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| comment | | "parent_author":"",<br>"parent_permlink":"science",<br>"author":"ertwro",<br>"permlink":"the-science-of-glittery-shit-dyi-xd",<br>"title":"The Science of Glittery Shit + DYI! XD",<br>"body":"![ (https:\/\/steemitimages.com\/DQmfPCzKzu6SMZPCRXyER6MR3UkDH7FmjphyqB4NwNXXU3E\/image.png)\n[source (https:\/\/i.pinimg.com\/originals\/fd\/b0\/2f\/fdb02f56cd2a959a47d777c8691e8a5d.jpg)\n\n# I'm gonna focus on retroreflective materials and their physics.\n#### You'll also learn how to make a high quality cheap green screen.\n-----------\n\nIndex:\n\n**1. Story**\n**2. Insight**\n**3. Physics**\n**4. Practical shit**\n\n\n> This starts with a story. \nDon't skip. Is cool I promise.\n\n# ***Story:***\nLast year I was trying to get a green screen to do a video for a pharmacology series of lectures on YouTube. As I researched the topic and tried to do the video with chroma I realized how fastidious good chroma key is. Is light intensive (you need to illuminate evenly all the surface),<br> hardware intensive,<br> time intensive (post processing could take hours). So I told myself... Isn't there anything better? Has SCIENCE failed me? \n\nThen it dawned on me. Like some sort of demonic deer in the middle of the night while on the road.\n\n**Of course,<br> Retroreflectivity!**\n![ (https:\/\/steemitimages.com\/DQme4JN8WPqzRRU8hiTtmrVAXcTSefUuYAhg2f1XR39L5Eq\/image.png)\n\n----------------\n\n# ***Insight:***\nIf a material bounces light uniformly then you require less light if the source and the receptor are in the same direction. You also need the minimum scattering of that light possible. \n\nIn some vertebrates like deer and cats,<br> you have *tapetum lucidum* a structure immediately behind the retina that reflects visible light towards the photoreceptors.\n\n![ (https:\/\/steemitimages.com\/DQmNvsWVNtG59V3AgMckGRMSiwrd2MWSSGV8f5AGppXb7in\/image.png)\n[Bovine Tapetum Lucidum,<br> Source (https:\/\/upload.wikimedia.org\/wikipedia\/commons\/c\/c1\/Bovine_Tapetum_Lucidum.jpg?download)\n\nWe humans don't have this structure. Some say is a design mistake. ![ (https:\/\/steemitimages.com\/DQmXMoyD3RcQLCZbG7w9c7uCNnnb2zHuVujrzGnsXc99Ttu\/image.png) the red eye effect is a consequence of light reflecting on our blood vessels and retina. If there's a change in color usually seen in people with foreign bodies like prosthetics or tumors like the leukocoria of \"*retinoblastoma*\"\n![ (https:\/\/steemitimages.com\/DQmaq8bc6YvT6Wwp89VLuCLQX1paVM4KyyUd4zULutYeuJm\/image.png)\n[Child with unilateral Retinoblastoma,<br> source (https:\/\/chect.org.uk\/wp-content\/uploads\/2015\/01\/rsz_1baby_front-1050x688.jpg)\n\n`Even if there are sources of visible light that the eye can't perceive with uniformity you can use the same physical principles to feed a different photoreceptor. A camera !!!!!`\n![ (https:\/\/steemitimages.com\/DQmTNivtw2ueEsGZTjaSu6KfevuHb5jyw3C5uRyNjbbJ5qy\/image.png)\n[source (https:\/\/i.ytimg.com\/vi\/ZeoUyHuu8oo\/maxresdefault.jpg)\n\nYou also could use it to combat paparazzi's\n![ (https:\/\/steemitimages.com\/DQmUs5mfvTN38k46Lg3V8g5zHa8ff77uWDKeT9DDGFHQPkt\/image.png)\n[Source (http:\/\/static.boredpanda.com\/blog\/wp-content\/uploads\/2015\/02\/anti-paparazzi-clothing-chris-holmes-13.jpg)\n\n-----------\n# ***Physics:***\n\n\"In a retroreflector,<br> a magnetic wavefront is reflected in a vector parallel but opposite to the source of the electromagnetic wave.