Projection mapping is a creative way to transform buildings and walls into visually stunning elements of decor. This technique turns flat surfaces into displays for 3-D videos. But what if an event is outside, without any walls? That was the challenge for David Corwin of Megavision Arts for a wedding for a member of Qatar’s royal family in November. The wedding for 1,200 guests was to take place in a 53,000-square-foot tent erected on an empty lot on the outskirts of Doha.