Coding of animated 3-D wireframe models for internet streaming applications: methods, systems and program products

• US 6,947,045 B1
• Filed: 07/19/2002
• Issued: 09/20/2005
• Est. Priority Date: 07/19/2002
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Ostermann, Jörn, Varakliotis, Socrates
• Primary Examiner(s): Nguyen, Phu K.
• Application Number:
  US10/198,129
• Time in Patent Office: 1,159 Days
• Field of Search: 345/473, 345/474, 345/475, 345/619, 345/418, 345/419
• US Class Current: 345/473
• CPC Class Codes: G06T 9/001 Model-based coding, e.g. wire frame
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

A 3-D wireframe model expressed in terms of nodes and vertices receives a 3-D video or like signal representative of a scene expressed in terms of a reference model, I frames and P frames. A DPCM coder takes advantage of the temporal correlation of the displacement of each vertex along every axis in the 3-D space. The 3-D signal is a set of non-zero displacements of all vertices and all nodes (s_l[n, v]) at time t_l. The decoded set (animation frame) of the previous instance is used as the predicted value (s_i-l[n, v]). The prediction error e_l[n, v], i.e. the difference between the current displacement set and the predicted one, is computed and quantised (e_l[n, v]). Finally, the quantised samples are entropy coded (c_i[n, v]) using an adaptive arithmetic coding algorithm to handle the unknown data statistics. The predictive scheme described above prevents quantization error accumulation. A DPCM decoder first decodes arithmetically the received samples (‘e’ [n, v]) and computers the decoded samples (s_i′ [n, v]).

Claims

1. A method of coding 3D animated wireframe models suitable for Internet streaming applications, comprises:

a) providing a 3D signal representative of a scene expressed in terms of a reference model, I frames and P frames to a 3-D wire frame model expressed in terms of Nodes and Vertices;

b) generating a Node Table listing all IndexFace Set nodes in the scene; and

c) forming a NodeMask and Vertex Mask in bit form for the 3D wireframe model.

2. The method of claim 1 further comprising:

d) setting bits in the NodeMask denoting the nodes in the scene to be animated.

3. The method of claim 2 further comprising:

e) for Nodes set in the NodeMask, setting bits in the VertexMask deniting the vertices in the node to be animated.

4. The method of claim 3 further comprising:

f) transmitting these Masks for every frame.

5. The method of claim 3 further comprising:

g) transmitting these Masks only if they differ from those of the pervious frame.

6. The method of claim 3 further comprising;

h) generating an output signal from the wireframe model which is a set of non-zero displacement of all vertices and nodes at time [t_l].

7. The method of claim 6 further comprising:

i) generating a predicted value from the previous output signal [t_i].

8. The method of claim 7 further comprising:

m) calculating a prediction error signal based upon the output signal and the predicted value.

9. The method of claim 8 further comprising:

n) quantizing the prediction error signal as quantized samples.

10. The method of claim 9 further comprising:

o) entropy encoding the quantized samples using an arithmetic coding algorithm.

11. The method of claim 10 further comprising:

p) packetizing the encoded quantized samples in an RTP format for Internet streaming applications.

12. The method of claim 6 further comprising

j) generating a predicted value from the previously ccoded output signal [t_i−

l].

13. The method of claim 6 further comprising:

k) generating a predicted value from the previously coded output signal at time t_l.

14. The method of claim 6 further comprising:

l) generating a predicted value from the previously decoded 3D wireframe model.

15. The method of claim 1 further comprising:

q) arithmetically decoding the quantized samples; and

r) computing the decoded quantized samples.

16. A system for coding 3D animated wireframe models suitable for Internet streaming applications, comprising:

a) a 3D animated wireframe model expressed in terms of nodes and vertices

b) receiving apparatus, which receives a 3D signal of a scene including animation at the wireframe model;

c) an encoder which receives output signals from the wireframe model, the output signals indicative of the non-zero displacements of nodes and vertices at time [t_l]; and

d) the encoder computing, quantizing and arithmetically encoding the prediction error signal as quantized samples.

17. The system of claim 16 further comprising:

e) packetizing apparatus which packetizes the quantized samples for Internet streaming applications in the RTP format.

18. The system of claim 17 further comprising:

f) decoding apparatus which arithmetically decode the prediction error samples and computes the coded samples.

19. A method for coding 3D animated wireframe models suitable for Internet streaming applications, comprising:

a) expressing a 3D animated wireframe model in terms of nodes and vertices

b) receiving a 3D signal of a scene in P and I frames including animation at the wireframe model;

c) receiving output signals from the wireframe model, the output signals indicative of the non-zero displacements of nodes and vertices at time [t_l]; and

d) computing, quantizing and arithmetically encoding the prediction error signal as quantized samples.

20. The method of claim 19 further comprising:

e) coding of P frames using the previous frame as a reference.

21. The method of claim 19 further comprising:

f) coding of P frames using the previously decoded and reconstructed wireframe at the decoder as a reference.

22. The method of claim 19 further comprising:

g) coding of I-frames using the reference model as a reference.

23. The method of claim 19 further comprising:

h) decisioning of coding I or P frame depending on network loss as estimated by an encoder or as requested by a decoder.

24. A medium, executable in a computer system, for coding 3D animated wireframe models suitable for Internet streaming applications, comprises:

a) program instructions providing a 3D signal representative of a scene expressed in terms of a reference model, I frames and P frames to a 3-D wire frame model expressed in terms of Nodes and Vertices;

b) program instructions generating a Node Table listing all IndexFace Set nodes in the scene; and

c) program instructions forming a NodeMask and Vertex Mask in bit form for the 3D wireframe model.

25. A medium, executable in a computer system, for coding 3D animated wireframe models suitable for Internet streaming applications, comprising:

a) program instructions expressing a 3D animated wireframe model in terms of nodes and vertices

b) program instructions receiving a 3D signal of a scene in P and I frames including animation at the wireframe model,

c) program instructions receiving output signals from the wireframe model, the output signals indicative of the non-zero displacements of nodes and vertices at time [t_l]; and

d) program instructions computing, quantizing and arithmetically encoding the prediction error signal as quantized samples.