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VFX
1.Introduction.
What is a composition of Visual Effects (VFX)?
In this introduction, I will explain what I have learned about composition and visual effects. We must understand that composition is the last step in the entire workflow when taking shots that contain visual effects. This means that all the different materials from other departments will arrive at the composition department. For example, from the 3D department, we get the renders, scenes, and 3D cameras. From the filming department, we get the shots with the actors, both on greenscreen and bluescreen, entire sets or matte painting, and we as compositors have to cut those images and add the above ingredients.
I learned that we have to use the same camera in the same place and lights to record the objects and characters, which will add to the composition. Anything that we notice that does not fit in the image wants to mean an inadequate integration. A job well done by a special effects compositor goes unnoticed.
The VFX department is different from the composition department. The VFX department works on simulations of fluids, particles, explosions, fires, smoke, and more effects that do not correspond to the composition department. Houdini software is the primary tool for those works, although many people use After Effects too. Therefore, a compositor must know how those departments work to achieve an optimal result. The primary tool for compositor is Nuke. These are some knowledge that a good VFX compositor should have: design, concepts arts, storytelling, digital color theory, photography, technical knowledge of the camera, compression video formats, and one of the most important, the behavior of the physical reality of light.
In addition to the lectures, I searched to understand the VFX industry, its standards, the pipeline, and the workflow.
I found the diagram designed by VFX compositor Carolina Jimenez Garcia and Andrew Whitehurst's blog explaining the pipeline flow. Together with the class lecture has helped me understand the whole pipeline process much better.
Carolina Jimenez diagrame
Andrew Whitehurst blog
http://www.andrew-whitehurst.net/pipeline.html
2. Filming the elements: Studio shots and courses.
I'm going to try to recreate a transporting, miniature, and magical transformation effect. The first thing is to record some sequences in the studio. After that, using After Effects, I have edited the shots to get a final video sequence with long and close-ups to work perspective, lights, and edge details.
2.1. In the studio: courses
As one of the essential factors that, as compositors, we must know is the exposure of light, I attended the training given at the University by the Film and communication tutor. In addition to that training, I completed a specific Lighting for audiovisual project course online, to understand better the behavior of the light in the compositor's projects (link below).
To achieve a realistic effect, we must take into account the following technical aspects:
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Eye and camera see differently. The eye reconstructs the objects in our mind, and the camera reconstructs them by sending the light through the lens to the sensor. Therefore, we must consider aspects such as depth of field, angle of view, resolution, sensitivity and dynamic range, vision in stereo, white balance, and color gamut.
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Position is the key farther away the camera is from the object, the more the depth is compressed, and the closer the camera is to the thing, the more the depth is expanded.
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The lens is a framing magnifying the scene, and they don't change the perspective. The distance between camera to object cause the change in the depth perception.
Concepts that I have learned:
The key light
Colour, narrative, and frame. They are all those fundamental concepts that any composer should know. We illuminate with light but also with shadow.
Atmosphere (light and color)
Light (and shadow)
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Illumination style
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Light quality
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Light direction
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Light amount
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Ratio o contrast
Color (tone and saturation) -
In the light
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In the art
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In the dressing room
Camera Narrative
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Narrative style
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Optical language
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Projection format
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Camera
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Composition and framing
Gradients Behaviours
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Light and contrast levels
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Colour correction (tone and saturation)
3. Working with the shots
3.1. Editing the shots in After Effects and learning about timeline, layers and continuity.
3.2. Working in Nuke the format of the footage, fps, and keylight.
Nuke is the standard software used for VFX compositions. In the below video, I show the change of the size of our footage using the reformat node, the standard 25 fps for the final project, and the use of the keylight node to convert out the footage in the alpha channel using any background. We can check footage using the keyboard numbers (1,2,3...) because Nuke assigns those numbers to connect to the viewer. The keylight node has to be adjusted in the screen gain and matte values, and the merge node makes sure the two footages are seen in the viewer.
