3D Digitalization And 3D Printing Reproduction Method For Oil Paintings

Oil paintings are reproduced primarily for decoration, promotion, dissemination, and reference. Reproductions have high value and great market demand, especially because the originals are difficult for ordinary consumers and art learners to obtain. High-fidelity reproductions are becoming increasingly popular. Currently, high-fidelity reproduction of oil paintings is achieved mainly through two methods, namely, manual copying and printing. Manual copying with oil paints often produces real and stereoscopic perception and feel. However, this process is time consuming, and the painting quality largely depends on the artist’s painting skill. And the printing methods including offset printing, digital inkjet printing and screen printing. Offset printing and digital printing achieve high-fidelity replication of oil paintings visually, yet they are unable to replicate the feel of paintings. Screen printing cannot produce reproductions that are consistent with the originals given the unevenness and height of the paint. Moreover, paint thickness compensation in screen printing cannot achieve consistency with the originals in terms of stroke thickness, and its procedures are complicated.In this thesis, digital photogrammetry is used for 3D reconstruction of the originals. After layering the 3D model, a UV curable inkjet printer is chosen as a 3D print device for stereoscopic oil paintings. The main research content of this thesis include:1. Photogrammetry-based 3D reconstruction of oil paintings. The 3D reconstruction and digital representation of oil paintings mainly includes two aspects: 3D geometric information recovery of oil painting surface and color rendition of oil painting. Photogrammetry can acquire a digital 3D model of the surface geometrics of an oil painting, restore the color image and plane geometry of the painting in the form of orthophotomap, and implement the 3D digital representation of color in the painting.2. Layering of the 3D model for oil paintings. For any type of 3D printing, a digital 3D model is imported into a printing device only when its data are layered. In layering, the 2D cross-sectional profile of each layer is obtained with a series of planes that intercept a 3D solid model, thereby making the model a 2D one. Contour points on the edge of the triangulated irregular network(TIN) are obtained from Point Z of the TIN 3D model using the interpolation and arranged in order; this process is called contour tracing. Hypsometric tinting and model rendering are implemented with different contours. On the basis of the obtained hypsometric tints and contour plots, threshold-based image segmentation is implemented by extracting and converting the layered section images into vectors.3. 3D printing and quality control of oil paintings. Quality control is explored from a series of print parameters of the UV printer, such as the nozzle, the ink layer(s), and color gamut. With the use of the 2D printer, the 3D rugged surfaces of oil paintings are printed by stacking layers of the UV ink. The resultant orthographic projections of the paintings are printed onto the 3D surfaces of oil paintings, and the entire process of copying the oil paintings is completed.In this thesis, a 3D reproduction method for oil paintings is demonstrated experimentally. Digital photogrammetry is used for 3D modeling of oil paintings. Modeling results show that digital photogrammetry can effectively establish a colorful 3D model for oil paintings. The principle of the 3D model for oil painting surfaces is identical to that of DEM. Thus, the model is convenient for contour plotting and hypsometric tinting, and for turning a 2D model into a 3D one through discretization. This stereoscopic reproduction method for oil paintings compensates for the deficiencies of existing reproduction methods and expands the applications of 3D printing. However, modeling accuracy, color rendition, and printing quality of oil paintings require further research.