COLOR

LIGHTING

  • Debayer – A free command line tool to convert camera raw images into scene-linear exr

    https://github.com/jedypod/debayer

     

     

    The only required dependency is oiiotool. However other “debayer engines” are also supported.

    • OpenImageIO – oiiotool is used for converting debayered tif images to exr.
    • Debayer Engines
      • RawTherapee – Powerful raw development software used to decode raw images. High quality, good selection of debayer algorithms, and more advanced raw processing like chromatic aberration removal.
      • LibRaw – dcraw_emu commandline utility included with LibRaw. Optional alternative for debayer. Simple, fast and effective.
      • Darktable – Uses darktable-cli plus an xmp config to process.
      • vkdt – uses vkdt-cli to debayer. Pretty experimental still. Uses Vulkan for image processing. Stupidly fast. Pretty limited.
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    Read more: Debayer – A free command line tool to convert camera raw images into scene-linear exr
  • Photography basics: How Exposure Stops (Aperture, Shutter Speed, and ISO) Affect Your Photos – cheat sheet cards

     

    Also see:

    https://www.pixelsham.com/2018/11/22/exposure-value-measurements/

     

    https://www.pixelsham.com/2016/03/03/f-stop-vs-t-stop/

     

     

    An exposure stop is a unit measurement of Exposure as such it provides a universal linear scale to measure the increase and decrease in light, exposed to the image sensor, due to changes in shutter speed, iso and f-stop.

     

    +-1 stop is a doubling or halving of the amount of light let in when taking a photo

     

    1 EV (exposure value) is just another way to say one stop of exposure change.

     

    https://www.photographymad.com/pages/view/what-is-a-stop-of-exposure-in-photography

     

    Same applies to shutter speed, iso and aperture.
    Doubling or halving your shutter speed produces an increase or decrease of 1 stop of exposure.
    Doubling or halving your iso speed produces an increase or decrease of 1 stop of exposure.

     

    Because of the way f-stop numbers are calculated (ratio of focal length/lens diameter, where focal length is the distance between the lens and the sensor), an f-stop doesn’t relate to a doubling or halving of the value, but to the doubling/halving of the area coverage of a lens in relation to its focal length. And as such, to a multiplying or dividing by 1.41 (the square root of 2). For example, going from f/2.8 to f/4 is a decrease of 1 stop because 4 = 2.8 * 1.41. Changing from f/16 to f/11 is an increase of 1 stop because 11 = 16 / 1.41.

     

     

    https://www.quora.com/Photography-How-a-higher-f-Stop-larger-aperture-leads-to-shallow-Depth-Of-Field

    A wider aperture means that light proceeding from the foreground, subject, and background is entering at more oblique angles than the light entering less obliquely.

    Consider that absolutely everything is bathed in light, therefore light bouncing off of anything is effectively omnidirectional. Your camera happens to be picking up a tiny portion of the light that’s bouncing off into infinity.

    Now consider that the wider your iris/aperture, the more of that omnidirectional light you’re picking up:

     When you have a very narrow iris you are eliminating a lot of oblique light. Whatever light enters, from whatever distance, enters moderately parallel as a whole. When you have a wide aperture, much more light is entering at a multitude of angles. Your lens can only focus the light from one depth – the foreground/background appear blurred because it cannot be focused on.

    https://frankwhitephotography.com/index.php?id=28:what-is-a-stop-in-photography

     

     

     

    The great thing about stops is that they give us a way to directly compare shutter speed, aperture diameter, and ISO speed. This means that we can easily swap these three components about while keeping the overall exposure the same.

     

    http://lifehacker.com/how-aperture-shutter-speed-and-iso-affect-pictures-sh-1699204484

     

     

    https://www.techradar.com/how-to/the-exposure-triangle

     

     

    https://www.videoschoolonline.com/what-is-an-exposure-stop

     

    Note. All three of these measurements (aperture, shutter, iso) have full stops, half stops and third stops, but if you look at the numbers they aren’t always consistent. For example, a one third stop between ISO100 and ISO 200 would be ISO133, yet most cameras are marked at ISO125.

    Third-stops are especially important as they’re the increment that most cameras use for their settings. These are just imaginary divisions in each stop.
    From a practical standpoint manufacturers only standardize the full stops, meaning that while they try and stay somewhat consistent there is some rounding up going on between the smaller numbers.

     

    http://www.digitalcameraworld.com/2015/04/15/the-exposure-triangle-aperture-shutter-speed-and-iso-explained/

     

     

     

     

     

     

    Note that ND Filters directly modify the exposure triangle.

