Development of Texture Mapping Approaches for Additively Manufacturable Surfaces

manufacturing(AM)technologies have been recognized for their capability to build complex components and hence have ofered more freedom to designers for a long time.The ability to directly use a computer-aided design(CAD)model has allowed for fabricating and realizing complicated components,monolithic design,reducing the number of components in an assembly,decreasing time to market,and adding performance or comfort-enhancing functionalities.One of the features that can be introduced for boosting a component functionality using AM is the inclusion of surface texture on a given component.This inclusion is usually a difcult task as creating a CAD model resolving fne details of a given texture is difcult even using commercial software packages.This paper develops a methodology to include texture directly on the CAD model of a target surface using a patch-based sampling texture synthesis algorithm,which can be manufactured using AM.Input for the texture generation algorithm can be either a physical sample or an image with heightmap information.The heightmap information from a physical sample can be obtained by 3D scanning the sample and using the information from the acquired point cloud.After obtaining the required inputs,the patches are sampled for texture generation according to non-parametric estimation of the local conditional Markov random feld(MRF)density function,which helps avoid mismatched features across the patch boundaries.While generating the texture,a design constraint to ensure AM producibility is considered,which is essential when manufacturing a component using,e.g.,Fused Deposition Melting(FDM)or Laser Powder Bed Fusion(LPBF).The generated texture is then mapped onto the surface using the developed distance and angle preserving mapping algorithms.The implemented algorithms can be used to map the generated texture onto a mathematically defned surface.This paper maps the textures onto fat,curved,and sinusoidal surfaces for illustration.After the texture mapping,a stereolithography(STL)model is generated with the desired texture on the target surface.The generated STL model is printed using FDM technology as a fnal step.

Bidirectional Texture Mapping

Texture mapping is an important technique for high -quality image generation in computer graphics. In this paper, the shortcoming of the traditional texture mapping approaches is analysed and a general bidirectional texture mapping method is proposed. Based on the bidirectional mapping, an algorithm for mapping an image to an arbitrary polygon in 3D space is given.

Bernoulli Embedding Model and Its Application in Texture Mapping

A novel texture mapping technique is proposed based on nonlinear dimension reduction, called Bernoulli logistic embedding （BLE）. Our probabilistic embedding model builds texture mapping with minimal shearing effects. A log-likelihood function, related to the Bregman distance, is used to measure the similarity between two related matrices defined over the spaces before and after embedding. Low-dimensional embeddings can then be obtained through minimizing this function by a fast block relaxation algorithm. To achieve better quality of texture mapping, the embedded results are adopted as initial values for mapping enhancement by stretch-minimizing. Our method can be applied to both complex mesh surfaces and dense point clouds.

Research on Urban Building Parametric Modelling Method Based on CityEngine

With the advancement of technology and the development of cities,urban planning and management methods are also constantly improving.From paper-based assignments to modern digitization,new technologies have enabled more efficient design and management for cities.3D modeling can used to simulate the urban environment,which can assist in urban planning and management.However,large-scale modeling cannot be achieved through existing modeling methods,and there are still some shortcomings in the maintenance of the model.Therefore,this article proposes a Computer Generated Architecture(CGA)parametric 3D modeling method based on CityEngine.Research on expanding and customizing modeling rules to create indoor and outdoor modeling rule templates for buildings and methods for generating urban 3D models have been carried out.The results have shown that the completed model can be displayed on different platforms thanks to parameterized modeling.The model can be modified easily and directly applied to the analysis and decision-making of urban planning schemes.

Method of Direct Texture Synthesis on Arbitrary Surfaces

A direct texture synthesis method on arbitrary surfaces is proposed in thispaper. The idea is to recursively map triangles on surface to texture space until the surface iscompletely mapped. First, the surface is simplified and a tangential vector field is created overthe simplified mesh. Then, mapping process searches for the most optimal texture coordinates intexture sample for each triangle, and the textures of neighboring triangles are blended on the mesh.All synthesized texture triangles are compressed to an atlas. Finally, the simplified mesh issubdivided to approach the initial surface. The algorithm has several advantages over formermethods: it synthesizes texture on surface without local parameterization; it does not needpartitioning surface to patches; and it does not need a particular texture sample. The resultsdemonstrate that the new algorithm is applicable to a wide variety of texture samples and anytriangulated surfaces.

Electromagnetic induction mapping at varied soil moisture reveals field-scale soil textural patterns and gravel lenses

Knowledge of the spatial distribution of soil textural properties is important for determining soil moisture storage and soil hydraulic transport properties.Capturing field heterogeneity without exhaustive sampling and costly sample analysis is difficult. Our objective was to employ electromagnetic induction(EMI) mapping in low apparent electrical conductivity(EC_a) soils at varying soil water contents to capture time invariant properties such as soil texture. Georeferenced EC_ameasurements were taken using a ground conductivity meter on six different days where volumetric water content(θ_v) varied from 0.11 to 0.23. The 50 m × 50 m field included a subsurface gravelly patch in an otherwise homogeneous silt-loam alluvial soil.Ordinary block kriging predicted EC_aat unsampled areas to produce 1-m resolution maps. Temporal stability analysis was used to divide the field into three distinct EC_a regions. Subsequent ground-truthing confirmed the lowest conductivity region correlated with coarse textured soil parent materials associated with a former high-energy alluvial depositional area. Combining maps using temporal stability analysis gives the clearest image of the textural difference. These maps could be informative for modeling,experimental design, sensor placement and targeted zone management strategies in soil science, ecology, hydrology,and agricultural applications.

