ALMaSS Goose Memory Map Class Documentation

Version 1.0

Created by:
Chris J. Topping
Department of Bioscience,
Aarhus University
Grenaavej 14
DK-8410 Roende
Denmark

21st January 2013

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Overview

1. Purpose

The goose memory map provides a means for recording the goose's experiences in terms of food resources known and threats experienced.

2. State variables and scales

• All memories are held in a GooseMemoryLocation construct comprising:
  1. m_x is the x-coordinate location.
  2. m_y is the y-cordinate location.
  3. m_polygonid is an reference number to the polygon at the memory location.
  4. m_foodresource is a variable describing the remembered food resouces.
  5. m_threat is a variable describing the remembered threat at the location.

• All memories are handled by GooseMemoryMap with the following attributes:
  1. m_memorylocations is the list of memory locations held.
  2. m_decayrate is the rate at which memories decay per day.
  3. m_infinitememorystop is a limit at which a memory is so small it is forgotten.
  4. m_distancepenalty is the per meter rate applied to scores as a distance penalty.
     

3. Process Overview and Scheduling

Each time a location is visited it is scored for both threats and food resources. This and its location form the individual memory. The memory will decay with time at a certain rate, defined by m_decayrate (see DecayAllMemory() ). This decay will occur daily until m_infinitememorystop is reached at which point the memory is forgotten and deleted. All memories are contained in a list m_memorylocations which can be consulted to determine the overall score for a location (its attractiveness) using GetFeedingScore() or its food resource using GetFoodRes() or threat level using GetThreat() . The best/optimal location currently known about can be found using GetBestFeedingScore() and the total threat level can also be queried using GetTotalThreats() , which can be used to determine if a migration stop location is too dangerous a place to stay.