Dan Hume's Blog


green screen and compositing in after effects
February 26, 2010, 12:37 pm
Filed under: After Effects, Green Screen, Post Production Techniques

Green Screen

A chroma key, sometimes called a green screen, is a device used in film and video production. The screen itself can actually be either green or blue. The editing program will recognize the specific color of the green screen and replace anything in the image that is that color with whatever image you choose. So if the subject is a person, you can put that person in any and every location from the comfort of your studio.

Setting Up

It is important when setting up your green screen that you get the fabric as wrinkle free as possible. The most effective technique is to use a steamer. Make sure it is hung evenly and that there are no unnecessary folds. Wrinkles and folds can cause disruptions in the image once it is placed over the green screen in post production. Also make sure no part of the subject is green including clothing and props. If there’s a similar color it might display the background image instead of the subject. This is why there is a blue side. Also when you place the subject in front of the green screen, make sure there is enough separation so you can light the subject and the green screen separately. Lastly, it’s good to make sure you have a quite a large green screen so that you can have some extra space for a subject that moves a lot.

Lighting

It is critical to light the green screen and the subject separately. Light the green screen first. Any shadows on the green screen will not key correctly and will cause holes in your image. No part of the green screen should look brighter than any other part. This means you need multiple lights. The simplest lighting technique is to place one light on each side of the screen. Next light your subject, taking careful precautions to ensure the lighting of your subject does not interfere with the lighting of the green screen.

Preparing for Post Production

Besides proper lighting and set up of a green screen, there are also some important considerations in order to have a solid product after post production. Consider the perspective of the subject compared with the image that will be displayed in the background. Otherwise the subject might look to big or too small to mach their background. Also if the subject is lit brightly, but the background is at night time, it won’t look good. Match the lighting of the subject in the studio to the lighting of the background it’ll be in front of. Depending on the editing program you use there will be options that allow you to tweak the effect. Experimenting with a sharper contrast is usually one of these options and can make a big difference on screen.

Keying in After Effects

Last week we did some filming on green screening just to try it out. Today we used that footage to import into after effects and had to key out all the green background. There were two methods to this. The first was using the Colour key which requires you to adjust some settings until you get as much of the green to disappear. It’s quite fiddly to remove all the green without effecting the main subject of the footage.

The most effective way of keying out all the green was using the Keylight plugin which pretty much removes all the green on the footage that I have got. It all depends on how well the green screen was lit for the keylight to effectively work its magic.

Before keying out the green screen

Green screen keyed out using Keylight

I imported a photo I took of Bournemouth beach as the background for the video. I realized the lighting on myself, in the video, is not correct to how the light is prjected in the image. This is why i added a lens flare to make it look like there was strong light coming the top right.

Creating an iPod advert look

I created two solids, each a different colour. The first solid was orange and I’ve used this as my background colour. The other solid I used was black and I made that my alpha layer which then the main subject from the video footage becomes like a silhouette. It’s a bit rough at first but you can adjust the Screen Matte which removes any of the details that is showing through.

Here is a clip:

I did another version using Sam’s video of him dancing.

This was just a very simple exercise.



Stream live Tv on the net and iPhone
February 26, 2010, 1:27 am
Filed under: General

I don’t know if this is old news or not but I’ve just discovered this website which allows you to stream live TV to any computer, games console or even an iPhone with an internet connection. It looks like its still being developed because they are already in the process of adding HD channels in the near future. I have just signed up and have started watching some TV on my iPhone and the quality is brilliant. Watching TV through my iPhone is definitely, in my opinion, a new experience. TVCatchup is the new way to watch your favourite UK television programmes… for free!

Click on the image below to check it out:



new texture
February 25, 2010, 4:44 pm
Filed under: Maya, Post Production Techniques

I wasn’t to happy with the texture I used before so I started trying out with another texture I created in Photoshop. I decided map the image around the whole of the body.



Maya texturing
February 24, 2010, 8:09 pm
Filed under: 3D, Maya, Post Production Techniques

Today I’ve been doing some basic texturing on my 3D character. I’m sticking with using the color scheme of the Kaboosh logo, which is green, white and brown.

