中国科学技术大学：《计算机视觉》课程教学资源（PPT课件讲稿）第九章 单幅图像深度重建 Depthmap Reconstruction Based on Monocular cues（1/2）Shape From Shading

第九章单幅图像深度重建 Depthmap Reconstruction Based on monocular cues

第九章 单幅图像深度重建 Depthmap Reconstruction Based on Monocular cues

章节安排 基于单眼线索的深度重建 >Shape From Shading >Shape From Vanishing Point Shape From Defocus Shape From Texture 极秋私

章节安排 ▪ 基于单眼线索的深度重建 ➢ Shape From Shading ➢ Shape From Vanishing Point ➢ Shape From Defocus ➢ Shape From Texture

Shape From Shading

Shape From Shading

What is Shading? Well...not shadow... 西 We can't reconstruct shape from one shadow

What is Shading? ▪ Well… not shadow… ▪ We can’t reconstruct shape from one shadow…

What is Shading? Variable levels of darkness Gives a cue for the actual 3D shape There is a relation between intensity and shape 陶

What is Shading? ▪ Variable levels of darkness ▪ Gives a cue for the actual 3D shape ▪ There is a relation between intensity and shape

Shading Examples These circles differ only in grayscale intensity none flat gouraud phong Intensities give a strong“feeling”of scene 得 structure

Shading Examples ▪ These circles differ only in grayscale intensity ▪ Intensities give a strong “feeling” of scene structure

What determines scene radiance? ■ The amount of light that falls on the surface The fraction of light that is reflected (albedo) Geometry of light reflection >Shape of surface 0iPi >Viewpoint (Oe,Pe

What determines scene radiance? ▪ n

Albedo p -A property of the surface >Usually normalized1≥p≥0 Can be modeled as a single scalar for the entire surface or dependent on location Usually assumed to be a known scalar >Is this a ball with uniform albedo or is this a 2D circle with varying albedo?

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Surface Normal Convenient notation for surface orientation A smooth surface has a tangent plane at every point We can model the surface using the normal at every point 蘭

Surface Normal Convenient notation for surface orientation  A smooth surface has a tangent plane at every point  We can model the surface using the normal at every point

The Shape From Shading Problem Given a grayscale image >And albedo >And light source direction Reconstruct scene geometry Can be modeled by surface normals

The Shape From Shading Problem ▪ Given a grayscale image ➢And albedo ➢And light source direction ▪ Reconstruct scene geometry ➢Can be modeled by surface normals