Images and apparatus for carrying out the method

• US 6,078,333 A
• Filed: 02/20/1998
• Issued: 06/20/2000
• Est. Priority Date: 02/21/1997
• Status: Expired due to Term

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Gmd--Forschungszentrum Informationstechnik GmbH
• Inventors: Budianto, Suwanto, Wittig, Oliver
• Primary Examiner(s): Powell, Mark R.
• Assistant Examiner(s): GOOD JOHNSON, MOTILEWA
• Application Number:
  US09/026,694
• Time in Patent Office: 851 Days
• Field of Search: 345/502, 345/505, 345/506, 345/425, 345/430, 345/426
• US Class Current: 345/426
• CPC Class Codes: G06T 15/55 Radiosity

Abstract

In an image-processing method and apparatus for displaying computer-modeled objects that are present in the form of a grid model and are simulated by a plurality of adjacent polygon surfaces, the individual polygon surfaces are divided into pixels and the image impression of each pixel is calculated, on the one hand, corresponding to Phong'"'"'s illumination model and, on the other hand, by suitable addressing of storage matrices (8, 9) that represent the image impression of the environment, so both a natural-looking shading and the consideration of reflections of the environment in the objects are possible; the environment reflections can be modulated from perfect mirroring of the environment to a complete lack of mirroring.

Claims

1. An imaging method for displaying computer-modeled objects that are present in the form of a grid model and are simulated by a plurality of adjacent polygon surfaces, in which

a first pipeline (3, 4) calculates a plurality of first coordinate sets from a predetermined, first parameter set that respectively represents the spatial position of one of the polygon surfaces, the coordinate sets respectively representing the spatial position of a pixel of the respective polygon surface,

a second pipeline (5, 6) uses the first parameter set representing the spatial position of the polygon surface to calculate a second coordinate set for each pixel of the polygon surface, which set represents the spatial position of the local surface normal (N),

a third pipeline (7) uses the first coordinate sets representing the spatial position of the individual pixels, and the second coordinate sets representing the spatial position of the local surface normal (N), as well as a predetermined, second parameter set that represents the spatial position and the optical properties of at least one first light source, and a predetermined, third parameter set that represents the position of a virtual viewer to calculate a first image-information value corresponding to a local illumination model, which value represents an image impression of the respective pixel from the perspective of the viewer,

a fourth pipeline (14) uses the first coordinate set representing the spatial position of the respective pixel to calculate a two-dimensional screen-coordinate set for each pixel for display on a screen (13), which set determines the position of the pixel on the screen (13),

characterized in that

a first calculation unit (10, 11) calculates a first addressing value for the individual pixels using the second coordinate sets representing the spatial position of the local surface normal (N) and/or the third parameter set representing the position of the virtual viewer, and the first coordinate set representing the spatial position of the pixel,

the first addressing value is used to address a storage location of a first storage matrix (8, 9), and a second image-information value representing the image impression of the environment from a certain perspective is read out of the addressed storage location,

and a third image-information value is calculated from the first and second image-information values for actuating the screen (13) in order to take into consideration both the local illumination model and reflections of the environment by means of a second calculation unit (12).

2. The imaging method according to claim 1, characterized in that an eye vector (E) is calculated from the third parameter set representing the position of the viewer and the first coordinate set representing the spatial position of the pixel, which vector lies in the connecting line between the viewer and the pixel,

the eye vector (M) that is reflected at the pixel in an ideal mirror reflection is calculated from the eye vector (E) and the second coordinate set representing the spatial position of the local surface normal (N),

and that the first addressing value is calculated from the reflected eye vector (M), and represents the point of intersection of the reflected eye vector (M) and a cubic envelope surface that encompasses the pixel or the polygon surface, wherein the first storage matrix (8) represents the image impression of the environment that is to be considered within the scope of mirror reflection.

