40d:Exploratory mining

Exploratory mining is the process of mining large areas in order to obtain resources such as gems, metal ores and other types of rock. It is also used, to a lesser extent, to find the locations of hidden underground features such as chasms, underground rivers, magma and adamantine. The most straightforward method is to mark a large rectangular area for digging. Unfortunately, this method is also the least efficient. More efficient digging patterns involve digging out a smaller percentage of the stone in a given area, but still revealing a large percentage of the stone. These patterns are compromises, which depend on factors that will be described in this article. Note that exploratory digging is the process dedicated solely to discovery of resources and features. The digging process is usually separated, and not discussed here in great detail. The cheating counterpart to exploratory digging is the infamous reveal tool.

Factors in exploratory digging

These are the factors we shall consider for each digging pattern. Knowing them and deciding on their priority will help you find the most suitable pattern. Most of the factors are represented by numbers, obtained by dividing two quantities. Others are more subjective.

Labor

Labor is the amount of work that goes into the digging process. Exploratory digging is a work intensive process, capable of straining even a large fortress, but the work that goes into different patterns varies greatly. A fortress with a large supply of skilled miners can afford to consider labor low priority. The labor factor is the fraction of stone dug out of an area, and as such, it's a percentage, between 0 and 100%.

Scarcity

Scarcity Scarcity is the amount of desired material present in the rock layer. It's theoretically represented by the fraction of desired material in the soil layer, but one can seldom state it accurately or even estimate it. Scarcity is determined by the types of materials you're after. Single tiles are the scarcest, followed by small clusters, veins and large clusters. For the classification of your desired material, see the gem and stone articles. Undreground features are about as scarce as large clusters.

Visibility

Visibility Visibility is the amount of tiles that you reveal in the digging process. excavated tiles are always visible, and so are the tiles immadiately adjacent to them, including diagonals. The purpose of exploratory digging is to make a single tile of the desired material visible, allowing you to switch to conventional digging and extract it. Visibility is represented by the fraction of visible tiles in the excavated area. Visibility is always a priority, but it tends to decrease in priority as scarcity decreases, because there are more tiles that need to be dug out, and not just seen.

Reusability

Reusability Exploratory digging leaves behind a monotonous, repeating landscape. The excavated level may be hard to reuse for habitation, storage or industry without additional digging and significant rebuilding efforts that leave behind inferior walls that cannot be engraved. Reusability is subjective, and it depends on the desired layout. Reusability is represented by the largest room size achievable by digging into the solid rock left behind without rebuilding any walls. Reusability is a priority for a small fortress.

Patterns

Patterns are represented by a unit tile. This unit tile is repeated throughout the area intended for excavation to create the desired pattern. Each pattern is analyzed with the above factors in mind.

Hollow

Unit Tile:

X

Key:
X - Excavated tile

Labor: 100% of the tiles are excavated.
Scarcity: Any scarcity. It it exists in the layer, it will be found.
Visibility: 100% of the tiles are visible, obviously.
Reusability: Approaches zero. Any design other than a large hall requires reconstruction.
Bottom line: Hollowing wastes labor like there's no tomorrow, but integrates extraction into the exploratory digging process. Use only if you have a lot of labor to spare, really need huge amounts of stone and don't mind the reconstruction required to make the hollow area habitable.

Rows

Unit Tile:

OO
XX

Key:
X - Excavated tile
O - Tile left intact

Labor: 50% of the tiles are excavated.
Scarcity: Any scarcity. Clusters as small as a single tile are revealed.
Visibility: 100%.
Reusability: Very low. The long, thin corridors aren't very useful, and can only be expanded to long, wide corridors.
Bottom line: This method achieves the same visibility as hollowing out, but using half the labor. Ideal for hunting single-tile gems.

3X3 blocks

Unit Tile:

OOOX
OOOX
OOOX
XXXX

Key:
X - Excavated tile
O - Tile left intact

Labor: 7/16, or 43.75% of the tiles are excavated. Scarcity: Small clusters and up, as there is a single unexplored space in each unit tile.
Visibility: 15/16, or 93.57% of the tiles are visible.
Reusability: Low. small 1X1 rooms can easily be carved out of the stone, a fitting space for a commoner's tomb.
Bottom line: This method is slightly less labor intensive than a row-based design, at the expense of imperfect visibility. This method is ideal for hunting small clusters.

7X7 blocks

Unit Tile:

OOOOOOOX
OOOOOOOX
OOOOOOOX
OOOOOOOX
OOOOOOOX
OOOOOOOX
OOOOOOOX
XXXXXXXX

Key:
X - Excavated tile
O - Tile left intact

Labor: 15/64, or 23.4375% of the tiles are excavated.
Scarcity: Veins and up, as the large 5X5 space left in each unit tile can easily conceal a small cluster.
Visibility: 34/64, or 53.125% of the tiles are visible.
Reusability: Medium. The 7X7 blocks can easily be converted into 5X5 rooms, suitable for individual rooms, storage or workshops. Easily converted into the more thorough 3X3 block patten by digging through the large blocks.
Bottom line: This is a low-labor method great for vein-hunting. The low labor cost puts you in a position to invest more and get better covarage if desired.

15X15 blocks

Unit Tile:

Refer to the 7X7 pattern, and employ your imagination.

Labor: 31/256, or about 12.11% of the tiles are excavated.
Scarcity: Large clusters and up, as the large 13X13 space left in each unit tile can easily conceal quite a lot.
Visibility: 89/256, or about 34.77% of the tiles are visible.
Reusability: High. A 15X15 block of solid rock is extremely versatile when it comes to interior design. It's easily converted into a 7X7 block design, which may be further converted into a 3X3 block design.
Bottom line: This method is preferable when you are low or labor, or when you're after an underground feature. It can easily accommodate parts of your fort, or serve as the precursor for a more thorough search.