1st Lesson 07/07/2010
WHAT IS VIDEO-MAPPING?
Video-mapping is a technique that consists of projecting video images on buildings, façades, structures or nearly any kind of surface or object other than the usual flat, rectangular 4-sided screen. Video-mapping is re-designing a space, reconstructing what was already there. It creates astonishing optical illusions and turns reality into something else.
Video-mapping is quite new and is flourishing nowadays. The reason of its success is that the public gets somehow emotionally involved in the show. It is not just “another cool visualization”, but it is surprising and exciting and involves physical as well as virtual space.
One example of a very successful video-mapping is the performance by Etienne de Crécy – Solidays
Another example by the company nuFormer
There are two principal ways of approaching a video-mapping show:
1)-Project images on a surface/façade. Images are projected in the “normal” way, as if the building were a huge flat screen.
2)MASKING. It consists on creating masks (a sort of opacity templates) with the exact shape and position of the different elements of the building/architecture etc. On this masks, or in the space between this masks, is where the video is projected, using a simple alpha-channel technique. This produces the illusion that some parts of the building glow, darken etc.
WHAT DO WE NEED TO MAKE VIDEO-MAPPING?
The most important thing you need is, obviously, a beamer. This beamer or projector must produce a high amount of lumens which makes it possible to produce a clear, accurate image on a big surface and from long distances. Of course the power you need depends on the kind of project you want to make (e.g. the size of the place you want to project on)
Some characteristics of a projector for a video-mapping project:
– Zoom (digital and lens)
– Remote control.
– Lens as wide as possible. Never fish-eye lens
– Resolution of at least 1024 x 768 px
We will also need a photo camera. You should be able to adjust the lens width (a mobile phone camera, or a normal digital camera won´t do). This allows us to change its witdh so that it matches the lens wide of the projector. This is very important, we will explain why later on.
Video-mapping is not a cheap activity. Projectors are expensive equipment: a 10.000 lumen beamer can cost near 10.000€, and you can get an idea of how much it cost to rent such a machine here and here . This being the case, it would be a good idea to contact a sponsor who will fund the project and cover all the expenses derived from the rent of the equipment. Naturally, the client will want to see their logo on the big screen as huge as possible, making it very clear who paid for the whole event. The real challenge comes when the artist is able to do something beautiful, artistic and professional, and at the same time satisfy the client.
VIDEO-MAPPING IS GREEN AND CLEAN
Indeed: apart from the unavoidable waste of energy necessary to project the images, you don´t need any kind of inkt, paint or chemical component to modify the builiding/space/object. Another advantage of video-mapping is that it does not damage in any form the building you project on, and once the magic is, everything remains as it was.
MANAGEMENT OF A PROJECT
Video-mappers, like vampires, work at night. Or, if that´s not possible, they try to make their work space or studio as dark as possible. They are patient creatures and their first commandment is: setting up consumes a great deal of the time.
First of all, you have to place the projector exactly in front of the object you want to project on. You can also use a bubble level to make sure that the position of the beamer is perfectly horizontal. Once the beamer is placed, and the cables have been carefully taped and protected, it will be absolutely inmovable! No one should ever try to touch the projector, or the cables, and if you need to turn it on or off, then you use the remote control. This is a very important thing, because it could ruin hours of work. It is also important to know that a projector is very sensitive to vibrations and weather conditions. You don´t want to see an ugly jittering image right in the climax of your show, and likewise you don´t want your 10.000€ baby get ruined by the rain…so you should take measures and find a suitable stand and weather protection for the projector.
2)MAKE THE PHOTO
Next, you take a photo of the building/space you are going to project on. This photo will serve you to get a image from which you will obtain the different masks/shapes of the building.
First of all, you make sure that the angle of the camera matches exactly the angle of the projector´s lense. Then you place the camera beside or on top of the projector lense, and make the photo: this way you get the closest image possible to what the projector “sees”.
Here you can see different examples of succesfull and unsuccessful photos:
In ‘map picture number 1’ and ‘map picture number 2’ we can see 2 examples of bad camera positioning . These are the pictures Olga Westrate took from a different angle from the beamer lens.
Even if she was using a good camera in picture number 2 and a wide angle one from her phone in picture number 1 the object is not matching the beamer lens throw.
In map picture number 3 the picture highlighted in red shows a good positioning and its matching our guide picture.
Richard Neef used the same position of the beamer and he was using a simple digital camera.
3)CALIBRATION OF THE PHOTO
Once we have the right photo, we open a photo editing software like Photoshop, GUIMP (open source program very similar to Photoshop), iPhoto etc, and we set the size of the photo to our projector´s resolution (in this case, 1024×768 px). Then we set the view to 100% and we project the image back into the object. You will clearly see if the photo is calibrated (every element in the photo matches the real building), and you can make small retouches so that everything matches perfectly.
4)CREATING THE MASKS
This you can do with any program you are familiar with: After Effects, Illustrator, Photoshop, GUIMP… You “cut out” de different elements of the image and create masks (templates) in different layers, one for each mask. There are hundreds of tutorials in the web about how to create masks, here some of them:
Once you have your masks, you export them separately. We get something like this:
Now the real fun begins. We have our masks, and it is time now to decide what we are going to do with them. Video-mapping is not restricted to any particular software at all. You should just use the program you use for your animation/film/video stuff, like for example:
-Adobe After Effects
Just use your creativity, make a little plan of what you want to do and… we´ll see the results in the next lesson!