02-02-2019, 05:19 AM
There are various ways to do this, depending on the effect you want. One way is to use a light beam brush (sample attached). Unzip and place the .gbr in the brushes folder of your user profile.
C:/Users/YourName/AppData/Roaming/Gimp/2.10/brushes
Refresh the brushes or restart Gimp.
Create a new transparent layer above your map.
Set the foreground colour.
Select the light beam brush and set the brush size.
Paint on the transparent layer (a single click in the position you want).
Reduce the opacity of this layer (say to 50%).
There are many light beam brushes on the internet. Many are in photoshop .abr format that work in Gimp.
If you want a more uniform layer, create a new layer with the colour of your choice. Create a layer mask for this layer and apply a radial white-to-black gradient on the mask. This is similar to a vignette. The standard vignette will darken the outside portions of an image, you want to lighten the centre.
C:/Users/YourName/AppData/Roaming/Gimp/2.10/brushes
Refresh the brushes or restart Gimp.
Create a new transparent layer above your map.
Set the foreground colour.
Select the light beam brush and set the brush size.
Paint on the transparent layer (a single click in the position you want).
Reduce the opacity of this layer (say to 50%).
There are many light beam brushes on the internet. Many are in photoshop .abr format that work in Gimp.
If you want a more uniform layer, create a new layer with the colour of your choice. Create a layer mask for this layer and apply a radial white-to-black gradient on the mask. This is similar to a vignette. The standard vignette will darken the outside portions of an image, you want to lighten the centre.