基於圖形處理器之即時熱影像模擬

Abstract

本論文針對熱式影像為目標，提出一套基於圖形處理器之即時熱影像模擬演算法。我們從熱力學定律中推導出的熱傳遞模型，藉而模擬真實的熱式影像。由於傳統的熱模擬注重精密的數值計算，模擬的過程往往花費了過多的時間。因此，我們建立了簡化後的熱傳遞模型，並使用有限元素法來描述物體的動態熱能，最後藉由圖形處理器的平行運算能力加速模擬流程，輸出即時擬真的熱影像。其中，我們以Phong反射模型為主模擬熱輻射的變化，並以較少的儲存空間計算均勻材質實心物體的熱傳導過程，以圓柱體受風力的熱對流影響簡化時寄物體的複雜邊界。最後，我們將比較實驗結果，分析出模擬過程中最合適的各項參數。

The goal of this thesis is to propose an efficient framework for real-time thermography simulation. Since our purpose is not fully physical simulation but visually correct thermographic view, we propose a plausible illumination method for approximation of heat transfer where radiation, conduction and convection are all included. We use Phong illumination model to simulate radiation since indirect reflection can be ignored with low temperature difference. For simulation of conduction, we construct less 2D textures to substitute a large-sized volumetric 3D object to reduce computational complexity of heat propagation. To simulate convectional effect, we simplify the shapes of objects into cylindrical case and apply the formula of heat transfer from a cylinder in cross flow. All of these methods are able to be accelerated by GPU-based rendering which synthesizes realistic thermal images of a virtual environment in real-time.