3. The imaging method according to claim 1, characterized in that

a third calculation unit (11) uses the second coordinate set representing the spatial position of the local surface normal (N) to calculate a second addressing value, which represents the point of intersection of the local surface normal (N) and a cubic envelope surface encompassing the pixel or the polygon surface,

the second addressing value is used to address a storage location of a second storage matrix (9), and a fourth image-information value is read out of the addressed storage location, which value represents an image impression of the environment that is to be considered within the scope of diffuse reflection,

the second calculation unit (12) calculates the third image-information value serving to actuate the screen (13) from the first image-information value that has been determined corresponding to the local illumination model, and the second image-information value representing specular environment reflections, as well as from the fourth image-information value representing diffuse environment reflections.

4. The imaging method according to claim 1, characterized in that the first addressing value and/or the second addressing value is or are calculated as a function of the first parameter set representing the spatial position of the polygon surface, or the first coordinate set representing the spatial position of the pixel, for position-dependent addressing of different storage areas of the first storage matrix (8) and/or the second storage matrix (9), each area defining different environments.

5. The imaging method according to claim 1, characterized in that a selection value is calculated as a function of the first parameter set representing the spatial position of the polygon surface, or the first coordinate set representing the spatial position of the pixel, for position-dependent display of different environments, and the first storage matrix (8) and/or the second storage matrix (9) is or are selected, as a function of the selection value, from a plurality of storage matrices that define different environment impressions.

6. The imaging method according to claim 1, characterized in that the first storage matrix (8) and/or the second storage matrix (9) define(s) a partial region of the environment to be represented, wherein a storage location of the first storage matrix (8) and/or a storage location of the second storage matrix (9) is or are unambiguously associated with each spatial-angle region of the environment to be represented, and the first and/or the second addressing value is or are calculated under the assumption that the predetermined partial region repeats on the cubic envelope surface.

7. The imaging method according to claim 6, characterized in that the second image-information values stored in the first storage matrix (8) and/or the fourth image-information values of a predetermined image pattern that are stored in the second storage matrix (9) are read in and, to attain a natural image impression, are subsequently changed by an image-processing unit such that no jumps in intensity or color occur between adjacent partial regions along the impact edge, and/or the change in intensity or color values is constant over the impact edge.

8. The imaging method according to claim 1, characterized in that

a third addressing value, which represents the position of the pixel within the polygon surface, is calculated from the first coordinate set representing the spatial position of the pixel and the first parameter set representing the spatial position of the polygon surface,

the third addressing value is used to address a storage location of a third storage matrix, and a fifth image-information value that defines the texture of the polygon surface is read out of the addressed storage location, and the second calculation unit (12) calculates the third image-information value serving to actuate the screen (13) as a function of the fifth image-information value.

9. An apparatus for displaying computer-modeled objects that are present in the form of a grid model and are simulated by a plurality of adjacent polygon surfaces, particularly for executing the imaging method according to one of the foregoing claims, having

a first pipeline (3, 4) for using a predetermined, first parameter set that represents the polygon surface to calculate a plurality of first coordinate sets that represent the spatial position of a pixel of the respective polygon surface,

a second pipeline (5, 6) for calculating the second coordinate sets representing the spatial position of the local surface normals (N) in the individual pixels as a function of the first parameter set,

a third pipeline (7) for calculating a first image-information value that respectively represents a pixel, corresponding to a local illumination model, as a function of the first coordinate set representing the spatial position of the pixel and the second coordinate set representing the spatial position of the local surface normal (N), and a predetermined, second parameter set that determines the spatial positon and the optical properties of at least one light source, as well as a predetermined, third parameter set that determines the position of a virtual viewer,

and a fourth pipeline (14) for calculating a two-dimensional screen-coordinate set for each pixel from the first coordinate set representing the spatial position of the pixel, characterized in that

a first storage matrix (8, 9) is provided for representing reflections of the environment in the surface of the object, wherein each storage location of the first storage matrix (8, 9) includes a second image-information value that represents the image impression of the environment from a certain perspective,

