Sizing a deck
To help visualize how a deck will look use some low-tech visual aids. If you're considering a 12-by-20-foot deck, spread a drop cloth that size over the lawn where the future deck will be. Or outline the space with a strung out hose and rakes laid end to end to enclose the space. It's a far cry from virtual reality, but an easy way to get a feeling for how large (or small) the dimensions will translate to.