Triangle mesh compression

摘要

A computer implemented method of processing elevation mesh data defining a polygon mesh surface to determine an alternative representation of the surface using fewer polygons than in the original representation is disclosed. Initially original elevation mesh data is sub-sampled to generate a low resolution representation of the polygon mesh surface where vertices of polygons correspond to points on a coarser X-Y grid than the original elevation mesh data. Error values indicative of the extent that portions of the surface defined by the low resolution elevation mesh data differ from corresponding portions of the surface defined by the original elevation mesh data are then determined. An alternative representation of the polygon mesh surface is then generated which comprises: low resolution elevation mesh data for the portions of the polygon mesh surface associated with error values less than a threshold value; transition mesh data defining a polygon mesh surface immediately adjacent the perimeter of portions of the surface represented by the low resolution elevation mesh data; and higher resolution elevation mesh data for the remaining portions of the polygon mesh surface.

主权项

1. A computer implemented method of pre-processing data representing a triangle elevation mesh to encode the data in a manner suitable for data compression, the method comprising:
using a computer to: receive elevation mesh data comprising a two-dimensional array of Z values associating points on a regular uniform X-Y grid with a height value or values indicating that no height data is associated with that point on the grid; select groups of data points at positions (x,y), (x,y+1), (x+1,y) and (x+1, y+1) in the array corresponding to pairs of adjacent triangles in the mesh in an order which traverses the mesh; check whether data points selected for encoding are associated with height values; and encode data for a triangle if all the data points selected for encoding are associated with height data by: determining for each data point whether data corresponding to the selected data point has previously been encoded and if not encoding data for the selected data point by storing data defining a vector identifying the position identified by the x and y co-ordinates for the selected data point and the z value associated with the x and y co-ordinates wherein the vector comprises: a vector identifying the absolute position identified by a data point in the case of a first data point of a group of three data points defining a triangle in a triangle mesh; or a vector identifying the relative position identified by a data point relative to the position of previously encoded data identified by other data points in a group of data points in the case of subsequent data points in a group of three data points defining a triangle in a triangle mesh.