Hi all:
I was wondering if there is a model that includes GIS, sea currents, and wind to simulate ancient seafaring.
I want to see if I can apply it to my research and see an example, so I can check what information I need.
Best
Diana
I don’t know if there is a model that includes sea currents and wind. However, I feel that you could base your model on the Vector Fields model provided in the Models Library of the NetLogo program. The model shows how to develop and display vector fields.
Essentially, the wind and sea current are vector fields. So you could assign wind and sea current vectors for each patch and then ask the agent to move forward based on a given logic. For example, if it is just the dominant vector, then the agent (ship in this case) will move as per the dominant vector. On the other hand if you choose between vectors over time, the ship will chart a new course depending on whether it follows the wind or sea current at a given time.
I updated the Vector Fields model to include an additional vector with random values for both vectors to see if the navigation concept I mentioned above works. The outcome is shown below:
The turtle (ship) starts at the lower left corner. Initially it follows tje sea current (green arrow). After some time I switched to wind based navigation and it follows the wind vector (orange arrow). Note that wind is the dominant vector in this model. I switched to wind two times. You can see how the course changes over time. Below is a run that depends only on the sea current.:
You could use GIS to map the patches to a water body and assign wind and sea current vectors to patches based on latitude,longitude and time.
Hope this helps.
2 Likes
Hi Pradeesh. I tried to create the model, but it is not working.
Coiba.nlogox (43,5 KB)
Hi @Diacarco ,
It looks like you have a bunch of errors related to variable names. When a there is a widget on the interface such as current-heading, that creates a global variable. If you try to declare it again in the the code tab under globals you will get an error that “There is already a global variable called ENDURANCE-HOURS”. You also can’t make agent-owns variables that have the same name as a global. So, you will need to rename endurance-hours for boats (assuming they really need to each have their own). You also don’t need to give boats a heading since that is a built-in variable for all turttle breads. Have you gone through the NetLogo Tutorials?
Hello Diana,
As highlighted by @jzkelter I couldn’t run the model due to the errors. I am attaching the model I used to create the images of vector field based navigation I posted earlier. Note that this model is a modification of the original vector fields model available in the models library. Further, there may be errors in my model as I have not tested it after modification. Hope this helps.
Best,
Pradeesh
Vector Fields.nlogox (44.4 KB)