How to convert a feGaussianBlur in SVG to a GaussianBlur effect in JavaFX?

Question

I am developing a library (fxsvgimage) which I use to show a SVG image in JavaFX. I am in the process of implementing the filters, and I have a question about the feGaussianBlur filter: Is it possible to convert reliably the stdDeviation parameter of the feGaussianBlur to the radius parameter of the GaussianBlur effect?

It seems that if I use the same value, I have a less blurry result in JavaFX than in SVG. For example, if I used this svg image:

<svg id="Layer_1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 156.364 147.239">
   <filter id="blur-shadow">
      <feGaussianBlur stdDeviation="3" />
   </filter>   
   <style>.st0{fill:#DEDEDE;} .st1{fill:#3E295E;} .st2{fill:#FFFFFF;} .st3{fill:#429946;} .st4{fill:#F5EB30;}</style>
   <g filter="url(#blur-shadow)">
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   </g>

</svg>

With a stdDeviation of 3, I have this in SVG:

And this in JavaFX by using the same value for the radius:

Answer 1

Try setting your radius to 2 * stdDeviation. That's what the relationship between the two generally is. Hopefully JavaFX also follows that rule.