For instance, if a wizard has a magical photograph of a place, but has never been there physically, can he Apparate there by just focusing on the picture?
Yes, it seems possible to Apparate to a place you’ve never been.
Narcissa Apparates to Snape’s house, and Bellatrix follows her, trying to stop her sister from betraying the Dark Lord’s confidence. Bellatrix Apparated separately from Narcissa.
“With a second and louder pop, another hooded figure materialised.
- Harry Potter and the Half-Blood Prince, Chapter 2 (Spinner’s End)
It’s very clear when Bellatrix arrives at Snape’s house, she didn’t know what to expect. She was surprised to see that Snape lived in such a place. In addition, she said she suspected none of her kind had ever set foot there, which she probably wouldn’t say if she herself had been there before.
“He lives here?’ asked Bella in a voice of contempt. ‘Here? In this Muggle dunghill? We must be the first of our kind ever to set foot –”
- Harry Potter and the Half-Blood Prince, Chapter 2 (Spinner’s End)
She seems surprised as well as disdainful, so she probably had never seen Spinner’s End before.
There is clear canonical evidence that it is possible to apparate to a never-visited location.
Goblet of Fire Chapter 6
“Where ’re Bill and Charlie and Per-Per-Percy?” said George, failing to stifle a huge yawn.
“Well, they’re Apparating, aren’t they?” said Mrs. Weasley, heaving the large pot over to the table and starting to ladle porridge into bowls. “So they can have a bit of a lie-in.”
It is apparent that they have never visited the location of the Quidditch World Cup, based on Mr. Weasely's later comments:
So we had to find a nice deserted moor, and set up as many anti-Muggle precautions as possible.
Why would they have previously been to the deserted moor?
I believe there’s a handy wood they’re using as the Apparition point.
Or why would they have ever been to the handy wood?
Furthermore, in that same discussion Charlie's failure is described:
“Charlie had to take the test twice,” said Fred, grinning. “He failed the first time, Apparated five miles south of where he meant to, right on top of some poor old dear doing her shopping, remember?”
Had Charlie ever previously visited the exact spot that he accidentally ended up in?
The Death Eaters were able to apparate to the graveyard when Voldemort regained his body, even though there is no reason why any of them would have been there before. It was clearly not their regular meeting place, as Voldemort states:
“My father’s bone, naturally, meant that we would have to come here, where he was buried.
Ron as well apparated places he had never been to previously. When he rejoins Harry and Hermione in the Forest of Dean (Deathly Hallows Chapter 19) he tells them:
I didn’t do it so well, Splinched myself again” — Ron held up his right hand to show two missing fingernails; Hermione raised her eyebrows coldly — “and I came out miles from where you were. By the time I got back to that bit of riverbank where we’d been ... you’d gone.”
He had obviously never previously been to a place miles away from a riverbank that he had only visited for the first time when they were camping there.
Just a few pages later he describes how he apparated to multiple places he had never been before:
“It sort of floated toward me,” said Ron, illustrating the movement with his free index finger, “right to my chest, and then — it just went straight through. It was here,” he touched a point close to his heart, “I could feel it, it was hot. And once it was inside me I knew what I was supposed to do, I knew it would take me where I needed to go. So I Disapparated and came out on the side of a hill. There was snow everywhere.
“We were there,” said Harry. “We spent two nights there, and the second night I kept thinking I could hear someone moving around in the dark and calling out!”
“Yeah, well, that would’ve been me,” said Ron. “Your protective spells work, anyway, because I couldn’t see you and I couldn’t hear you. I was sure you were around, though, so in the end I got in my sleeping bag and waited for one of you to appear. I thought you’d have to show yourselves when you packed up the tent.”
“No, actually,” said Hermione. “We’ve been Disapparating under the Invisibility Cloak as an extra precaution. And we left really early, because, as Harry says, we’d heard somebody blundering around.”
“Well, I stayed on that hill all day,” said Ron. “I kept hoping you’d appear. But when it started to get dark I knew I must have missed you, so I clicked the Deluminator again, the blue light came out and went inside me, and I Disapparated and arrived here in these woods. I still couldn’t see you, so I just had to hope one of you would show yourselves in the end — and Harry did. Well, I saw the doe first, obviously.”
Of course it is possible that the Deluminator had something to do with it, but the Deluminator is an invention of Dumbledore's which means that the "magical technology" for apparating to unknown places must actually exist in some form.
