I have two different datasets: 1) seal occurence (point data) 2) fishing boat tracks (line data)

First, I need to create two density maps, i.e. one for each dataset. For the seal map, I want each cell on my output raster to be assigned a value 0-1 according to the probability of occurence of seals in this cell. I tried Kernel Density but it didn't give me probabilities. Any idea of what I should do?? For the fishing effort map, it is exactly the same question.

Second, as soon as I manage to create my probability map for seal data, I will need to test for the overlap between fishing effort and probability of seal occurence. To do this, I need each cell of my output raster to be given a value based on the following equation:


with the values in the denominator being the sum of all the cells accross my study area,i.e. all cells of the raster.

1 Answer 1


Before you address the second part of the question, which will likely be solved using raster algebra or a similar function, you will need to clarify in statistical terms what you mean by "probability of occurrence".

The "Kernel Density" tool gives you a raster where the cell values represent the "number of seals per unit area". In other words, how many seals are likely to be within the cell based on your input data.

Look at this page for more on density tools: https://www.esri.com/arcgis-blog/products/product/analytics/how-should-i-interpret-the-output-of-density-tools/

And look at this process in R for other options on how to rasterize your data: https://mgimond.github.io/Spatial/point-pattern-analysis-in-r.html

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