a first calculation unit (10, 11), which is connected on the output side to the first storage matrix (8, 9) for addressing a storage location, is provided for calculating a first addressing value as a function of the second coordinate sets representing the spatial position of the local surface normal (N), and/or the third parameter set representing the position of the virtual viewer, and the first coordinate set representing the spatial position of the pixel,

and a second calculation unit (12), which is connected on the input side to the third pipeline (7) for receiving the first image-information value corresponding to the local illumination model, and to the first storage matrix (8, 9) for receiving the second image-information value representing the reflections of the environment, is provided for calculating a third image-information value that takes into account both the local illumination model and reflections of the environment.

10. The apparatus according to claim 9, characterized in that

a second storage matrix (9) is provided for representing diffuse environment reflections, wherein each storage location of the second storage matrix (9) contains a fourth image-information value, which contains the image impression of the environment that is to be considered in diffuse reflection,

a third calculation unit (11) is provided for calculating a second addressing value, the unit being connected on the input side to the second pipeline (6) for receiving the second coordinate set representing the spatial position of the local surface normal (N), and on the output side to the second storage matrix (9) for addressing with the second addressing value,

and the second calculation unit (12) is connected on the input side to the second storage matrix (9) for using the first image-information value determined corresponding to the local illumination model, and the second image-information value representing specular environment reflections, and the fourth image-information value representing diffuse environment reflections, to calculate the third image-information value serving to actuate the screen (13).

11. The apparatus according to claim 9, characterized in that a fourth calculation unit (10, 11) is provided for using the first parameter set representing the spatial position of the polygon surface, or the first coordinate set representing the spatial position of the pixel, to calculate a selection value that is dependent on the position of the polygon surface or pixel,

the fourth calculation unit (10, 11) is connected to the first and/or the second storage matrix (8, 9) for position-dependent selection of a storage area, or to a selection unit (10, 11) for position-dependent selection of the first and/or second storage matrix (8, 9) from a plurality of storage matrices.

12. The apparatus according to claim 9, characterized in that the first storage matrix and/or the second storage matrix contains an all-around recording from the perspective of the respective pixel or polygon surface, and a spatial-angle region of the environment to be represented is unambiguously associated with each storage location of the first storage matrix and/or each storage location of the second storage matrix.

13. The apparatus according to claim 9, characterized in that the first storage matrix and/or the second storage matrix define(s) a partial region of the environment to be represented, wherein a storage location of the first storage matrix and/or the second storage matrix is unambiguously associated with each spatial-angle region of the environment to be represented,

a first addressing unit, which is connected on the input side to the first and/or the second calculation unit(s) for receiving the first or second addressing value that determines the spatial-angle region of the environment to be represented, and on the output side to the first and/or second storage matrix, is provided for addressing the first storage matrix and/or the second storage matrix.

14. The apparatus according to claim 13, characterized in that the first storage matrix and/or the second storage matrix is or are connected to an image-processing unit, which changes the second image-information values stored in the first storage matrix, and/or the fourth image-information values stored in the second storage matrix, such that, to attain a natural image impression, no jumps in intensity or color occur between adjacent partial regions along the impact edge, and/or the change in intensity or color values is constant over the impact edge.

15. The apparatus according to claim 9, characterized in that a third storage matrix is provided for simulating a texture of the respective polygon surface, wherein a storage location of the third storage matrix is associated with each pixel of the polygon surface, and the individual storage locations of the third storage matrix respectively contain a fifth image-information value that defines the texture,

a second addressing unit is provided for calculating a third addressing value that represents the spatial position of the respective pixel within the respective polygon surface, and for addressing the third storage matrix with the third addressing value,

and the second calculation unit (12) is connected on the input side to the third storage matrix for calculating the third image-information value serving to actuate the screen (13) as a function of the fifth image-information value that defines the texture.