\" Wiki\n\n![ (https:\/\/steemitimages.com\/DQmUaTXfqKzJV2vv34afnpEGKL1iLdvgnkYVi517SxcPB5i\/image.png)https:\/\/upload.wikimedia.org\/wikipedia\/commons\/c\/c7\/Lens_and_wavefronts.gif\n[Wavefronts,<br> source (https:\/\/i.ytimg.com\/vi\/ZeoUyHuu8oo\/maxresdefault.jpg)\n\nThere are many methods to create retroreflectos. I'll mention two: Corner and spherical.\n\n![ (https:\/\/steemitimages.com\/DQmQ8DbV8CTYfovG7DxakiiHhiSsfHJ8yQn7PhYFMAvQQiQ\/image.png)\n[source (https:\/\/en.wikipedia.org\/wiki\/Retroreflector#\/media\/File:Comparison_of_retroreflectors.svg)\n\nPlanar mirrors create this effect at an angle of incidence zero,<br> this means when the light source and the photoreceptor are exactly perpendicular. Like in the case of the *lady toilet pic at the beginning,<br> remember*.![ (https:\/\/steemitimages.com\/DQmUiemKrQo4AYfZ8wYVYbRk4V6Ws3Qd7FZBqyAnT8VbJxs\/image.png) \nA retroreflector achieves this at angles greater than zero,<br> in three planes.\n\n![ (https:\/\/steemitimages.com\/DQmc2ZLHoTAcfqtYXHpZ1sWePnSuyGAxKELKQSWVc4JHsFD\/image.png)\n[source (https:\/\/en.wikipedia.org\/wiki\/Retroreflector#\/media\/File:Observation_angle_retroreflector.PNG)\n\nThe material used by the retroreflective fabric used by cyclists for road safety is of the spherical type. Small spheres mixed with the paint or the material itself.\n\n![ (https:\/\/steemitimages.com\/DQmWxn5VMiK9uHqRhdnqfx2mPRMVTwp5FNpVUcEyhRK5sJD\/image.png)\n[Source (http:\/\/www.australiansafetyreflectors.com.au\/media\/pics\/site\/imagecache\/9\/6\/96CDC4F9677521F9A13DD78D5391A0C2.jpg)\n\nIn order to get this effect with low divergence,<br> the glass beads must have a refractive index of 1 plus the refractive index of the medium \"in\". (Ni is approximately 1 for air) \n#### ni + 1 \u2245 2\nNormal glass has 1.5 and high index materials like [Barium titanate (https:\/\/en.wikipedia.org\/wiki\/Barium_titanate) Have 1.9!\n\nNow,<br> if the electromagnetic wave has a narrow spectrum,<br> like a laser or an LED light,<br> then you can have a selective perception of the light reflected at the photoreceptor with uniformity. \n\n![ (https:\/\/steemitimages.com\/DQmPP8yAJoubAqUDdj1QrXnVBu9CLvTSjfSF1CSourwJGQ4\/image.png)\n[Source (https:\/\/sc01.alicdn.com\/kf\/HTB1waWvIVXXXXXlXpXXq6xXFXXXP\/200075416\/HTB1waWvIVXXXXXlXpXXq6xXFXXXP.jpg)\n\n![ (https:\/\/steemitimages.com\/DQmeS5nEjGoC4SHTBfNUTh7m7TA6t9dv21BCoHvkU8STdRZ\/image.png)\n[Source (http:\/\/4.imimg.com\/data4\/WR\/MP\/MY-4261710\/road-paint-500x500.jpg)\n-------------- \n\n# ***Practical shit:***\n\n\nGet your High quality,<br> portable. Super pragmatic green screen works even with bad lighting (chroma)\n\n1. Get some retroreflective fabric (Check the Reflective Coefficient is at least >380cd\/lux.m2) $3 the square meter [link (https:\/\/www.alibaba.com\/product-detail\/en471-photographic-waterproof-retro-reflective-fabric_60643508834.html?spm=a2700.7724857.main07.12.2bd13975laM17g&s=p)\n2. Get a green led light strip ( ideally 95 CRI but lower can work if is non-dimmable)\n3. Get any camera.\n\n***VIDEO DOWNHERE***\nhttps:\/\/www.youtube.com\/watch?v=VIYvgBDx0Jk\n\n-----\n\n**ALTERNATIVE**\n\nYou could go super ghetto with \"glass beads paint\" ,<br> \"cardboard\",<br> your cellphone and a led strip.\n\n***VIDEO DOWNHERE***\nhttps:\/\/www.youtube.com\/watch?v=-jUgjq02H9Q\n\n\n\n\n\n# Finally,<br> as renowned scientist Rick Sanchez recommends,<br> I must ask:\n\n> \u266a\u266a ... Hey,<br> did you ever wanna hold a terry-fold? \n\n> I got one right here.\n\n> Grab a terry flap. Squeeze it! ...\u266a\u266a\n\n------------------\n\n***References:***\n\nhttps:\/\/en.wikipedia.org\/wiki\/Tapetum_lucidum\n\nhttps:\/\/en.wikipedia.org\/wiki\/Retinoblastoma\n\nhttps:\/\/en.wikipedia.org\/wiki\/Retroreflector\n\nOptical Engineering,<br> Vol. 21,<br> pp. 281\u2013283 (March\/April 1982),<br> \"Experiments with Retrodirective Arrays,<br>\" by Stephen F. Jacobs.