Computer Vision Foundations · free preview
Imaging with Lenses
The three ray rules that locate image points, the center ray that makes a lens behave like a pinhole, and the ratio that sets image size.
1. Three rays that locate any image
Three rays that locate any image
2. The center ray is a pinhole
The center ray is a pinhole
3. Image size follows the distances
Image size follows the distances
4. Framing and the field of view
Framing and the field of view
5. Locating an image point
A world point sits off the optical axis above the lens. Which ray construction gives its image position in the plane one has already found with the lensmaker relation?
6. The portrait effect
Two portraits of the same face are taken with the head filling the frame. The first uses a short lens from close range, the second a long lens from far away. Why does the close shot enlarge the nose relative to the ears?
7. Image size from the distance ratio
An object of height centimeters stands centimeters in front of a lens whose conjugate image distance is centimeters. Using image height equal to object height times , compute the image height in centimeters and write the number.
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