40d:Digging

Digging is a group of actions available from the designations menu. Digging is performed by dwarven miners in order to create empty spaces, hollow out material or dig stairs and ramps. All dig actions require a dwarf with the miner skill and an available pick.

The most basic action is d mine. When this option is selected you can mark areas to be hollowed out from the current layer. Any useful material such as rock or ore is deposited on the ground excavated by the tile. This dig creates a ceiling by preserving the floor on the layer above. The only restriction on digging is the creation of an unstable 7x7 room underground which will collapse after a short amount of time.

A more advanced version of dig is h channel. When this option is selected, floor tiles can be marked for excavation. When dug out (from above) the tile below will be dug out and the floor (or ceiling?) will be removed. Creating a channel could be described as 'strip mining'. Be careful that multiple miners working on the same channel don't undermine each other causing them to fall through to the tile below. If this happens you may need to build a stair or a ramp in order for the fallen miner to escape.

For dwarves to move upwards and downwards between levels the construction of stairways and ramps is required. The most reliable way to assist your constructions is to dig an upward stairway on the lower level and downward stairway above. You can also construct these out of rocks or wood, but well placed dig commands are quicker. Digging downwards from the surface, first dig a j downward stairway. If you wait for this to be dug you will then see a visible block on the layer below where the stairway connects. In this tile dig an upward stairway. Your dwarves will now be able to access both levels using these stairs. It is advisable to build one of these before channeling in order for your dwarves to escape.

When digging upwards it may be convinient to build an i up/down stairway. This automatically creates a downward stairway on the floor above. This style creates an X symbol inplace of a < on the default tileset, but leaves a > symbol on the floor above.

Stairs and Ramps can be removed using the z remove up stairs/ramps command. Select this and mark the stairs/ramps to be dug out.

Ramps should be avoided until you need to provide access to caravans as dwarves on the upper level cannot perform actions such as dig, or build when standing on the ramp (imagine they are 'half way' up the ramp).

Dig Priority

Dwarves will currently choose a tile to mine at random (closer tiles being chosen over farther ones), but dwarves have a priority over which side they will mine out from, causing them to walk around unmined areas to reach these prefered sides.

In order from most prefered to least prefered:

West > East > North > South > NW > SW > NE > SE

Z-axis preferences untested, though it appears to me that dwarves prefer to dig out lower areas from a diagonally located area (i.e. not standing on the down stairs while digging out the up stairs directly below the down).

Map Structure

If you are still confused about tunnels, floors and ceilings created by the mine command then look at the following diagram:

TOP VIEWS:      SIDE VIEW:
  LAYER 3       FROM -> 
  ██████..-     5 ██████
  ██████..-     4 ██████
->██████..-     3 ██████__
  ██████..-     2 ████  
  ██████..-     1 █████████
  
  LAYER 2
  ████████.
  ████████.
->████.....
  ████████. 
  ████████.
  
Key:
█ Solid rock
. Floor, visible from this layer
- Empty space, with a floor below
_ Ceiling (undermined section)

The Top Views try to show how digging into the mountain (on Layer 2) leaves a ceiling (floor) on the layer above. This is represented on the Side View by a thin line. Try to think of the mountain as a series of boxes where with a thin lid ontop of each. At any place the box can be filled or empty, and the lid above be there or not there. For example, you can create a wall and build a floor ontop of it. (Building a wall creates a floor on the next level by default, but this doesn't stop you building another floor construction ontop of it!)

Revised theory: Imagine the 3D world as a grid of cubes. Each cube can have one of three states; Full, Empty, Floor.

• Each cube can only be in one of these states.
• If a tile is Full it is inaccessible, but the cube above can be walked on (if Empty or a Floor).
• If it is Empty, then it has no Floor and may be accessible.
• If a Floor is present, then the cube is accessible.
• Additionally, floor constructions can be built in an Empty or a Floor cube provided their is access from the side

--Markavian (Please discuss)