Three-dimensional visualization method for ocean internal wave vertical flow unstable flow field

Abstract

The invention relates to an ocean internal wave three-dimensional visualization method based on a high-temporal-spatial-resolution unstable flow field, and belongs to the technical field of computer vision and ocean fluid mechanics. According to the method, a GPU texture visualization technology is utilized, an internal wave data processing and feature extraction method is provided for vertical flow characteristics of ocean internal waves, and complex dynamic behaviors of the ocean internal waves in an unstable flow field are accurately displayed by highlighting a vertical velocity component W. Compared with a traditional method, the method has the advantages that the spatial and temporal change of high-resolution internal wave data can be reflected more truly, and the vertical flowing characteristics of ocean internal waves in a three-dimensional space can be clearly visualized. The technology is suitable for influence analysis of marine ecological and physical processes and artificial object motion trails, and helps researchers to deeply understand the influence of internal waves on marine fluid motion.

Description

Technical Field

[0001] This invention is based on high spatiotemporal resolution unsteady ocean internal wave data and is aimed at the field of computer visualization of unsteady ocean flow fields, efficiently and accurately displaying the characteristics of three-dimensional visualized ocean internal wave vertical flow. Background Technology

[0002] In physical oceanography, the density of ocean fluids varies with depth, temperature, and salinity, affecting vector factors such as flow velocity. Internal ocean waves are wave phenomena generated at the interface between two fluids of different densities, often occurring in the deeper layers of the water. Within this region, significant vertical changes occur in ocean currents. Internal ocean wave data in unsteady flow fields include vertical flow fluctuations in the internal wave velocity component W, leading to drastic changes in the water's vertical direction. The disturbance of the internal wave vertical velocity causes temporal and spatial variations in the velocity distribution structure of the ocean, thus altering the trajectory of moving objects. The amplitude of internal waves is generally much larger than that of surface waves, and these fluctuations do not affect the sea surface, making their propagation difficult to observe. The existence of their vertical velocity W has significant impacts on marine ecosystems, physical processes, and man-made objects (such as submarines and offshore platforms).

[0003] A three-dimensional visualization method for unsteady vertical flow fields of ocean internal waves is proposed. This method processes data to visualize the vertical flow of internal waves in a visual manner, offering good interactivity. It can be applied in the marine field to meet diverse needs of marine operations. This patent utilizes GPU-based texture visualization technology to visualize the vertical flow phenomena of ocean internal waves in unsteady flow fields. Summary of the Invention

[0004] Traditional methods for visualizing ocean current fields often rely on ordinary two-dimensional and three-dimensional ocean data. This type of data typically contains only two data channels (east-west velocity U and north-south velocity V) and does not prominently represent the vertical velocity W. Therefore, it is difficult to effectively represent the complexity of vertical flow of internal ocean waves and their flow characteristics in the three-dimensional space of an unstable flow field. Furthermore, it lacks precision in representing the dynamics of vertical flow of internal ocean waves in an unstable flow field and cannot fully demonstrate the complex motion of internal waves in such a field.

[0005] This invention utilizes GPU texture visualization technology and selects high spatiotemporal resolution unsteady ocean internal wave data to validate the algorithm. When visualizing ocean internal wave data in an unsteady flow field, parameters are adjusted to fully consider the characteristics of ocean internal waves, ensuring a true reflection of the original data. To fully demonstrate the vertical flow characteristics of ocean internal waves, the W-axis vertical velocity component is highlighted for feature extraction of internal wave data in the unsteady flow field, detecting regions with high velocities and significant upwelling and downwelling ocean internal wave phenomena. Furthermore, a transfer function is used to map the flow field velocity features to color and opacity, thereby emphasizing the vertical flow characteristics of internal waves.

[0006] 4. The beneficial effects of this invention are as follows:

[0007] Based on high spatiotemporal resolution unsteady ocean internal wave data, this invention effectively solves the problem of unclear visualization effects of high-resolution ocean internal wave data. By employing high spatiotemporal resolution unsteady ocean internal wave data and combining it with GPU technology for 3D visualization, the complex dynamic changes in the ocean internal wave flow field can be effectively displayed. This high spatiotemporal resolution visualization technology helps researchers more accurately understand the behavior of ocean internal waves and their impact on fluid motion, making the visualization of internal wave vertical flow characteristics more intuitive and facilitating the identification and analysis of key influence regions of internal waves in unsteady flow fields. Attached Figure Description

[0008] Figure 1

[0009] 6. Brief description

[0010] Figure 1 A flowchart of an internal wave visualization technique based on texture and particle methods is presented. The process consists of seven core steps, in the following order: (1) loading an unstable flow field onto a texture; (2) performing particle tracking and scattering using a noise function; (3) sampling the velocity of the internal wave data; (4) interpolating the velocity in the flow field texture; (5) generating streamlines using the Runge-Kutta method; (6) adding lighting effects using the Blinn-Phong model; and (7) finally calculating the velocity field and completing color mapping using a transfer function. This process systematically realizes the generation process from raw data to the final visualized image. 7. Detailed Implementation

[0012] (1) Load high spatiotemporal resolution ocean internal wave data as flow field data texture, and sprinkle particles (virtual points, hereinafter referred to as particles) in the flow field.

[0013] (2) The motion simulation of particles is realized through the GPU Transform Feedback mechanism. The particle distribution in the flow field region is realized by using a noise function. The initial position of the particles in the flow field is randomly selected so as to uniformly cover the entire range of the ocean flow field data used.

[0014] (3) A velocity sampler is used to sample the three velocity components (U, V, and W) in the ocean internal wave velocity field based on the particle's current position. The motion of each particle is affected by the three velocity component attributes of the ocean internal wave velocity field. Particle tracking technology is used, and a velocity sampler is used to sample the three velocity components (U, V, and W) in the ocean internal wave velocity field based on the particle's current position to obtain the particle velocity information at that position.