Texturing:

Firstly, I decided to texture the legs. Since the legs were extruded from the main body of the character, I had to go to faces, which allowed to select all the faces of the legs.

Then I went to Rendering Editors, Hypershade. I chose the Lambert texture. I then double clicked on the Lambert 3, which opened up the Material Attributes menu on the side. I Selected the colour I wanted, which I chose white. I made sure I selected all the faces on the legs. Then I went back to the hypershade menu, held click on the left arrow underneath Lambert 3 and chose Assign Material to Selection.

This then changed the legs to white. I did the same process for the arms. For the main body I used a texture that I created in photoshop. The image was a combination of different sized line strips going horizontally and vertically. I wasn’t sure how well this would look once I mapped on the body of my 3D character.

Here is the texture mapped onto the body.

The texture didn’t seem to be any good after it was mapped but I then played around with the 2d Texture Placement Attributes, which allowed me alter the way the look of how the texture is presented on the body.

I decided to map the texture so the lines shape together like this.



Short form Video update
February 24, 2010, 11:25 am
Filed under: Short Form Video

Team Members:

  • Dan Hume (cinematographer/Director)
  • Graham Bowdery (Director/script writer)
  • Oliver Emmett (Camera Operator)
  • Jack Ashley (Boom Operator)
  • Kieran Ayles (Actor)
  • Will Bartlett (Actor)
  • Dan Sullivan (Actor)

Location:

  • Base Room (Interior Location)

We decided that the Base room would make a suitable environment for the terrorists. We’re going to use very dramatic lighting at this location.

  • The Pier

This is the location where the terrorists abduct the lecture. The lecture will be waiting for this girl he is meant to meeting, underneath the pier. We will be shooting alongside with the lecture group at a late evening sort of time.

  • Sopley Air Softing (Exterior location)

This is the exterior location of where the terrorists are based. This is where the last scene will be filmed and when the police raid the location.

Actors:

There are going to be four terrorists. Here are our actors we’ve decided to use.

  • Kieran Ayles
  • Will Bartlett
  • Stephen
  • Dan Sullivan

Props/Clothing:

  • Casual clothing – Shirts and Jeans
  • Balaclavas
  • Three Guns

Special Effects:

  • Green Screen

We will be using green screen for the video that the terrorists make their demands for. This will enable us to create a custom background, which will show the terrorists groups identity ‘The Leet Haxors

Equipment

  • 1 x Green Screen
  • 4 x Redhead lights
  • 1 x HD Video Camera
  • 1 x DV Camera
  • 1 x Boom Microphone
  • 1 x Tripod


Street Artist At Night
February 22, 2010, 10:19 pm
Filed under: Post Production Techniques

Idea Development

After thinking more into this project, I have decided I’m going to try and show what it’s like to be a street artist at work at night. Since it’s not legalized, street artist such as Banksy or Mr. Brainwash (MBW) are constantly taking risks by putting up their work in public places, without being being arrested, although I’m aware MBW has been caught a couple of times… BUT he still carries on regardless. Most of the time when they want to put some art up in a public environment, they’ll do it at a specific time at night where it’s dead, where no-one is likely to be around.

My 3D character is going to be representing a street artist in this piece. I’m going to set the scene by filming static shots of Bournemouth town at night when it’s quiet. Then I’m going to find an alley way where I’ll film the scene for my 3D character to appear. I’d like to use an alley way because they’re dark but they do have small areas of light coming from the street lamps. Where it’s light, is where I’ll film an area for my 3D character to be working.

This photo of an alleyway is how I imagined it to look. I would do a very short bit of filming in this area. Below are a couple of shots I story-boarded that I’m going to use.

The rough shading is meant to show the dark areas in each shot.



Post-Production developmentcrea
February 18, 2010, 9:10 pm
Filed under: 3D, Maya, Post Production Techniques

I’m in the process of rigging my 3D character in maya.

I’m working on the legs and the feet, which have been straight forward to do but I’m having a little trouble doing the reverse foot lock method. This method allows the character feet to slide along the ground. Once I’ve sorted that, I can then move onto:

  • making the joints for the arms (same methods as the leg)
  • create and attach controllers to the rig



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