\n\nhttp:\/\/science.howstuffworks.com\/invisibility-cloak.htm",<br>"json_metadata":" \"tags\":[\"science\",<br>\"physics\",<br>\"dyi\",<br>\"video\",<br>\"greenscreen\" ,<br>\"image\":[\"https:\/\/steemitimages.com\/DQmfPCzKzu6SMZPCRXyER6MR3UkDH7FmjphyqB4NwNXXU3E\/image.png\",<br>\"https:\/\/steemitimages.com\/DQme4JN8WPqzRRU8hiTtmrVAXcTSefUuYAhg2f1XR39L5Eq\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmNvsWVNtG59V3AgMckGRMSiwrd2MWSSGV8f5AGppXb7in\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmXMoyD3RcQLCZbG7w9c7uCNnnb2zHuVujrzGnsXc99Ttu\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmaq8bc6YvT6Wwp89VLuCLQX1paVM4KyyUd4zULutYeuJm\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmTNivtw2ueEsGZTjaSu6KfevuHb5jyw3C5uRyNjbbJ5qy\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmUs5mfvTN38k46Lg3V8g5zHa8ff77uWDKeT9DDGFHQPkt\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmUaTXfqKzJV2vv34afnpEGKL1iLdvgnkYVi517SxcPB5i\/image.png\",<br>\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/c\/c7\/Lens_and_wavefronts.gif\",<br>\"https:\/\/steemitimages.com\/DQmQ8DbV8CTYfovG7DxakiiHhiSsfHJ8yQn7PhYFMAvQQiQ\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmUiemKrQo4AYfZ8wYVYbRk4V6Ws3Qd7FZBqyAnT8VbJxs\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmc2ZLHoTAcfqtYXHpZ1sWePnSuyGAxKELKQSWVc4JHsFD\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmWxn5VMiK9uHqRhdnqfx2mPRMVTwp5FNpVUcEyhRK5sJD\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmPP8yAJoubAqUDdj1QrXnVBu9CLvTSjfSF1CSourwJGQ4\/image.png\",<br>\"https:\/\/steemitimages.com\/DQmeS5nEjGoC4SHTBfNUTh7m7TA6t9dv21BCoHvkU8STdRZ\/image.png\",<br>\"https:\/\/img.youtube.com\/vi\/VIYvgBDx0Jk\/0.jpg\",<br>\"https:\/\/img.youtube.com\/vi\/-jUgjq02H9Q\/0.jpg\" ,<br>\"links\":[\"https:\/\/i.pinimg.com\/originals\/fd\/b0\/2f\/fdb02f56cd2a959a47d777c8691e8a5d.jpg\",<br>\"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/c\/c1\/Bovine_Tapetum_Lucidum.jpg?download\",<br>\"https:\/\/chect.org.uk\/wp-content\/uploads\/2015\/01\/rsz_1baby_front-1050x688.jpg\",<br>\"https:\/\/i.ytimg.com\/vi\/ZeoUyHuu8oo\/maxresdefault.jpg\",<br>\"http:\/\/static.boredpanda.com\/blog\/wp-content\/uploads\/2015\/02\/anti-paparazzi-clothing-chris-holmes-13.jpg\",<br>\"https:\/\/en.wikipedia.org\/wiki\/Retroreflector#\/media\/File:Comparison_of_retroreflectors.svg\",<br>\"https:\/\/en.wikipedia.org\/wiki\/Retroreflector#\/media\/File:Observation_angle_retroreflector.PNG\",<br>\"http:\/\/www.australiansafetyreflectors.com.au\/media\/pics\/site\/imagecache\/9\/6\/96CDC4F9677521F9A13DD78D5391A0C2.jpg\",<br>\"https:\/\/en.wikipedia.org\/wiki\/Barium_titanate\",<br>\"https:\/\/sc01.alicdn.com\/kf\/HTB1waWvIVXXXXXlXpXXq6xXFXXXP\/200075416\/HTB1waWvIVXXXXXlXpXXq6xXFXXXP.jpg\",<br>\"http:\/\/4.imimg.com\/data4\/WR\/MP\/MY-4261710\/road-paint-500x500.jpg\",<br>\"https:\/\/www.alibaba.com\/product-detail\/en471-photographic-waterproof-retro-reflective-fabric_60643508834.html?spm=a2700.7724857.main07.12.2bd13975laM17g&s=p\",<br>\"https:\/\/www.youtube.com\/watch?v=VIYvgBDx0Jk\",<br>\"https:\/\/www.youtube.com\/watch?v=-jUgjq02H9Q\",<br>\"https:\/\/en.wikipedia.org\/wiki\/Tapetum_lucidum\",<br>\"https:\/\/en.wikipedia.org\/wiki\/Retinoblastoma\",<br>\"https:\/\/en.wikipedia.org\/wiki\/Retroreflector\",<br>\"http:\/\/science.howstuffworks.com\/invisibility-cloak.htm\" ,<br>\"app\":\"steemit\/0.1\",<br>\"format\":\"markdown\" " |
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