     

     

     

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    Read more: Photography basics: How Exposure Stops (Aperture, Shutter Speed, and ISO) Affect Your Photos – cheat sheet cards
  • About green screens

    hackaday.com/2015/02/07/how-green-screen-worked-before-computers/

     

    www.newtek.com/blog/tips/best-green-screen-materials/

     

    www.chromawall.com/blog//chroma-key-green

     

     

    Chroma Key Green, the color of green screens is also known as Chroma Green and is valued at approximately 354C in the Pantone color matching system (PMS).

     

    Chroma Green can be broken down in many different ways. Here is green screen green as other values useful for both physical and digital production:

     

    Green Screen as RGB Color Value: 0, 177, 64
    Green Screen as CMYK Color Value: 81, 0, 92, 0
    Green Screen as Hex Color Value: #00b140
    Green Screen as Websafe Color Value: #009933

     

    Chroma Key Green is reasonably close to an 18% gray reflectance.

     

    Illuminate your green screen with an uniform source with less than 2/3 EV variation.
    The level of brightness at any given f-stop should be equivalent to a 90% white card under the same lighting.

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    Read more: About green screens
  • Open Source Nvidia Omniverse

    blogs.nvidia.com/blog/2019/03/18/omniverse-collaboration-platform/

     

    developer.nvidia.com/nvidia-omniverse

     

    An open, Interactive 3D Design Collaboration Platform for Multi-Tool Workflows to simplify studio workflows for real-time graphics.

     

    It supports Pixar’s Universal Scene Description technology for exchanging information about modeling, shading, animation, lighting, visual effects and rendering across multiple applications.

     

    It also supports NVIDIA’s Material Definition Language, which allows artists to exchange information about surface materials across multiple tools.

     

    With Omniverse, artists can see live updates made by other artists working in different applications. They can also see changes reflected in multiple tools at the same time.

     

    For example an artist using Maya with a portal to Omniverse can collaborate with another artist using UE4 and both will see live updates of each others’ changes in their application.

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  • LUX vs LUMEN vs NITS vs CANDELA – What is the difference

    More details here: Lumens vs Candelas (candle) vs Lux vs FootCandle vs Watts vs Irradiance vs Illuminance

     

     

     

     

    https://www.inhouseav.com.au/blog/beginners-guide-nits-lumens-brightness/

     

     

    Candela

     

    Candela is the basic unit of measure of the entire volume of light intensity from any point in a single direction from a light source. Note the detail: it measures the total volume of light within a certain beam angle and direction.
    While the luminance of starlight is around 0.001 cd/m2, that of a sunlit scene is around 100,000 cd/m2, which is a hundred millions times higher. The luminance of the sun itself is approximately 1,000,000,000 cd/m2.

     

    NIT

     

    https://en.wikipedia.org/wiki/Candela_per_square_metre

     

    The candela per square metre (symbol: cd/m2) is the unit of luminance in the International System of Units (SI). The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area. The nit (symbol: nt) is a non-SI name also used for this unit (1 nt = 1 cd/m2).[1] The term nit is believed to come from the Latin word nitēre, “to shine”. As a measure of light emitted per unit area, this unit is frequently used to specify the brightness of a display device.

    NIT and cd/m2 (candela power) represent the same thing and can be used interchangeably. One nit is equivalent to one candela per square meter, where the candela is the amount of light which has been emitted by a common tallow candle, but NIT is not part of the International System of Units (abbreviated SI, from Systeme International, in French).

    It’s easiest to think of a TV as emitting light directly, in much the same way as the Sun does. Nits are simply the measurement of the level of light (luminance) in a given area which the emitting source sends to your eyes or a camera sensor.

    The Nit can be considered a unit of visible-light intensity which is often used to specify the brightness level of an LCD.

    1 Nit is approximately equal to 3.426 Lumens. To work out a comparable number of Nits to Lumens, you need to multiply the number of Nits by 3.426. If you know the number of Lumens, and wish to know the Nits, simply divide the number of Lumens by 3.426.

    Most consumer desktop LCDs have Nits of 200 to 300, the average TV most likely has an output capability of between 100 and 200 Nits, and an HDR TV ranges from 400 to 1,500 Nits.
    Virtual Production sets currently sport around 6000 NIT ceiling and 1000 NIT wall panels.

     

    The ambient brightness of a sunny day with clear blue skies is between 7000-10,000 nits (between 3000-7000 nits for overcast skies and indirect sunlight).
    A bright sunny day can have specular highlights that reach over 100,000 nits. Direct sunlight is around 1,600,000,000 nits.
    10,000 nits is also the typical brightness of a fluorescent tube – bright, but not painful to look at.

