scholarly journals A Vector Field Texture Generation Method without Convolution Calculation

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 724
Author(s):  
Xiaofu Du ◽  
Huilin Liu ◽  
Hsien-Wei Tseng ◽  
Teen-Hang Meen

In the LIC algorithm process, symmetrical streamline tracing is used to symmetrically convolve the original values of all the primitive values that pass by to obtain the resulting texture. In this process, streamline tracking and convolution consume a lot of computing resources. To generate more expressive textures for vector fields with less time consumption, a novel method named random increment streamline (RIS) is put forward, which can generate streamline textures without convolution calculations. First, the mesh unit filling preprocessing (MUFP) method is presented to transform an undressed irregular grid into a special kind of regular grid named a “texture pixel”, and the point location and interpolation processes of all sampling points in the texture pixels are calculated before streamline tracking. Second, the random increment streamline method is used to generate line integral convolution style textures without any convolution calculations, thus greatly reducing the algorithm’s time consumption. Third, the vector directions at each point in the static vector field are clearly expressed using the periodic cyclic animation method. Finally, several simplifications of the RIS algorithm are discussed, which help to achieve a better visual effect with faster speed. The programming results show that the method is faster and more applicable than the traditional LIC method and provides clearer expression of the vector field.

Author(s):  
Koji Sakai ◽  
Koji Koyamada ◽  
Kazuma Kamisawa ◽  
Akio Doi

Line integral convolution (LIC) is an effective and powerful technique for generating images from vector fields. In the 3D-LIC, it is very important to select an adequate region of interest (ROI) in the vector field. One way for specifying ROI is to use a surface defined in the vector field. Another way is to use a significance map that defines an ROI related value at each point in the vector field. To represent an anisotropic vector field around a vortex center in an understandable way, we introduced a time-oriented significance map. Our technique for specifying ROI is to use a passage-time for a mass-less particle to travel from nearby vortex center to a pixel location. In our technique, what we call “restricted LIC technique (RLIC),” refers to the passage-time buffer before we start the convolution process at a pixel location. The original RLIC technique is 2-D based. In this paper, we extend this technique to 3-D. To confirm the effectiveness of our technique, we use an anisotropic swirl vector field and construct two types of significance maps, a dlstance-oriented map and a time-oriented map. We will show the difference in the resulting images that are generated from these significance maps.


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