(Snape also arrived at the Forest of Dean, and while it doesn't say explicitly that he apparated, it seems a pretty safe assumption that he did so.)
Dumbledore apparently apparated to Privet Drive the night he left Harry there.
Philosopher's Stone Chapter 1
A man appeared on the corner the cat had been watching, appeared so suddenly and silently you’d have thought he’d just popped out of the ground.
Is there any reason why he would have previously visited it? Indeed we are immediately told:
Nothing like this man had ever been seen on Privet Drive.
This would not be true if this very man had been there previously (unless "seen" is taken quite literally and on his previous visit no one had seen him).
The Snatchers appeared mere moments after Harry used the tabooed name of Voldemort, which indicates that they apparated, yet they obviously hadn't previously visited whatever random location the trio was using as their current hideout.
Harry apparates to Shell Cottage despite never having been there before.
Deathly Hallows Chapter 23
“Ron, catch — and GO!” he yelled, throwing one of the wands to him; then he bent down to tug Griphook out from under the chandelier. Hoisting the groaning goblin, who still clung to the sword, over one shoulder, Harry seized Dobby’s hand and spun on the spot to Disapparate.
As he turned into darkness he caught one last view of the drawing room: of the pale, frozen figures of Narcissa and Draco, of the streak of red that was Ron’s hair, and a blur of flying silver, as Bellatrix’s knife flew across the room at the place where he was vanishing —
Bill and Fleur’s . . . Shell Cottage . . . Bill and Fleur’s . . .
He had disappeared into the unknown; all he could do was repeat the name of the destination and hope that it would suffice to take him there. The pain in his forehead pierced him, and the weight of the goblin bore down upon him; he could feel the blade of Gryffindor’s sword bumping against his back; Dobby’s hand jerked in his; he wondered whether the elf was trying to take charge, to pull them in the right direction, and tried, by squeezing the fingers, to indicate that that was fine with him. ...
And then they hit solid earth and smelled salty air. Harry fell to his knees, relinquished Dobby’s hand, and attempted to lower Griphook gently to the ground.
When Harry and Dumbledore visit Slughorn's house, Harry asks why they didn't just apparate directly into the house.
Half Blood Prince Chapter 4
“Because it would be quite as rude as kicking down the front door,” said Dumbledore. “Courtesy dictates that we offer fellow wizards the opportunity of denying us entry. In any case, most Wizarding dwellings are magically protected from unwanted Apparators. At Hogwarts, for instance — ”
“ — you can’t Apparate anywhere inside the buildings or grounds,” said Harry quickly. “Hermione Granger told me.”
The implication here is that if not for special anti-apparition protection and courtesy, they could theoretically apparate directly into the house. Yet Dumbledore has presumably never been there before, as Slughorn says:
I’ve been on the move for a year. Never stay in one place more than a week. Move from Muggle house to Muggle house — the owners of this place are on holiday in the Canary Islands — it’s been very pleasant, I’ll be sorry to leave.
It appears yes.
I can think of some examples: the rock Harry and Dumbledore Apparate to to get to the cave for the Horcrux. Whilst discussing the Horcrux memory with Harry Dumbledore says this at one point:
'Correct,' said Dumbledore. 'I have been looking for a very long time. I think . . . perhaps . . . I may be close to finding another one. There are hopeful signs.'
'And if you do,' said Harry quickly, 'can I come with you and help get rid of it?'
This strongly implies that Dumbledore has never been to the place; he knows about it because of Ms. Cole but nowhere in canon can I think of that suggests Dumbledore has actually been there; certainly he's never been to the cave and this suggests that he hadn't been by the cave either. And at this point he believed he had found one and he saw hopeful signs but that doesn't mean it is certain - yet (as we find out later it is although the original locket had been stolen). In the chapter The Seer Overheard there is this dialogue between Harry and Dumbledore:
And then Harry remembered why he had been eager to come to Dumbledore's office in the first place. 'You've found one? You've found a Horcrux?'
'I believe so.'
Rage and resentment fought shock and excitement: For several moments, Harry could not speak.
'It is natural to be afraid,' said Dumbledore.
'I'm not scared!' said Harry at once, and it was perfectly true; fear was one emotion he was not feeling at all. 'Which Horcrux is it? Where is it?'
'I am not sure which it is — though I think we can rule out the snake — but I believe it to be hidden in a cave on the coast many miles from here, a cave I have been trying to locate for a very long time: the cave in which Tom Riddle once terrorized two children from his orphanage on their annual trip; you remember?'
