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Lecture 11: Radiometry & Photometry (52)
ShaamerKumar

How would we reproduce/ think about the retro-reflective case? It is easy to visualise the first one, but the rest are a bit harder

madssnake

Would we need to manually assign reflection function types to all our different objects/materials we are rendering? Or do different textures already have this information?

yzliu567

A corner reflector is a good example. I think this is a simple way to obtain retro-reflective in real world. See this.

JerryIshihara

Nowadays, machine learning can be used to estimate the light reflection function of various materials based on their physical properties. Based on their reflectance properties, it can also be used to detect outliers in estimation. This paper is a good example: https://link.springer.com/article/10.1007/s00371-019-01666-x.

adham-elarabawy

A cool application of retro reflective materials is in computer vision targets. If a retroreflective material is placed on a target, and a light is placed near a camera that is pointing towards the target, then the camera will see the retroreflective target as extremely bright (in the color of the light being shined in that direction), whereas any other observer viewing the target from other directions would see the retroreflective material as essentially diffuse!

Unicorn53547

In real application, how woul we decide which reflection to use and how to implment those based on different materials? Do we just store some information for some particular material and use the data? It seemed challenging to adjust based on every different objects.

alvin-xu-5745

A cool historic application of retroreflection was to measure the distance between the Earth and the moon. This was done by shooting a laser at the moon, which was reflected back to the exact place on Earth from the retroreflectors placed on the moon during the Apollo missions. Taking the travel time and the speed of light, the distance could be calculated. This was particularly used over things like wave travel times because lasers had less spread and thus could be measured more precisely.

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