     

     

    https://www.displaydaily.com/article/display-daily/dolby-vision-vs-hdr10-clarified

    Tests showed that a “black level” of 0.005 nits (cd/m²) satisfied the vast majority of viewers. While 0.005 nits is very close to true black, Griffis says Dolby can go down to a black of 0.0001 nits, even though there is no need or ability for displays to get that dark today.
    How bright is white? Dolby says the range of 0.005 nits – 10,000 nits satisfied 84% of the viewers in their viewing tests.
    The brightest consumer HDR displays today are about 1,500 nits. Professional displays where HDR content is color-graded can achieve up to 4,000 nits peak brightness.

    High brightness that would be in danger of damaging the eye would be in the neighborhood of 250,000 nits.

     

    Lumens

     

    Lumen is a measure of how much light is emitted (luminance, luminous flux) by an object. It indicates the total potential amount of light from a light source that is visible to the human eye.
    Lumen is commonly used in the context of light bulbs or video-projectors as a metric for their brightness power.

    Lumen is used to describe light output, and about video projectors, it is commonly referred to as ANSI Lumens. Simply put, lumens is how to find out how bright a LED display is. The higher the lumens, the brighter to display!

    Technically speaking, a Lumen is the SI unit of luminous flux, which is equal to the amount of light which is emitted per second in a unit solid angle of one steradian from a uniform source of one-candela intensity radiating in all directions.

     

    LUX

     

    Lux (lx) or often Illuminance, is a photometric unit along a given area, which takes in account the sensitivity of human eye to different wavelenghts. It is the measure of light at a specific distance within a specific area at that distance. Often used to measure the incidental sun’s intensity.

     

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    Read more: LUX vs LUMEN vs NITS vs CANDELA – What is the difference
  • Ethan Roffler interviews CG Supervisor Daniele Tosti

    Ethan Roffler
    I recently had the honor of interviewing this VFX genius and gained great insight into what it takes to work in the entertainment industry. Keep in mind, these questions are coming from an artist’s perspective but can be applied to any creative individual looking for some wisdom from a professional. So grab a drink, sit back, and enjoy this fun and insightful conversation.



    Ethan

    To start, I just wanted to say thank you so much for taking the time for this interview!

    Daniele
    My pleasure.
    When I started my career I struggled to find help. Even people in the industry at the time were not that helpful. Because of that, I decided very early on that I was going to do exactly the opposite. I spend most of my weekends talking or helping students. ;)

    Ethan
    That’s awesome! I have also come across the same struggle! Just a heads up, this will probably be the most informal interview you’ll ever have haha! Okay, so let’s start with a small introduction!

    Daniele
    Short introduction: I worked very hard and got lucky enough to work on great shows with great people. ;) Slightly longer version: I started working for a TV channel, very early, while I was learning about CG. Slowly made my way across the world, working along very great people and amazing shows. I learned that to be successful in this business, you have to really love what you do as much as respecting the people around you. What you do will improve to the final product; the way you work with people will make a difference in your life.

    Ethan
    How long have you been an artist?

    Daniele
    Loaded question. I believe I am still trying and craving to be one. After each production I finish I realize how much I still do not know. And how many things I would like to try. I guess in my CG Sup and generalist world, being an artist is about learning as much about the latest technologies and production cycles as I can, then putting that in practice. Having said that, I do consider myself a cinematographer first, as I have been doing that for about 25 years now.

    Ethan
    Words of true wisdom, the more I know the less I know:) How did you get your start in the industry?
    How did you break into such a competitive field?

    Daniele
    There were not many schools when I started. It was all about a few magazines, some books, and pushing software around trying to learn how to make pretty images. Opportunities opened because of that knowledge! The true break was learning to work hard to achieve a Suspension of Disbelief in my work that people would recognize as such. It’s not something everyone can do, but I was fortunate to not be scared of working hard, being a quick learner and having very good supervisors and colleagues to learn from.

    Ethan
    Which do you think is better, having a solid art degree or a strong portfolio?

    Daniele
    Very good question. A strong portfolio will get you a job now. A solid strong degree will likely get you a job for a longer period. Let me digress here; Working as an artist is not about being an artist, it’s about making money as an artist. Most people fail to make that difference and have either a poor career or lack the understanding to make a stable one. One should never mix art with working as an artist. You can do both only if you understand business and are fair to yourself.



    Ethan

    That’s probably the most helpful answer to that question I have ever heard.
    What’s some advice you can offer to someone just starting out who wants to break into the industry?

    Daniele
    Breaking in the industry is not just about knowing your art. It’s about knowing good business practices. Prepare a good demo reel based on the skill you are applying for; research all the places where you want to apply and why; send as many reels around; follow up each reel with a phone call. Business is all about right time, right place.

