1. Introduction

1.1. Overview

EnviroGen is a utility program for REvoSim: an individual-based evolutionary model, using a simplified first-principles evolutionary model to simulate large populations incorporating space, over geological time. An integral part of REvoSim is its fitness algorithm, which is linked to an environment within the software, which is in the form of an RGB raster image. We recommend reading the paper below for full description of this:

Garwood, R.J., Spencer A.R.T. and Sutton, M.D., 2019. REvoSim: Organism-level simulation of macro- and microevolution. Palaeontology. https://doi.org/10.1111/pala.12420

REvoSim is designed for versatility, and many simulations will require a changing environment throughout the course of a run. These dynamic environments are loaded in the form of image stacks. EnviroGen provides two different mechanisms for generating these dynamic environments, with a large number of options allowing the environments to be tailored to specific questions. For example, environments can have a high degree of fragmentation of colours to study endimism, be primarily defined by gradients, or have a range of complexities. There are numerous convenience functions built in to the software to ease processing image stacks.

1.2. Variables

Each mode of environmental generation has its own tab in the Environmental Setting dock, which by default is shown on the right of the main window.


This has a number of tabs on the top: Dyn 1 and Dyn 2 are EnviroGen’s dynamic environments, noise allows the user to create a stack of noise images, Comb allows stacks to be combined, Col allows the creation of solid colour stacks, and Stack allows the creation of a stack from a single image. The first tab, out, has output settings.

1.3. Quick start

An image stack can be generated by hitting run on the top toolbar. This is stored by default on the desktop for all operating systems: images are placed within a folder titled EnviroGen_output, and are saved as .pngs to as a compromise between file size and lossless compression.


The toolbar has the following options:

Run:Generate environemtnal images.
Stop:Stop generating images.
Pause:Temporarily stop generating images.
About:Launch dialogue with information about EnviroGen.