本文選題：真實感　切入點：人臉模型調(diào)整　出處：《武漢理工大學(xué)》2012年碩士論文

【摘要】：隨著計算機圖形學(xué)技術(shù)的不斷發(fā)展和完善,虛擬現(xiàn)實技術(shù)在影視動畫制作、廣告設(shè)計、游戲娛樂、生物特征識別等方面的應(yīng)用日益廣泛。在這眾多的研究領(lǐng)域中,創(chuàng)建逼真的特定人臉三維模型一直是一個極富挑戰(zhàn)性的課題。由于人臉面部特征的復(fù)雜性,如何保證模型與人臉的特征匹配,并且對模型實現(xiàn)具有真實感的紋理映射是關(guān)鍵問題,也是本文的研究重點。具體研究內(nèi)容包括： 1.光照模型建立。從真實感圖像繪制流程出發(fā),基于OpenGL光照模型實現(xiàn)了給場景中的模型添加光照效果,提高了三維模型顯示的真實感。通過調(diào)節(jié)場景中環(huán)境光、散射光、鏡面光和發(fā)射光各自的參數(shù)比例,將它們分別計算后疊加起來,形成最終的光照效果。 2.二維人臉特征提取。采用基于膚色的人臉識別算法,先通過相似度計算和閾值分割對圖像進行二值化處理,根據(jù)處理后的結(jié)果判斷出人臉的大致范圍,再通過人工交互界面修正算法局限性導(dǎo)致的人臉范圍判斷失真的地方,最后提取出人臉的輪廓及特征信息。 3.三維模型調(diào)整。提出了基于比例變換的模型調(diào)整算法,首先將三維模型從上至下分割成n塊,求出每一塊的橫坐標最大和最小的點,從而計算出該塊的寬度,根據(jù)寬度以及整個模型的高度算出該塊的比例系數(shù)。類似地,求出提取的人臉輪廓每一行的比例系數(shù)。依據(jù)這些比例系數(shù)來插值調(diào)整三維模型上點的三維坐標值,使其與二維人臉輪廓保持一致。 4.紋理圖像到三維模型的映射。為了更具真實感,要保證將紋理圖像上的關(guān)鍵特征與三維網(wǎng)格模型上相應(yīng)的特征位置準確對應(yīng)。本文采取了簡單約束紋理映射的方法來控制三維特征點與二位紋理之間的映射關(guān)系,即兩點定位后計算關(guān)鍵點的位移差值,根據(jù)這個差值改變原來的紋理空間坐標與三維空間坐標的對應(yīng)關(guān)系,以此來實現(xiàn)模型的特征點精確匹配的效果。 基于VC++6.0和OpenGL圖形庫設(shè)計并實現(xiàn)了三維人臉模型的紋理映射系統(tǒng)。該系統(tǒng)能夠?qū)斎氲膯畏四樥掌M行人臉檢測與特征提取,并通過手工修正及自適應(yīng)的模型調(diào)整來得到目標人臉的三維模型,并對其進行了約束紋理映射和光照調(diào)節(jié),使得結(jié)果真實感效果更強。
[Abstract]:With the development and perfection of computer graphics technology, virtual reality technology has been widely used in film and television animation production, advertising design, game entertainment, biometric recognition and so on. It has always been a challenging task to create realistic 3D face models. Because of the complexity of facial features, how to ensure the matching between the models and the features of human faces. It is a key problem to realize realistic texture mapping of the model, and it is also the focus of this paper. The specific research contents include:. 1. The illumination model is established. Based on the OpenGL illumination model, the illumination effect is added to the model of the scene, and the reality of the 3D model is improved. By adjusting the ambient light and scattering light in the scene, the illumination model is constructed. The ratio of the parameters of the specular light and the emitting light is calculated separately and superimposed to form the final illumination effect. 2. Two-dimensional face feature extraction. Face recognition algorithm based on skin color is adopted. Firstly, the binarization of image is processed by similarity calculation and threshold segmentation, and the approximate range of face is judged according to the processed results. Then the artificial interactive interface is used to correct the distortion of the face range caused by the limitation of the algorithm. Finally, the contour and feature information of the face are extracted. 3. 3D model adjustment. A model adjustment algorithm based on proportional transformation is proposed. Firstly, the 3D model is divided into n blocks from top to bottom, the maximum and minimum points of each block are obtained, and the width of the block is calculated. The proportional coefficients of the block are calculated according to the width and the height of the whole model. Similarly, the ratio coefficients of each line of the extracted face contour are calculated. The three-dimensional coordinate values of the points on the 3D model are interpolated according to these proportional coefficients. Make it consistent with two-dimensional face contours. 4. Mapping texture images to 3D models. In order to ensure that the key features on the texture image are accurately matched with the corresponding feature positions on the 3D mesh model, a simple constrained texture mapping method is adopted to control the mapping relationship between 3D feature points and binary textures. That is to say, the displacement difference of the key points is calculated after two points are located, according to which the corresponding relation between the original texture spatial coordinates and the three-dimensional spatial coordinates is changed to achieve the accurate matching effect of the feature points of the model. Based on VC 6.0 and OpenGL graphics library, a texture mapping system for 3D face model is designed and implemented. The 3D model of the target face is obtained by manual modification and adaptive model adjustment, and the constrained texture mapping and illumination adjustment are carried out to make the result more realistic.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TP391.41

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