[0015] (4) The velocity of effective particles in the sampled flow field texture is interpolated using texture visualization technology, including two-dimensional layer-by-layer velocity interpolation and three-dimensional frame-by-frame velocity interpolation. This better smooths the velocity changes and ensures a smooth transition between textures.

[0016] (5) Streamlines are generated based on particle positions using the GPU's tessellation shader technology. In the GPU's TessellationControl Shader, the particle position is used as the starting point of the streamline. The fourth-order Runge-Kutta integral is used to generate the flow field direction line (i.e., the line in the flow field with arrows indicating the direction, hereinafter referred to as streamline) based on the particle position and the sampled velocity of the particle by performing forward integration according to the effective particles in the current flow field. This expresses the vertical flow of internal waves in the ocean.

[0017] (6) The Blinn-Phong lighting model is used to illuminate the streamlines, so that the streamlines have variations in brightness and shadow in three-dimensional space, thereby improving the spatial perception of ocean waves flowing in the vertical direction.

[0018] (7) The flow field characteristics are mapped to color and opacity based on the velocity value using a transfer function. By adjusting the above variables, the vertical flow phenomenon of internal waves in the ocean current field is highlighted. For high spatiotemporal resolution ocean internal wave data, this patent proposes a method to highlight the characteristics of internal wave vertical flow W by calculating the comprehensive velocity field a: Then, the influence of W is separated and compared with the velocity field b without the influence of the W component: Subtracting ab from the two values ​​highlights the vertical velocity component of the internal ocean wave W in an unstable flow field, and visualizes it as a feature to emphasize the influence of the overall vertical velocity of the internal ocean wave. This allows for the assessment of the vertical flow characteristics of the internal waves in the ocean flow field, highlighting the velocity variations of the rising and falling internal waves.

Claims

1. A three-dimensional visualization method for unsteady vertical flow fields of internal ocean waves, comprising the following basic steps: (1) The motion of particles in a three-dimensional flow field is realized through the GPU Transform Feedback mechanism, characterized in that: The particles are uniformly distributed in the flow field, and the east-west U, north-south V and vertical W velocity component attributes in the ocean internal wave velocity flow field are sampled according to the particle position, the velocity at the position of the particle is obtained, and the state of the ocean internal wave vertical flow is further judged.(2) The flow field direction line (i.e. the line with arrow direction in the flow field, hereinafter referred to as flow line) is generated based on the particle position integration through the subdivision shader technology of GPU, and the characteristics are as follows: in the Tessellation Control Shader of GPU, the position of the particle is taken as the starting point of the flow line, and the three-dimensional flow field is sampled after the coordinates are normalized. The velocity sampler is used to sample the east-west U, north-south V and vertical W three velocity components in the ocean internal wave velocity flow field. The flow line is generated by the fourth-order Runge-Kutta integration, the maximum number of points on the flow line can be controlled by setting the subdivision parameters in the Tessellation Control Shader, and the Blinn-Phong lighting model is used for lighting processing of the flow line, so that the flow line has the change of highlight brightness and shadow in the three-dimensional space, so as to improve the spatial perception of the three-dimensional flow line.(3) The transmission function can be used to map the flow field characteristics to color and opacity according to the velocity value, and the above variables can be adjusted to highlight the internal wave vertical flow phenomenon in the ocean flow field. For high space-time resolution ocean internal wave data, the method proposed in the present application highlights the vertical flow W characteristics of the internal wave, and the comprehensive velocity field Then the influence of W separated out is compared with the velocity without W component influence Subtracting the two, the W vertical component part can be highlighted and taken as a feature to visualize the influence of the entire ocean internal wave vertical velocity, so as to judge the vertical flow characteristics of the internal wave in the ocean flow field and highlight the velocity change characteristics of the internal wave up and down flow.

2. In the three-dimensional visualization method for vertically unstable flow fields of ocean internal waves according to claim 1, the high spatiotemporal resolution ocean internal wave data used is different from the ocean data previously seen, characterized in that: (1) High spatiotemporal resolution unstable field ocean internal wave data has multiple layers, wide water depth, and high spatiotemporal resolution. The number of layers is twice that of ordinary ocean current data, which is greater than the 50 layers of common ordinary ocean data; the depth is greater than the 5000 meters of common ordinary ocean data; and the resolution is much greater than 1 degree of ordinary ocean data, which is high spatiotemporal resolution ocean internal wave data; (2) High spatiotemporal resolution unstable ocean internal wave data contains a velocity component W that can cause vertical flow in the ocean, which has a crucial impact on objects and phenomena in the ocean. An unstable field refers to the chaotic, frequent, and irregular motion of fluids in the ocean, manifested as turbulent or mixed flow. In an unstable field, physical parameters change significantly, the flow field is easily disturbed, and complex motion patterns are generated. The velocity component W in the unstable ocean internal wave data flows vertically, causing drastic changes in velocity in the vertical direction, thereby altering the trajectory of objects. Due to the vertical disturbance of internal waves, the velocity distribution structure in the ocean will experience temporal and spatial fluctuations, thus generating fluctuations in the vertical flow of ocean internal waves.

3. The three-dimensional visualization method for unsteady vertical flow fields of ocean internal waves according to claim 1, characterized in that, In step (2), due to the high propagation speed of ocean internal waves, the vertical flow has a significant impact on objects. The color and opacity of streamlines can be adjusted by using a transfer function to highlight the characteristic region of the vertical flow of ocean internal waves. The velocity characteristics of the vertical flow of ocean internal waves can also be observed by adjusting the particle density and characteristic values ​​of the three-dimensional streamlines in the flow field.

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