The Problem with your Visual Memory
When remembering what we saw in the past, we are pulling from our imperfect, limited visual memory. And unless you have spent a focused time studying and analyzing your subject and were able to remember it, it is very likely that you don't know all the relevant details needed to recreate it. Inevitably, there will be many elements of the full picture that you won’t be able to recall.
This is not an arbitrary imperfection; in fact, visual memory needs to be limited, allowing your brain to be economical with the information it stores by remembering the “gist” of an object while omitting detail . Simply put, remembering everything would be impractical and just clutter up your brain’s RAM.