    Ethan
    A follow-up question to that is: Would you consider it a bad practice to send your demo reels out in mass quantity rather than focusing on a handful of companies to research and apply for?

    Daniele
    Depends how desperate you are… I would say research is a must. To improve your options, you need to know which company is working on what and what skills they are after. If you were selling vacuum cleaners you probably would not want to waste energy contacting shoemakers or cattle farmers.

    Ethan
    What do you think the biggest killer of creativity and productivity is for you?

    Daniele
    Money…If you were thinking as an artist. ;) If you were thinking about making money as an artist… then I would say “thinking that you work alone”.

    Ethan
    Best. Answer. Ever.
    What are ways you fight complacency and maintain fresh ideas, outlooks, and perspectives

    Daniele
    Two things: Challenge yourself to go outside your comfort zone. And think outside of the box.

    Ethan
    What are the ways/habits you have that challenge yourself to get out of your comfort zone and think outside the box?

    Daniele
    If you think you are a good character painter, pick up a camera and go take pictures of amazing landscapes. If you think you are good only at painting or sketching, learn how to code in python. If you cannot solve a problem, that being a project or a person, learn to ask for help or learn about looking at the problem from various perspectives. If you are introvert, learn to be extrovert. And vice versa. And so on…

    Ethan
    How do you avoid burnout?

    Daniele
    Oh… I wish I learned about this earlier. I think anyone that has a passion in something is at risk of burning out. Artists, more than many, because we see the world differently and our passion goes deep. You avoid burnouts by thinking that you are in a long term plan and that you have an obligation to pay or repay your talent by supporting and cherishing yourself and your family, not your paycheck. You do this by treating your art as a business and using business skills when dealing with your career and using artistic skills only when you are dealing with a project itself.

    Ethan
    Looking back, what was a big defining moment for you?

    Daniele
    Recognizing that people around you, those being colleagues, friends or family, come first.
    It changed my career overnight.

    Ethan
    Who are some of your personal heroes?

    Daniele
    Too many to list. Most recently… James Cameron; Joe Letteri; Lawrence Krauss; Richard Dawkins. Because they all mix science, art, and poetry in their own way.

    Ethan
    Last question:
    What’s your dream job? ;)

    Daniele
    Teaching artists to be better at being business people… as it will help us all improve our lives and the careers we took…

    Being a VFX artist is fundamentally based on mistrust.
    This because schedules, pipelines, technology, creative calls… all have a native and naive instability to them that causes everyone to grow a genuine but beneficial lack of trust in the status quo. This is a fine balance act to build into your character. The VFX motto: “Love everyone but trust no one” is born on that.

     

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    Read more: Ethan Roffler interviews CG Supervisor Daniele Tosti
  • Photography basics: Solid Angle measures

    http://www.calculator.org/property.aspx?name=solid+angle

     

     

    A measure of how large the object appears to an observer looking from that point. Thus. A measure for objects in the sky. Useful to retuen the size of the sun and moon… and in perspective, how much of their contribution to lighting. Solid angle can be represented in ‘angular diameter’ as well.

    http://en.wikipedia.org/wiki/Solid_angle

     

    http://www.mathsisfun.com/geometry/steradian.html

     

    A solid angle is expressed in a dimensionless unit called a steradian (symbol: sr). By default in terms of the total celestial sphere and before atmospheric’s scattering, the Sun and the Moon subtend fractional areas of 0.000546% (Sun) and 0.000531% (Moon).

     

    http://en.wikipedia.org/wiki/Solid_angle#Sun_and_Moon

     

    On earth the sun is likely closer to 0.00011 solid angle after athmospheric scattering. The sun as perceived from earth has a diameter of 0.53 degrees. This is about 0.000064 solid angle.

    http://www.numericana.com/answer/angles.htm

     

    The mean angular diameter of the full moon is 2q = 0.52° (it varies with time around that average, by about 0.009°). This translates into a solid angle of 0.0000647 sr, which means that the whole night sky covers a solid angle roughly one hundred thousand times greater than the full moon.

     

    More info

     

    http://lcogt.net/spacebook/using-angles-describe-positions-and-apparent-sizes-objects

    http://amazing-space.stsci.edu/glossary/def.php.s=topic_astronomy

     

    Angular Size

    The apparent size of an object as seen by an observer; expressed in units of degrees (of arc), arc minutes, or arc seconds. The moon, as viewed from the Earth, has an angular diameter of one-half a degree.

     

    The angle covered by the diameter of the full moon is about 31 arcmin or 1/2°, so astronomers would say the Moon’s angular diameter is 31 arcmin, or the Moon subtends an angle of 31 arcmin.

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