Features of the 3D Collaborative Engine
Real-time Multiresolution Modeling Progressive Transmission
Based on collapsing triangle edges: Each edge collapse causes two adjacent triangles to be eliminated, while each edge split causes two triangles to be inserted Supports progressive transmission of geometric models over networks Useful in the visualization of large and detailed geometric models or in the walkthrough of a distributed virtual environment over networks

 

Resolution Refinement Enables the selection of an optimal resolution of a geometric model to meet the budget limits or other constraints of the user's applications

 

 

Handling of Deformable Objects
	Real Time Rendering Accelerates the rendering process by generating polygon models and refines their resolution incrementally without referring to the defining equation of the parametric surfaces Two techniques are fundamental to our method: - incremental model updating - resolution refinement

 

NURBS Stream In the NURBS Stream, NURBS models are progressively transmitted. According to the dynamic view of the client, records are selectively sent so that visible polygons are displayed first. In the demonstration, transmission speed is lowered for better illustration.   Progressive Transmission In the Progressive Transmission, polygon and texture are transmitted progressively. For the visibility, polygon and texture representing the visible surface would be transmitted in a higher priority. And for the level of detail, model at lower resolution in which its texture is with lower color depth, would also be used to save transmission time.

Video

This video clip shows how the model and texture data are transmitted progressively. The background is the texture being transmitted. Each white rectangle on the texture represents the texture coordinates of a polygon. The model being transmitted locates in the upper-left corner. Stream information is shown in the upper right corner:-- Detail: how detail of the model is being rendered. Default is 10 (max. detail) Polygons: No. of polygons rendered Records sent : No. of records sent from server Speed: Transmission speed of the stream

 

View Dependent Rendering

By applying the same technique as view-dependent transmission, we can perform fast back face culling on rendering. In this video clip, we show the performance of view dependent rendering by a wireframe model. The model is transmitted first, and the rendering mode is then changed to wireframe mode to show how the back faces are culled.

Video

 

NURBS Deformation In the NURBS Deformation, incremental polygon model updating algorithm is used. By making use of pre-computed deformation coefficient, we can deform NURBS models with high performance. Both the visible polygons inside and outside the deformation region are sent in the same priority.

 

The follow features are illustrated in the video: Deformations of single control point Deformations of multiple control points During transmission, it deforms client's model and updates the server's model in real time

Video

Video

This video clip demonstrates a modified polygon selection algorithm. Visible polygons within the deformation region are sent with a higher priority. Visible polygons outside the deformation region are not ignored. They are sent with a lower ratio, e.g. 1:8 to that of those inside the deformation region. Before the model is refined, we deform the model. Polygons within the deformation region are sent first. The texture window in the lower right corner shows the refinement is concentrated at the center, which is the deformation region.

 

 

Area-of-interests (AOI) During run-time, some far-away objects (shown in the red brackets) are progressively downloaded from the server according to the area-of-interests (AOI) of the client.

 

 

Motion Prediction for Moving Objects Extrapolates future position of moving objects Minimizes the network bandwidth consumption

 

 

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