of reflected and emitted radiance. ◦ Simulation is working with the sensor. Since the proportion changes with the wavelength, for specific sensor, the surface composition analysis also depends on the bandwidth.