There are some great optical illusions posted on YouTube, but we have to say that this is one of the best. YouTube user brusspup has created a picture of a cartoon T-Rex that seems to follow you around the room with its head as you move.

The resulting video is fantastic as we get to see first one small version of the illusion, then several at once, which still follow the camera as it rotates around them. A massive one is next, proving that the illusion works even better the larger the picture. And then we get to see how it is constructed.

"I've always wanted to try this illusion with several of these at once. I wanted to use 20 or 30 but after I tried a test with only 12, I realised 20 or 30 was going to be too many. So another thing I've always wanted to try was to have a large version," said the poster.

"The original file was about 9ft X 9ft. I had to split the image into four files so the printer at my local print shop could print it. I traced all of the pieces on cardboard, which I used to build a support structure for the prints. I used small pieces of cardboard and hot glue to make the structure really solid.

"One problem that I had was that the paper for the large dragon was really shiny. So if you look closely you can see the reflection of the eyes on the "top" and side panels. I bought some matte spray to try to minimise the reflections. It worked a little. Over all I was happy with the results."

Brusspup is an originator of several illusions posted on YouTube and has also posted the image for you to print out and recreated yourself. Check out his Illusions and Science YouTube channel for more.