How do I remove overlapping blur in tight spaces

[MrDig]

Hello anyone who reads this. I've started working with a friend on a board game and I've been tasked with making the map. I'm fairly new to cartography, so I've been trying to follow some of the tutorials on the forums. For this version of my map I've been using this tutorial. Below is what I've come up with.

Near_Final_Version_Smaller.png

If you look closely at the tighter regions at the edges of the map, the blur overlaps creating a darker black and removing the sense of depth from those regions. I was wondering if there is any way to make a blur that doesn't overlap like this.

[Midgardsormr]

Hmmm… the way the glow works doesn't really allow for a variable radius, but you might be able to fake something. I'm not a Gimp user, so I can't give detailed instructions (assuming you're using Gimp, since that's what the tutorial was written for). However, if I were working on this in Photoshop, I might do it like this:

Make a copy of the landmass and put it above the existing land layer.
Adjust the glow radius so that the troublesome areas are the way I'd like them to look.
Rasterize the layer.
Put a solid black mask on the copy to hide it all.
Using a very soft white brush, paint on the mask in those spots.

Hopefully the soft brush would make a pleasing transition between the wide glow and the narrow one. I'm not sure if that would look good or not. It might appear odd that the glow changes radius.

The reason for rasterizing the layer is because Photoshop will apply the glow to the edges of a mask, which would defeat using the mask to choose where the modified glow shows up. I don't know if the Gimp has the same behavior or not. I think there's a way to change that behavior in Photoshop, but I don't have it available to me at the moment, so I can't check.

[waldronate]

If it were me I'd calculate a distance field on the thing that I wanted and use the inverse of that as the alpha channel on the color that I wanted to overlay. In Photoshop, use the stroke layer style positioned outside or inside with a gradient fill in the shape burst style and an alpha gradient (whew!). I don't know how you'd go about doing that in The GIMP, though.

A distance field is that thing that people like to use to get concentric rings around the outside of landmasses (the distance from the boundary is an index into a gradient or 1D texture). I'm sure that there's a precise technical term that the GIMP folks like to use (like the shape burst term).