Layered Textures for Image-Based Rendering

An extension to texture mapping is given in this paper for improving theefficiency of image-based rendering. For a depth image with an orthogonal displacement at eachpixel, it is decomposed by the displacement into a series of layered textures (LTs) with each onehaving the same displacement for all its texels. Meanwhile, some texels of the layered textures areinterpolated for obtaining a continuous 3D approximation of the model represented in the depthimage. Thus, the plane-to-plane texture mapping can be used to map these layered textures to producenovel views and the advantages can be obtained as follows: accelerating the rendering speed,supporting the 3D surface details and view motion parallax, and avoiding the expensive task ofhole-filling in the rendering stage. Experimental results show the new method can producehigh-quality images and run faster than many famous image-based rendering techniques.

Transition Texture Synthesis

Synthesis of transition textures is essential for displaying visually acceptable appearances on a terrain. This investigation presents a modified method for synthesizing the transition texture to be tiled on a terrain. All transition pattern types are recognized for a number of input textures. The proposed modified patch-based sampling texture synthesis approach, using the extra feature map of the input source and target textures for patch matching, can synthesize any transition texture on a succession pattern by initializing the output texture using a portion of the source texture enclosed in a transition cut. The transition boundary is further enhanced to improve the visual effect by tracing out the integral texture elements. Either the Game of Life model or Wang tiles method are exploited to present a good-looking profile of successions on a terrain for tiling transition textures. Experimental results indicate that the proposed method requires few input textures, yet synthesizes numerous tileable transition textures, which are useful for obtaining a vivid appearance of a terrain.

Reality-based generation of virtual environments for digital earth

Digital Earth essentially consists of 3D and moreD models and attached semantic information(attributes).Techniques for generating such models efficiently are required very urgently.Reality-based 3D modelling using images as prime data source plays an important role in this context.Images contain a wealth of information that can be advantageously used for model generation.Images are increasingly available from satellite,aerial and terrestrial platforms.This contribution briefly describes some of the problems which we encounter if the process of model generation is to be automatised.With the help of some examples from Digital Terrain Model generation,Cultural Heritage and 3D city modelling we show briefly what can be achieved.Special attention is directed towards the use of model helicopters for image data acquisition.Some problems with interactive visualisation are discussed.Also,issues surrounding R&D,professional practice and education are also addressed.

New Algorithm for 3D Facial Model Reconstruction and Its Application in Virtual Reality

3D human face model reconstruction is essential to the generation of facial animations that is widely used in the field of virtual reality (VR). The main issues of 3D facial model reconstruction based on images by vision technologies are in twofold: one is to select and match the corresponding features of face from two images with minimal interaction and the other is to generate the realistic-looking human face model. In this paper, a new algorithm for realistic-looking face reconstruction is presented based on stereo vision. Firstly, a pattern is printed and attached to a planar surface for camera calibration, and corners generation and corners matching between two images are performed by integrating modified image pyramid Lucas-Kanade (PLK) algorithm and local adjustment algorithm, and then 3D coordinates of corners are obtained by 3D reconstruction. Individual face model is generated by the deformation of general 3D model and interpolation of the features. Finally, realistic-looking human face model is obtained after texture mapping and eyes modeling. In addition, some application examples in the field of VR are given. Experimental result shows that the proposed algorithm is robust and the 3D model is photo-realistic.

Hardware Assisted Fast Volume Rendering with Boundary Enhancement

In this paper, a new volume rendering method with boundary enhancement is presented. The boundary is extracted and represented by surfaces explicitly. Then, using 3D texture mapping and graphics acceleration hardware, the volume data can be rendered with controllable boundary shading effect almost in real time. Test shows that this method is 4-5 times faster than the previous methods. Moreover, it can also be extended to render the surfaces and the volumetric data together interactively.

Augmented virtual environment: fusion of real-time video and 3D models in the digital earth system

An Augmented virtual environment(AVE)is concerned with the fusion of real-time video with 3D models or scenes so as to augment the virtual environment.In this paper,a new approach to establish an AVE with a wide field of view is proposed,including real-time video projection,multiple video texture fusion and 3D visualization of moving objects.A new diagonally weighted algorithm is proposed to smooth the apparent gaps within the overlapping area between the two adjacent videos.A visualization method for the location and trajectory of a moving virtual object is proposed to display the moving object and its trajectory in the 3D virtual environment.The experimental results showed that the proposed set of algorithms are able to fuse multiple real-time videos with 3D models efficiently,and the experiment runs a 3D scene containing two million triangles and six real-time videos at around 55 frames per second on a laptop with 1GB of graphics card memory.In addition,a realistic AVE with a wide field of view was created based on the Digital Earth Science Platform by fusing three videos with a complex indoor virtual scene,visualizing a moving object and drawing its trajectory in the real time.

Modeling and volume rendering approach of underwater three-dimensional acoustic energy field

The underwater acoustics is primary and most effective method for underwater object detection and the complex underwater acoustics battlefield environment can be visually described by the three-dimensional(3D)energy field.Through solving the 3D propagation models,the traditional underwater acoustics volume data can be obtained,but it is large amount of calculation.In this paper,a novel modeling approach,which transforms two-dimensional(2D)wave equation into 2D space and optimizes energy loss propagation model,is proposed.In this way,the information for the obtained volume data will not be lost too much.At the same time,it can meet the requirements of data processing for the real-time visualization.In the process of volume rendering,3D texture mapping methods is used.The experimental results are evaluated on data size and frame rate,showing that our approach outperforms other approaches and the approach can achieve better results in real time and visual effects.