# DBA terrain and camp sizes

## Terrain sizes

**Confused by terrain sizes?**

The DBA rules about terrain sizes are a little convoluted, so I thought a diagram might be useful. It is a plot of feature width (in base widths) against feature length (also in base widths).

All dimensions are in base widths (BW) unless stated otherwise.

**But please read "An important note about rectangles and diagonals" at the bottom of the page!**

**The coloured regions**

The key coloured regions are:

- Red: all but one (at most) terrain features must be in this region.
- Orange: only one feature can be in this region
- Yellow: this regions shows the permissible sizes of gullies.

**The lines**

The lines represent the limits, based on the conditions in the rules:

- L + W = 9: each must fit in a rectangle of which the length plus the width is less than or equal to 9 BW.
- L = 3: only one feature can have a length less than 3 BW.
- L = 1, W = 1: every feature must have both length and width of at leas t 1 BW.
- L = 3 W: a gully's length must be at least three times its width.
- L = 2 W: the length of non-gullies must not exceed twice their width
- L = W: length is greater than or equal to width

**The dots**

These represent the integer valued solutions. So, for example, a typical terrain feature (non-gully) will be in the red region. The red dots indicate the possible sizes that are integral numbers of BW wide and long. In this case, these are: 6 x 3, 5 x 4, 5 x 3, 4 x 4, 4 x 3, 4 x 2, 3 x 3, and 3 x 2.

**Some extreme values**

- Gullies
- Longest you can have is 8 x 1.
- Widest is 6.75 x 2.25 (it is also the largest area gully).
- Smallest is 3 x 1.
- Non-gullies
- The longest is 6 x 3.
- The shortest is 1 x 1.
- The largest area is 4.5 x 4.5.
- The smallest area is 1 x 1 (for one piece of terrain only) and 3 x 1.5 (for the other pieces).

## Camp sizes

Here is a corresponding image for camp sizes.

The key coloured regions is:

The lines represent the limits, based on the conditions in the rules:

These represent the integer valued solutions. 1 x 1, 2 x 1, 2 x 2, 3 x 1.

**The coloured regions**

The key coloured regions is:

- Red: camp dimensions must be in this region.

**The lines**

The lines represent the limits, based on the conditions in the rules:

- L + W = 4
- L = 1: must be at least 1 BW long
- W = 0.5: must be at least 0.5 BW wide.
- L = W: length is greater than or equal to width

**The dots**These represent the integer valued solutions. 1 x 1, 2 x 1, 2 x 2, 3 x 1.

**Some extreme values**

- Smallest area: 1 x 0.5
- Largest area: 2 x 2
- Longest: 3.5 x 0.5
- Shortest: 1 x 0.5
- Widest: 2 x 2

## An important note about rectangles and diagonals

DBA states that area-features "must fit into a rectangle of which the length plus the width totals no more than 9 BW."

The largest area area-feature you can therefore have is a 4.5 BW by 4.5 BW square.

What is the smallest area-feature you can have?

You would have thought a square feature that is 1 BW x 1 BW.

However this is incorrect!. Length is defined as "maximum dimension" and width as "maximum dimension at a right angle to its length".

So the smallest feature has diagonals of 1 BW. It is therefore a square whose sides are 1/SQRT(2) BW. If 1 BW = 40 mm this equates to 28.3 mm.

The largest area area-feature you can therefore have is a 4.5 BW by 4.5 BW square.

What is the smallest area-feature you can have?

You would have thought a square feature that is 1 BW x 1 BW.

However this is incorrect!. Length is defined as "maximum dimension" and width as "maximum dimension at a right angle to its length".

So the smallest feature has diagonals of 1 BW. It is therefore a square whose sides are 1/SQRT(2) BW. If 1 BW = 40 mm this equates to 28.3 mm.