It is true that he used the word been as in past tense but as a literal thinker I try remembering that most don't interpret things that way; even so though he hasn't been to the cave and would he have gone to the rock? I don't think that's really the case because if he had he'd already been able to verify the cave is indeed there.
'Yes,' said Harry. 'How is it protected?'
'I do not know; I have suspicions that may be entirely wrong.' Dumbledore hesitated, then said, 'Harry, I promised you that you could come with me, and I stand by that promise, but it would be very wrong of me not to warn you that this will be exceedingly dangerous.'
The above dialogue suggests that Dumbledore is still uncertain on the matter. And how do they get to the area? By Apparating:
'Professor,' said Harry quietly, as the gates at the bottom of the drive came into view, 'will we be Apparating?'
'Yes,' said Dumbledore. 'You can Apparate now, I believe?'
'Yes,' said Harry, 'but I haven’t got a license.'
He felt it best to be honest; what if he spoiled everything by turning up a hundred miles from where he was supposed to go?
'No matter,' said Dumbledore, 'I can assist you again.'
'It will not be necessary for us to enter,' muttered Dumbledore, glancing around. 'As long as nobody sees us go . . . now place your hand upon my arm, Harry. There is no need to grip too hard, I am merely guiding you. On the count of three . . . One . . . two . . . three . . .'
Harry turned. At once, there was that horrible sensation that he was being squeezed through a thick rubber tube; he could not draw breath, every part of him was being compressed almost past en- durance and then, just when he thought he must suffocate, the in- visible bands seemed to burst open, and he was standing in cool darkness, breathing in lungfuls of fresh, salty air.
Harry then questions that the orphanage took the orphans there; Dumbledore explains not precisely: there is a little village by there and they were taken to the sea. Only strong mountaineers would have been able to get to the cave; boats would not work because the waves are too strong. Dumbledore expects that Riddle would have used magic to climb down and so only his two victims and he himself visited it at the time. Certainly Dumbledore had never been to the cave itself and given the obstacles to get to the cave it seems to me he had never been to the rock either. He certainly had been to the orphanage but nothing suggests he had been to exactly where they Apparated to. Is it close enough that it works fine? Possibly but I'll return to this when I discuss the Three D's.
Hermione and Harry Apparate to Godric's Hollow in Deathly Hallows; just like Harry was too young to really understand death when his parents were killed (thus at Godric's Hollow) I'm certain that Hermione had never been there either. Hermione certainly hadn't been around the graveyard as Hermione earlier questions whether his parents would be there:
'I'm sure it is,' said Hermione, her eyes upon the church. 'They . . . they'll be in there, won't they? Your mum and dad? I can see the graveyard behind it.'
There is no canon instance that I can think of where Hermione had been there at all and Harry hadn't been there since his parents were murdered yet they Apparated there.
But what about the Three D's?
'The important things to remember when Apparating are the three D's!' said Twycross. 'Destination, Determination, Deliberation!'
'Step one: Fix your mind firmly upon the desired destination,' said Twycross. 'In this case, the interior of your hoop. Kindly concentrate upon that destination now.
There seems to be some ambiguity but at the same time there are examples where it's suggested someone Apparates to a place they've never been to before. But does concentrating on the destination mean visualising it? That isn't specified here (see below) and one could easily argue that it's the place whether they've been there or not. But then what about determination?
'Step two,' said Twycross, 'focus your determination to occupy the visualised space! Let your yearning to enter it flood from your mind to every particle of your body!'
So let's say it's more than the place name: it's what it looks like. Do you need to have been somewhere to visualise it in your head? I certainly don't if I've seen photos or videos of it - and I remember it well enough. I can also visualise places I've read enough about; and it can be sure that Hermione read about Godric's Hollow, for example.
What this comes down to is it is suggested that some have Apparated to places they've never been to (or if they have it's not been noted prior to it) but it does require visualising the place. But there are different ways to think of visualisation and in the case of what it looks like we don't even need to have been there do we? And as our Miss Bella above reminds us Bellatrix was surprised where Severus lived and they did Apparate there; and since Bella and Narcissa Apparate separately we cannot say she had ever been there. It seems to me then that yes you can Apparate to places you've not personally visited.
Finally it can be sure that Dobby had never been to Shell Cottage before taking everyone from Malfoy Manor there (or around it). But since Elf magic is different that might not count.