3.3. BACKGROUNDS
I chose the below photos to be used as background in the compositions. The shot in the studio had a light warmth. Then I matched the colors and adjusted the hue and saturation to get the most realistic effects. In disintegration effects, foreground and background finally matched, the same in the futuristic bus composition, however in the transporting and magic wand composition, the light in the shot was coming from the top, and behind then, the colors did not match very well. I decided to use a different BG where the light was coming from the top and open the illumination angle.
1. Disintegration background compositions.
2.Transporting and Magic wand composition.
I create a first try using the above background. I adjusted the hue and saturation and I noticed that I needed another background and illumination to match it within the croma.
3.The backgroung and foreground of miniature composition matched well with long shot, however I had to adjust hue and saturation to match with the close up shot.
4. Futiristic bus composition. I wanted to do this composition a long time ago. I am currently working in Canary Warf; these are son views from the office. One day I thought if we could use an out elevator or lift, all of my students could have these amazing views of London. So I took some photos, and I designed a composition playing with the backgrounds to match the green screen that I shot in the studio.
4. MATCHING COMPOSITIONS
4.1. Matching Compositions - Nuke
In the video below, I show the steps that I have followed to work in the key-light and match the composition with the background. A transform node is added to the Background so that it can be moved or scaled. The merge node is added so that the background can be seen; after that, we add a reform node to be later able to adjust the blur of the Background. HSVTool is the node that we use to match the foreground and background, and it is added to the end of the composition. Finally, to the reform node, we add a blur node to the output of the Background.
4.2. Matching composition in After Effects - Keying - Rostoscopy - Matching color
I worked on After Effects, the miniature composition with edition, and the close-up shots to have a first idea about the final result.
I made a rotos to get split the house and sky frame by frame. I added a wiggle movement and "giant steps."
The magical transition comes with energy assets with a magic wand using distortion, whirl, bulge, and displacement map effects. To create a realistic atmosphere, I used a colored layer with the same color of the energy assets. I tried a matching color of the shots, adjusting the hue and saturation, and playing with the levels.
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4.3 Final Compositions -Black & White.
1.Disintegration
2.Giant - Miniature
4.Matching color - Nuke
Before starting to work with my footage in Nuke, I did a search for the fundamental concepts of color and how to work with them in the software. 32bit floating, HDR and Linear. I made my own resume below.
32 bits floating
In conclusion: if 8 bits per pixel 2 (white and black) = 256 colors, then if we are working with
32 bits per pixel x2 (white and black) = 4.294.967.296 colors, an impressive number to manage in any computer. The solution for that is the floating math values from 0 to 1, it means that we have many decimals to store colors between 0 value and 1 value.
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Digital images are got through a sampling of reality that is converted into digital information called bits.
In 1 bit there are two image values, black (0) and white (1).
2 bits are 4 values of the image blanck( 0.0 -0.1) and white (1.0 -1.1) etc
In 5 bits we get 16 black and 16 white,32 values.
Each pixel has 32 bits.
It is the amount of RGB + alpha = True Colour.
However, Nuke does not use colour depth but
canals then, it would be 32 bits x canal.
High Dynamic images
HDR: Images with high dynamic range, which means that these images have more color information than they show.
Linear
It is a term used to refer to a math process using colors space.
To obtain a digital image, we have to get certain information from reality and transform it into not very large values on any computer. Therefore, we have to choose specific colors; we cannot use all of them simultaneously. This is what is called a color space, the choice and transformation of colors into mathematical values.
In VFX, color space are used to see colors correctly throughout the entire production.
In the shots of the camera, the representation on the monitors or any other devices that we use to show the work.
As Nuke works in a linear way, we will always obtain a wide range of gray tones proportionally, from black (0) to white (1).
When we work in production, it is essential to ask which color space is used in other departments to adapt our project within that profile.
Workflow
Nuke read the footage, we apply the suitable color space to it, and Nuke transforms into the linear process. We follow working on the composition, and finally, the same color space is applied again in the write node to ensure that we obtain the color space used in the entire production.
References
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