Keeping it Natural
Some of the hardest parts of any model to make look right are the
sections where nature has left its mark. Weathering, erosion, vegetation
or other random effects, like the results of an explosion, seem to be
difficult to reproduce in a way that looks natural. There is a very good
reason why this is the case – it is your brain!
human brain has evolved to recognise patterns. Even when there are no
actual patterns visible, your brain tries to make them up. Don’t believe
me? I bet you have looked at staining on a wall, or a similar random
shape, and thought, “That looks just like a …” - and it gets worse.
Your brain is so good at detecting patterns, and putting names to them,
that you can view an infinite number of different objects of various
shapes, sizes and colours, and happily label them all as “a tree”. So,
you have seen millions of trees, you should be able to draw one,
shouldn’t you? Give it a go – get a sheet of paper and draw a tree from
memory. Provided you didn’t cheat, you have probably drawn a lollipop
shape, unless it is near Christmas, in which case you may have drawn a
triangle with a stem. Your brain is quite happy to accept this very
crude symbol as being a tree, even though it looks nothing much a real
one, and this is the crux of the problem – your brain is very bad at
making random arrangements – it tries to put patterns into everything.
Nature, by contrast, seems to work in a much more random fashion.
Although there are many genetic and environmental rules for how a plant
grows, the chaos effect ensures that no two will ever look exactly
alike. Different rules may apply, but most other natural processes work
along similar lines – erosion of rocks in a cliff face, veining in
marble, patches of lichen and moss, graining in timber. All these
“patterns” exhibit a form of chaotic behaviour which is governed by
rules so intricate, that the results appear to be more or less
There are a couple of ways to prevent your brain from creating
structures and patterns that look man-made. The first of these is to use
reference material: finding real-world examples of marble, trees, cliff
faces, ruins or whatever, and using these as a basis for your model. You
should be able to find plenty of suitable images on the internet for
this purpose, although taking your own pictures will give you a library
of your own high-resolution images to browse. For certain applications,
the best option will be to buy a book: aerial photographs of landscapes,
for example, would be difficult to take yourself.
images below are of a gravestone covered in different lichens and
mosses, and the model I created using the image as a reference.
second method is to use a procedure which randomises the results in some
way. There are different ways to go about this for different
applications. As a first example, consider that you are colouring the
blocks in a wall in slightly different shades to give a random
appearance, as in the image below.
To help with random
paint schemes for walls, floors and roofs, I have created a series of
online tools which generate
Some example output
images from the
However, instead of using a specific picture as a reference, you could
mix six slightly different shades of colour and number them. You could
then use a randomiser (six-sided die) to select the shade for each
block. This will give you truly random results, whereas if you choose
the colours you will be influenced by your brain’s liking for evenly
spread blocks of colour.
Another “random” effect can be achieved by stippling or sponging paint. This procedure is used heavily in my techniques for
creating marble and granite. Whilst you choose where to stipple to some
extent, the actual blobs of paint left are in a semi-random pattern,
which is perfect for these types of texture.
useful method for rubble, bushes and other "occasional" features, is to
drop it from a short way above the model, and glue it where it lands. If
using this technique for rubble, start with the largest blocks first,
let them set, and gradually progress through to the smallest pieces.
Sand can be added as a last step, and then sprayed with a 50/50 water/PVA
mixture to stick it into position.