Dimension Door Issue

I would note that lack of clarity in 5e rules is to some degree intentional, as they wanted 5e to get away from rather gamist design of 3e and 4e, but they sometimes make the mistake of trying to have it both ways -- they try to be simultaneously clear and informal, and manage to be neither (the reason you construct formal languages is because doing so assists in giving text clear and unequivocal meaning).

How can you visualize or describe something you never saw, and never been to that location. 
It would be a guess.

Quote from sevidz >>

How can you visualize or describe something you never saw, and never been to that location. 
It would be a guess.

 Your player guessed the location:

Quote from zastrixarundell >>

[...] 

You arrive at exactly the spot desired. It can be a place you can see, one you can visualize, or one you can describe by stating distance and direction, such as “200 feet straight downward” or “upward to the northwest at a 45-degree angle, 300 feet.”

The argument was that I could describe the end position by seeing the corner of the building (the top-left corner of the gray block) and going a few feet behind it. [...] 

Quote from sevidz >>

How can you visualize or describe something you never saw, and never been to that location. 
It would be a guess.

Again, the spell explicitly says you can choose a location based on a direction and distance from your current position, without needing to be able to see or describe it. 

With all due respect, it is starting to seem like you're deliberately ignoring the part of the spell description that contradicts your position.

Quote from sevidz >>

How can you visualize or describe something you never saw, and never been to that location. 
It would be a guess.

 You can imagine that there's probably something behind the locked door or barrier you want to get past. If there isn't, then you're taking the damage, but otherwise you can get past it. Or you can just say "10 feet thataway!" and ignore the imagination part entirely. This is the point of the spell.

Quote from sevidz >>

How can you visualize or describe something you never saw, and never been to that location. 
It would be a guess.

You don't have to. You have to describe where you want to go. Here is the wording of the spell: " It can be a place you can see, one you can visualize, or one you can describe by stating distance and direction, such as “200 feet straight downward” or “300 feet upward to the northwest at a 45-degree angle.”

As such, your player is completely in the right here, and you are very incorrect. He describe where he wanted to go by stating "that point I can see, but one meter to the left. Even though he does not know exactly what is there, that does not matter to the spell, because he knows where he wants to go and can describe how to get there.

Quote from sevidz >>

How can you visualize or describe something you never saw, and never been to that location. 
It would be a guess.

Being able to visualize the destination is only one of THREE separate ways to tell the spell where you want to go

You teleport to a location within range. You arrive at exactly the spot desired. It can be 1) a place you can see, 2) one you can visualize, or 3) one you can describe by stating distance and direction, such as “200 feet straight downward” or “300 feet upward to the northwest at a 45-degree angle.”

1) You can see the destination -- say, the front door of a building a couple hundred feet away
2) You can visualize the destination -- say, a room you've been to before that's inside the building
3) You can describe the distance and direction you would travel to get to the destination -- say, 10 feet past the back corner of the building and 10 feet to the left

All of those are explicitly allowed by dimension door

Sevidz is wrong on every count.  Plain and simple.  Specific rules beat general rules every time.  For example, Poison Resistance is a general rule.  However, the Poison damage from an Assassin Rogue's ability ignores that.  So it is with Dimension Door.  The specifics of the spell overcome any general rules about spellcasting and/or teleportation.  The rules table he added is specifically for the spell Teleport and no other spell.  He's also wrong about the target of the spell; it's not the location, it's the caster.

"You teleport to a location within range. You arrive at exactly the spot desired. It can be a place you can see, one you can visualize, or one you can describe by stating distance and direction, such as “200 feet straight downward” or “300 feet upward to the northwest at a 45-degree angle.”

-You teleport to a location within range.  You arrive at exactly the spot desired.

Full stop.  No other requirements needed.  No line of sight, no prior knowledge of the location, etc.  It can be a place you can see OR one you can visualize OR one you can describe.  You can easily visualize and/or describe the location that is 10 feet around a corner.  

When we solicit the Internet for advice, sometimes we are a little embarrassed by the answers provided. Especially when we invite our players to the public discussion. A good DM will swallow the wounded pride, accept when they are wrong, and move on. Being the DM means you have to be wrong sometimes, but it is best when you don't try to stay wrong. 

Look if you truly do not want the character to dimension door to that specific spot just put something there.

The spell states the castor can use direction and range, only, to port to a new area. Just put a tree in the area that he can not see.

But I have used DD to teleport to someplace in the air above my target area and used feather fall to safely land.