Method and device for projecting a panoramic image with a variable resolution
Embodiments include a method and apparatus for projecting a panoramic image, the method including steps of generating an image on an image generation surface, and then projecting the generated image on a projection surface to obtain a panoramic projected image, the points of the generated image being projected on the projection surface according to a non uniform distribution determined as a function of at least one parameter of a set comprising the shape of the generated image, the shape of the projection surface, and the position of an observation point of the projected image, in relation to the projection surface.
1. A method for projecting a panoramic image comprising:
generating an image for projection on an image generation surface,
modifying the generated image, prior to projecting the generated image on a projection surface, to obtain a panoramic projected image having an angular resolution, seen from a particular observation point located outside a center of curvature of the projection surface, which is constant on the whole projection surface, the modification of the generated image being a function of at least one parameter of a set comprising the shape of the generated image on the image generation surface, the shape of the projection surface, and the position of the observation point in relation to the projection surface, and
projecting the modified generated image on the projection surface to obtain the panoramic projected image.
2. The method according to claim 1 , wherein the observation point is located on an optical axis according to which the projection is performed.
3. The method according to claim 2 , wherein the points of the generated image projected on the projection surface have a size defined by the following formula:
Dh
(
θ
)
=
k
·
DO
2
+
R
2
-
2
DO
·
R
cos
θ
where Dh(θ) is the size of a projected point or the distance between two adjacent projected points as a function of the field angle θ along a meridian of the projection surface, k is a constant, R is the radius of curvature of the projection surface, and DO is the distance between the center of an external projection lens and the observation point.
4. The method according to claim 1 , wherein the position of the observation point in relation to the projection surface is determined in order to match a central position of an area occupied by several observers, or an average position susceptible of being occupied by one observer.
5. The method according to claim 1 , wherein the image generation surface has a rectangular shape, the generated image having a shape which surface is greater than that of a disc inscribed in the image generation surface.
6. The method according to claim 5 , wherein the generated image has an elliptical shape inscribed in the image generation surface.
7. The method according to claim 1 , wherein the projection surface has a shape different from a hemispherical shape.
8. The method according to claim 1 , wherein the projection surface has several faces linked between them by sharp edges.
9. The method according to claim 8 , wherein the projected image comprises several images, each being projected on a respective face of the projection surface.
10. The method according to claim 1 , comprising digitally preprocessing the image in order to modify the distribution of the pixels of the generated image.
11. The method according to claim 1 , wherein the image is projected using at least one anamorphic optical component.
12. A device for projecting a panoramic image, comprising:
a device for generating an image on a plane image generation surface; and
an optical projection device for projecting the generated image on a projection surface, to obtain a panoramic projected image, the projection device being configured so that an angular resolution of the panoramic image projected on the projection surface, seen from a particular observation point located outside a center of curvature of the projection surface, is constant on the whole projection surface, the optical projection device being configured as a function of at least one parameter of a set comprising the shape of the generated image on the image generation surface, the shape of the projection surface, and the position of the observation point in relation to the projection surface.
13. The device according to claim 12 , wherein the observation point is located on an optical axis according to which the projection is performed.
14. The device according to claim 13 , configured to project the points of the generated image on the projection surface with a size defined by the following formula:
Dh
(
θ
)
=
k
·
DO
2
+
R
2
-
2
DO
·
R
cos
θ
where Dh(θ) is the size of a projected point or the distance between two adjacent projected points as a function of the field angle θ along a meridian of the projection surface, k is a constant, R is the radius of curvature of the projection surface, and DO is the distance between the center of an external projection lens of the optical device and the observation point.
15. The device according to claim 12 , wherein the position of the observation point in relation to the projection surface is determined in order to match a central position of an area occupied by several observers, or an average position susceptible of being occupied by one observer.
16. The device according to claim 12 , wherein the image generation surface has a rectangular shape, the device being configured to generate an image having a shape which surface is greater than that of a disc inscribed in the image generation surface.
17. The device according to claim 16 , wherein the generated image has an elliptical shape inscribed in the image generation surface.
18. The device according to claim 12 , wherein the optical projection device comprises at least one anamorphic optical component.
19. The device according to claim 12 , configured to project the generated image on the projection surface which shape is different from a hemispherical shape.
20. The device according to claim 12 , configured to project the generated image on the projection surface having several faces linked between them by sharp edges.
21. The device according to claim 20 , configured to project several images comprised in the generated image, on a respective face of the projection surface.
22. The device according to claim 12 , configured to apply a digital preprocessing to the image in order to modify the distribution of the pixels of the generated image.