Does length dilation affect the Y axis in the Nether?

It's known that traveling one block in the Nether is equivalent to traveling 8 blocks in the real world, and I can confirm that along the X and Z axes by building four portals: two in the Nether and two in the real world.

But I can't seem to corroborate the length dilation from the Nether to the real world along the Y axis (height).

That is, if I build the following portals:

• Nether:
• Portal 1 at n height
• Portal 2 at n - 8 height
• Real world:
• Portal 3 at m height
• Portal 4 at m - 64 height

I expect Portal 1 and 3 to link up while portal 2 and 4 should link up. But in my testing, if I use portal 1 or 2, they lead to portal 3, and if I use portal 3 or 4, they lead to portal 2.

Is there any evidence—in the form of a video, a world save file, or notch—that one nether block equals 8 real world blocks along the Y axis? I'm trying to determine if my error is in calculation or if it's in execution.

``````    Y
│
│      XYZ reference system
└───X  for this question.
╱
╱
Z
``````
• @Arda it's the coordinate system Minecraft uses.
– user3389
Commented Dec 18, 2010 at 18:45
• @Arda: Alpha Level Format, Chunk File Format, NBT File Format. People familiar with the issue know that Y = height, it's explained in the question itself, and it's tangential to the question so I don't see why this is an issue.
– user3389
Commented Dec 18, 2010 at 19:06
• @Mark It is a tad hard to answer the question "Does length dilation affect the Y axis in the Nether?" when you're assuming that Z is elevation. It was just confusing. It wasn't explained in the question until @badp edited it (ie. when I placed my comment)
– user56
Commented Dec 18, 2010 at 19:42
• @Arda it was explained in the question before badp added the diagram (of which I'm appreciative nonetheless): "along the Y axis (height)". Stack Exchange is for questions to be answered by experts, right? A Minecraft expert is not and would not be confused by the coordinate system used in the question: it's pretty standard knowledge for those delving into the mechanics of the engine.
– user3389
Commented Dec 18, 2010 at 19:52
• @Arda Why would a Minecraft player who does not have technical knowledge of the engine answer a question that's about technical knowledge of the engine?
– user3389
Commented Dec 18, 2010 at 19:54

According to this thread in the Minecraft Forums that seems to have peeked into the code, length dilation does not affect the y-axis.

http://www.minecraftforum.net/topic/345806-nether-portal-science/

Summary version

• Calculate coordinate of destination based on entry coordinate. (X, Y, Z) <---> (X*8, Y, Z*8)

• At destination, look for the closest active nether portal within a 128 block radius of the player (257x257x128 area centered on destination) (the Euclidean distance (the 3D distance)). Teleport player there if one exists.

• If no portal exists in the 128 block radius, the game creates one by looking for the closest possible nearby position within a 16 radius column (33x33x128 area) that has enough space to spawn a portal. And teleports the player there.

• And if there's no possible spawn position with solid ground, it just creates a portal at the destination anyway, converting any blocks in the way into a portal.

According to the wiki:

If you place two portals on top of one another you will come out of the bottom one on the overworld and the top one in The Nether.

I read somewhere (I'm afraid I can't remember where) that a portal will always(?) connect to the nearest portal in the other world. Thus, the Overworld portals should connect to the nearest/highest Nether portal and the Nether portals should connect to the nearest/lowest Overworld portals.