FRAGSTATS is a stand-alone program written in Microsoft Visual C++ for use in the Windows operating environment. FRAGSTATS was developed and tested on the Windows 7 operating systems, although it should run under all Windows operating systems. Note, FRAGSTATS is highly platform dependent, as it was developed in the Microscroft environment, so portability to other platforms is not easily accomplished. FRAGSTATS is a compute-intensive program; its performance is dependent on both processor speed and computer memory (RAM). Ultimately, the ability to process an image is dependent on the availability of sufficient memory, and the speed of processing that image is dependent on processor speed.

Of particular note is the memory constraint. FRAGSTATS loads the input grid into memory and then computes all requested calculations. Thus, you must have sufficient memory to load the grid and then enough leftover for processing and other operating system needs. To determine whether you have sufficient memory to process a particular grid, you can use the following formula: #cells*4bytes. Thus, if you have a 256 rows by 256 columns grid, the memory requirement is 256 kb (256*256*4/1024 bytes/kb). The memory requirement is not particularly constraining in a standard analysis, unless you are working with huge images on an older computer. The solution to this problem if it arises - unfortunately - is to get a new machine with as much memory as possible. An alternative solution is to break up the landscape into several smaller landscapes and analyze each separately. Indeed, in most applications, landscapes that are too large to fit in memory are more than likely too large to be meaningful landscapes for purposes of analyzing landscape patterns (see the Background document for a discussion of defining meaningful landscapes).

The memory requirement, however, is very constraining in the moving window analysis because FRAGSTATS requires enough memory for the input grid plus one output grid, plus enough leftover for other processing needs and system needs. If the moving window analysis is selected, FRAGSTATS checks to see if it can allocate enough memory for three grids (i.e., 1 input grid + 1 output grid + enough leftover to insure performance). In the above example, you would need at least 768 kb of memory to conduct a moving window analysis. Not too terribly constraining for most computers when analyzing relatively small landscapes. However, consider a 10,000x10,000 input grid; to conduct a moving window analysis you would need 1.14 Gb of RAM.