# US 2014/0152664 A1 · Method of rendering a terrain stored in a massive database

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- Number: US 2014/0152664 A1
- Document ID: US20140152664A1
- Status: Published application
- Kind: A1
- Application number: 14/093,344
- Filed: 2013-11-29
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Applicants: Thales
- Inventors: Gildas LE MEUR
- Web page: https://patentgrep.com/patent/US20140152664A1

## CPC

- G06T 3/40: Scaling of whole images or parts thereof, e.g. expanding or contracting
- G06T 17/05: Geographic models
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

A method of rendering a terrain stored in a massive database the said terrain rendering being displayed for an observer by a display device comprising at least one graphics card comprising a cache memory, comprises at least: a step of generating several regular grids of different resolution level terrain patches so as to represent the terrain data of the massive database; a step of extracting terrain data from the massive database for several resolution levels, the extracted terrain data forming an extraction pyramid, composed of an extraction window for each level of detail, placed in cache memory. Each window comprises an active zone intended to be displayed, and a preloading zone which makes it possible to anticipate the transfers of data; a step of selecting the patches of the extraction pyramid which contribute to the image; and a step of plotting the rendering on the basis of the selected patches.

## Claims

### Claim 1

A method of rendering a terrain stored in a massive database the said terrain rendering being displayed for an observer by a display device comprising at least one graphics card comprising a cache memory, comprising:
generating several regular grids of different resolution level terrain patches to represent the terrain data of the massive database;
extracting terrain data from the massive database for several resolution levels, the extracted terrain data forming an extraction pyramid composed of an extraction window for each level of detail, placed in cache memory;
selecting the patches of the extraction pyramid which contribute to the image; and
plotting the rendering on the basis of the selected patches.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the terrain data are extracted for several resolution levels so as to build an extraction pyramid, the extraction pyramid consisting of a sliding extraction window for each resolution level, the sliding extraction window being defined by an identical number of terrain patches which is fixed for all the resolution levels, the patches extending around a position termed the position of the centre of the sliding extraction window, the centre of the sliding extraction window evolving in real time as a function of the evolution of the position of a centre of interest, the centre of interest being determined as a function of the position of the observer with respect to the display device.

### Claim 3 (depends on 1)

The method according to claim 1, wherein a sliding window is placed in cache memory, comprises an active zone intended to be displayed, and a preloading zone which makes it possible to anticipate the transfers of the said data.

### Claim 4 (depends on 2)

The method according to claim 2, wherein the width of a sliding extraction window is defined by an even number of terrain patches.

### Claim 5 (depends on 2)

The method of rendering according to claim 2, wherein an extraction pyramid comprising for each different resolution level a sliding extraction window consisting of a grid of patches, the spacing of displacement of the centre of a sliding extraction window of resolution level L, is aligned with the spacing of a grid of resolution level L+1, L being an integer, resolution level L+1 being less detailed than resolution level L.

### Claim 6 (depends on 5)

The method of rendering according to claim 5, wherein the different resolution grids of the sliding window form a quaternary tree, each level of the tree corresponding to a resolution level.

### Claim 7 (depends on 6)

The method of rendering according to claim 6, wherein the rendering of each patch of the sliding window is determined by traversing the quaternary tree depth-wise from the least resolved level to the most resolved level.

### Claim 8 (depends on 7)

The method of rendering according to claim 7, wherein each patch P of level L in intersection with the field of vision, and situated in the margin of transition of the resolution level L−1, is plotted by mixing the patch P with its children in the quaternary tree.