O is for OMG


I must admit, there isn’t that much in the technology world that wows me these days. Computers get smaller and faster and yet there are those days where you see something cool that you just have to share. Let’s get to it…

Retro-reflective Chroma Key

I remember the old Wild West movies where the scenery as on a roll and the actors would ride their horses and the camera would roll and it would look almost realistic.

In the modern movie industry as well as in TV (like the weather presenter) they use a system they call a green screen and then use chroma key to key out that colour from the scenes that can be used as a mask to display a different scene. This is how the weather would appear in front of the camera.

You would have seen action shots where superman’s cape would flutter, this was someone in a green suit with a green mask that would be invisible to the camera moving the cape as if the wind was blowing it. Other clever camera tricks are performed using green screen. However, on the set of The Matrix, they used a magenta screen because it would work better for their filming as nobody would be wearing that shade or even close to it on set.

In the editing process, a technology called chroma key is used to turn the solid colour into a black mask that is used to replace the mask with the scene that the editor wants to portray, and when the movie is played, everyone sees what they think is real.

Green screens are quite expensive and can have unintended consequences. If the person being filmed has blonde hair, a green screen can make their hair look unnatural as you can see green through the strands.

Enter retro-reflective chroma key. This uses inexpensive reflective sheet that is commonly used on high-viz uniform stripes that is laid out as a backdrop. The light source for the camera is a ring of coloured LED lights that cause the retro-reflective material to reflect the same colour,but unlike with green screen, the colour can be changed based on what the actor is wearing as the software can be tuned to the colour of the LED lights. The colour of the LED lights can also be changed easily.

There are commercial versions of this that cost thousands to buy, but with a few parts it makes an interesting DIY project.

Since you have ultimate control of the build, you can make the mount tailored to your exact needs. As a ring for your laptop or portable for you to take on a shoot anywhere.

Share this post with your friends