That is amazing.
My step son is autistic as well and also has a photographic memory.
He always amazes me.
We can take him to a mall where he has never been before and walk around it one time, even two and three story malls, and he will draw an exact schematic of the mall, placing the stores in the exact correct locations and then placing minute small details that we have not seen in windows and such.
When we first saw that he did this we took one of the drawings back to the mall and it was live a map of the place.
Also, if he meets you today for the very first time and only sees you for a moment, and if he meets you again in 10 years, he will remember what color glasses you had 10 years ago, the shirt you were wearing and if you got a hair cut or let your hair grow out.
He remembers details like the color of eyes and things like that.
It is really amazing.