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This article will demonstrate how I created an ecosystem simulation in Houdini.

It�s really hard to say what makes us define something as beautiful or natural. However, generalizing aesthetical preferences of the majority of people we are able to say that this aesthetics is close to some mathematical relation discovered by Leonardo Fibonacci. He discovered it while examining speed of rabbits� reproduction. If we have a closer look at this relation, it occurs that phenomena based on it are far more attractive for humans� senses. If we divide any number from Fibonacci sequence by a preceding number, we get a quotient around 1.61804, which is the golden ratio, known as early as in ancient times. How is that possible that the ancient architects knew this? Probably nature in the evolution process taught us the way we define beauty. We are not able to explain our choice�s rightness because we favour it subconsciously. Leonardo Da Vinci was correct to notice that the relation between the navel�s position on a human�s body and the height of the body is close to 0.618. This can be seen on his sketches. In addition, most of Mozart�s sonatas were divided into two parts precisely according to the golden ratio. Contemporary musicians making minimal music (Steve Reich, Terry Riley, and Philip Glass) intentionally use Fibonacci sequence. What you will see in the following is purely mathematical, but at the same time, it is a bit unpredictable. You might say there is magic in it, just as there is in the PI number.




The target of the project was to create procedural plants model, which sent themselves information and form in such a way so that in the result they make one organism. This organism is an ecosystem in which every plant, every leaf and fruit has its own not incidental place. The project takes into account basic subjects of ecology, visual analysis of ecosystems, Fibonacci sequence and collision patterns from phyllotaxis family.


The seeds simulation has influence on the whole ecosystem. Can say that it's very event because seeds don't have any influence on what circumstances there are on the ground they are put on. Picture below shows an example of such simulation:


The most important task of every seed is to take the highest place for the future plant. If two seeds are close to each other and the area taken by them spreads fast then they fight for their place and the one that gained more energy for life wins. It's also possible to push the enemy away, but it happens rarely when the energies of the seeds are similar and not enough to win with the enemy. In that case, it comes to a division of the zone by collisions.The seeds accumulate the value of the Vigor that is a result of the comparison of the supplies that they have, with the settings in the window which controlls those simulations:


In the bookmark Calculate Vigor we set what decides about plants� growth speed. If water has big influence, only those seeds that have enough access will grow good. Water Intensity favours only those seeds with the optimal amount of water. Option Constant Intensity makes all seeds� growth faster at the same time, what makes them thinning. In other words, plants begin to gain more place and compete with themselves killing each other:


From the previous simulation we know how much space seeds take and what life conditions they have. Assume that seeds have sprouted and there appeared little plants. A necessary factor is the photosynthesis, which is calculated from the average access to the sun in a day cycle. Here is the tool for this simulation:



Let me mention only the most important options: "sun sample" describes how often a plant�s access to the light must be checked. For example, if sun shines for 15 hours within a day and we would like to do measurement every 10 minutes we must set that value to 90(15h*60m/10m). Turning on "Disable Set Vigor" we give our plants second chance, where "Vigor" sets "Constant Vigor". In section "Grow Setup" we describe what influences the daily plants� growth. �Phottosynthates Total Step� describes how may of the virtual days simulation should last. All those possibilities of settings are made with visual effects in mind and there is a possibility to break previous dependency (seeds simulation) what enlarges the influence of the user on the final effect.

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