03 June 2012

Sebastian König - Blender Green Screen Keying Concepts - Tutorial Video Review

Whenever Sebastian König comes out with another Blender video tutorial, I know that I will have the next few hours of my day planned out for me. So when I found out the that Mr König had put out a Keying/Green Screening tutorial off I went to purchase the video.

Product Specifications:
  • Name: Blender GreenScreen Keying Concepts
  • Author: Sebastian König
  • Price: $19.95 (29 Jan 2011)
  • Type: Streamable Tutorial Video
  • Length: 1 Hour 48 Min Roughly
First thing to note is that this tutorial video covers how to use Blender Compositing Node system to produce Mattes/Keys from a green/blue/red screens, using various techniques. A feature which is vital if you want to extract live action footage from a scene and composite different elements together.

Chapter Sections:
  • Chapter 1 - Getting Started (Video Position 00:00:00)
  • Chapter 2 - The Channel Key (Video Position 00:13:40)
  • Chapter 3 - Your Own Custom Key Key (Video Position 00:24:18)
  • Chapter 4 - Lightwrap (Video Position 00:32:54)
  • Chapter 5 - Garbage Mattes (Video Position 00:47:17)
  • Chapter 6 - Channel Blur (Video Position 01:01:01)
  • Chapter 7 - Rotoscoping (Video Position 01:11:42)
  • Chapter 8 - Compositing (Video Position 01:26:05)
This video is the second in the series of CMIVFX tutorials covering the topics of how to use Blender to carryout various studio level production tasks using Blender's Compositing system. The previous tutorial (Blender 3D Compositing also produced by Mr König is related to this video and it would be useful to have seen that previous video because some of the topics covered are easier to understand having seen the previous video. But if you are not totally new to Blender or Blenders Node editor you should be able to follow along without any difficulty even if you haven't seen the earlier tutorial.

The production quality of the video tutorials is very high and encoded very clearly so there should be no problems viewing the streaming video from their website. I had been busy and had to be away from the web for a while so I downloaded the video and watched it from within VLC, again it was very clear and easy to watch.

Chapter 1 - Covers the initial setup of Blender and its interface, going over how to get various still and movie sequences into Blender Compositing system so as to allow you to do the various Keying processes. Throughout the tutorial various 2k and 4k files are used (studio quality). For those that do not know the theory of how GreenScreens work Mr König describes briefly the theory of how they work. After the theory a few ways that could be used to make Mattes/Keys are described and Mr König explains how they work and explains how they are not useful for the needs of this tutorial.

Chapter 2 - Having covered some of the bad ways to pull a Matte from images in Chapter 1, Chapter 2 covers better methods using Blender Channel Key Node. Covering how to pull Mattes from both still and moving images with and without the effects of motion blur upon the images. After all, it's all very well to pull a Matte from a still none motion blurred image, but when the images are moving, dealing with the problems motion blur introduces is very important and it is explain and handled very well by Sebastian. Sebastian shows both how to use the nodes to manually pull a Matte using Nodes, as well as Nodes that do it automatically. Often tutorials just mention the automatic ways to pull Mattes rather than explaining how it all works, the flexibility that is afforded in understanding exactly how things work makes you much more likely to be able to pull more difficult Mattes in future. The methods used throughout all the chapters remind me a lot of a book "Steve Wright - Digital Compositing For Film And Video" another excellent source of digital compositing information, which is much easier to follow when in video form as this tutorial is.

Chapter 3 - Covers making a custom made Matte puller using Blender Node system, useful when over methods that Blender provides do not automatically work as required. This section is fairly involved but was clear and easy to follow.

Chapter 4 - After having pulled at Matte from the previous chapter, Lightwrapping are explained and then a demonstration of how to create them are gone over. After lightwrapping is covered, a simple method of making Vignettes are demonstrated. This time however the shots that are being processing are more difficult as it has a drummer drumming which has large amount of motion Blur and simpler Matte pulling methods are not sufficient.

Chapter 5 - Covers the uses of Garbage Mattes and how to combine multiple Garbage Mattes to achieve a clean Matte pull on different parts of a short, as different parts of the short required different methods to get clean results. Excellent demonstration of how to use Blenders mask like features to achieve the result needed.

Chapter 6 - Channel Blur is a slightly advanced chapter because it covers how to take lower quality GreenScreen shots which are pixelated/lower resolution, and uses various YCbCr colorspace tricks to fake a higher resolution Matte. How the trick works is very well explained although it would have helped to have had more information on exactly how the YCbCr color system works, though enough information was given to be able to carry out the color channel blurring trick, and if your really want to know all the detailed specific of YcbCr Colorspace you can always do a google search. This is a very useful technique, makes me wish Blender had an inbuilt automatic node for doing this trick as standard. A really useful website (www.hollywoodcamerawork.us) is mentioned that hosts many different GreenScreen stills and movies. The images used in this chapter have a woman with a transparent veil dancing around, and as a result it's a much harder task to pull a clean Matte, but Sebastian demonstrates how to do it efficiently with multiple Garbage Mattes and Masks from within Blender.

Chapter 7 - Rotoscoping, follows on from the previous chapter. Because the woman is dancing, an animated Garbage Matte is created using Blender RotoBezier feature, using this method Sebastian demonstrates the usefulness of Rotoscoping and Blender RotoBezier feature.

Chapter 8 - Compositing, this final chapter composites the Keyed images that were obtained from the previous chapters, using Blenders Compositor. Using the Images as Planes addon method of positioning extracted GreenScreened footage into Blender 3D Viewport is explained. Another useful trick described is recoloring of extracted GreenScreen material.

Each chapter is very well explained and there are numerous examples of how to use the various techniques described throughout all the chapters. Sebastian paces his descriptions of that various tasks in each of the chapters very well.

This tutorial stands well on its own or with the previous Compositing tutorial that Sebastian did. It in my opinion is well worth the money and very informative and full of useful tricks and tips. It will almost certainly have something useful in it for someone looking to improve their GreenScreen/Matte pulling skills.

Review Score 86%