Create a new layer called “Land Clip”, filled with white above that, and set its blend mode to Lighten. You will have a white image. Now, with this layer selected, Open the levels dialog (Colors->Levels) and grab the white output slider, and drag it down. As this happens, the land will be revealed. Stop at a place you like, and click OK. Post4-1.png
Now using the Magic Wand Tool, (making sure Sample Merged is Checked and the Threshold is 0) click anywhere in the dark area. This will define your coast. If you want to adjust it, just undo the selection (ctrl-Z) and change the levels of the “Land Clip” layer. I wand back and tightened the coast a bit. Post4-2.png
Now Invert the selection (Select->Invert), create a new black layer called “Land Mask” and fill the selection with white. Now save the selection to a Channel (Select->Save to Channel) and rename the channel to “Land Mask”. This will be used a fit bit later. Post4-3.png
Now clear the selection (Select->None).
That technique (the Three-Layer-Sandwich of noise, shape and threshold clip layer, or TLS for short ) will be a basic technique that will be used over and over again, using different blending modes between the noise layer (to give some variegation to the surface) and the shape definition layer. It will be used to define forests and mountains, even clouds in the sky.
This is probably a good time to save. Always save your work as an .xcf file. That is the native GIMP format and will preserve all the image information, including layers, channels, etc. It is similar in that way to the Photoshop native .psd format.
Post 5: Detour - Then Let’s Begin (But I have No Idea!)
If you have no idea for a map, here are a couple of options to generate a more random map…Just use a noise layer (set to smaller size, but keep the detail) This will five a variety of island shapes. Or use a gradient fill for the original shape definition layer. Or blurry geometric shapes (circles, arcs) Each of these will give different results. Here are 4 examples (from top left, clockwise: 50%grey, linear gradient at an angle, radial gradient, arc shape, blurred) all made following the TLS technique: Post5-1.png
And blended with the noise layer and a clip layer (lighten) applied: Post5-2.png
You may now see some similarities in this technique to the “Creating Random Coastlines in GIMP” and “Creating Not-So Random Coastlines in GIMP” tutorials I had posted a while ago.
To make the ocean/water (and the base contour for the land as well) a two layer variant of the three layer sandwich will be used.
Copy the “Land Mask” Layer, and rename it “Sea Shape”. Apply a Gaussian Blur (Filter->Blue->Gaussian Blur) large enough to eliminate the absolute black and whites of the image. In this case, I used the same size as the image (500px). Post6-1.png
Create a new layer and call it “Sea Noise” Fill this with Clouds (Filters->Render->Clouds->Solid Noise) set to a low size (3) and detail of 15, reseeding the random number. Set the layer blend mode to mode to Overlay, then merge it down with the “Sea Shape” layer by right clicking on the layer and selecting “Merge Down”. Post6-2.png
Duplicate this layer and rename it “Sea”. Add a layer mask by right clicking on the “Sea” layer, and selecting “Add Layer Mask”. When the dialog opens, select “Channel” (By default it should have the “Land Mask” channel shown and check “Invert”. Click Add. Post6-3.png
Nothing much will appear to have happened, but there will be a mask next to the layer thumbnail:
Layer masks act like filters that let parts of the image “show though”. Areas where the mask is white will allow the layer to be visible. Areas where the mask is black will be transparent, and the various shades of grey will be varying degrees of transparency. Now right click on the “Sea” layer and select “Apply Layer Mask”. This will remove pieces of the layer based on what was showing through the layer mask. Here I have made all the other layers invisible to see the result:
Also, check out the histogram….that is where we start next.
Now we want to stretch out the colours in the “Sea” layer across the entire black to white range. With the sea layer selected, auto normalize the image (Colors->Auto->Normalize). The histogram will now have little gaps in it. As the greys have all been spread out. To fix this, select the non-transparent area (by clicking on the “Sea” layer and selecting “Alpha to Selection”. Invert the selection (Select->Invert) and fill the area with white. Remove the selection (Select->None) and apply a 20px Gaussian blur. Post7-1.png
Note the histogram is now filled in.
Now the next bit of magic. Set the foreground colour to the darkest water colour (water 5) by clicking on it in the Palette Editor (that we set up at the beginning), and set the background colour to the second lightest water color (water 5) by Ctrl-clicking on it. Post7-2.png
Now we will turn the B/W into colour, by clicking Color->Map->Gradient Map, and the water is almost (for now). Post7-3.png
Recently, I came up with a nice technique (in my opinion) to finish the shoreline water. Often people will stroke the shoreline with a light colour, or add a light blur. Here is a quick technique for making a unique look…
Create a new layer called “Seashore”, and fill it with the really light water colour (Water 1). Add a layer mask, using the “Land Mask” channel, and ensure “Invert” is unchecked.
(Any edits you do now will be on the mask shape, unless the layer thumbnail is clicked. The one you are editing will have a white box: Post7-4.png
Give the layer mask a 10 px Gaussian blur.
Now apply a displacement map (Filters->Map->Displace). Use an X displacement of 20, and a Y displacement of -20. For both, pick the “Land Noise” layer. Set the Displacement Mode to Cartesian and the Edge Behavior to Smear.
Repeat this, flipping the signs, so set X to -20 and Y to 20. This screen grab is after the first one. Post7-5.png
This will give a nice wispy, random looking water edge, once the land is put in place…
Now that the ocean is completed, the land can be build up. Create a cop of the “Sea Shape” layer and name it “Grass”. Create a layer mask using the “Land Mask”channel. Click on the layer icon so we now edit the layer, not the mask. Post8-1.png
Ctrl-Click on the dark green (Ditch) colour to make it the background and click on the light green (high ground) to make it the foreground colours, then Colour->Map->Gradient Map. Post8-2.png
This is bland, so lets spice it up a bit…create a new layer called Grass Texture, and fill it with clouds noise (Filters->Render->Clouds->Solid Noise), detail 15, size 3, and new seed.
Again, add a layer mask using the “Land Mask” channel, and set the blend mode of the layer to overlay. Post8-3.png
Looking better, but it could use some texture.
Create a new layer called “Grass Bump Map”. Fill it with rendered cloud noise again, this time setting the size and detail to the max, and selecting Turbulent. Post8-4.png
Hide this new layer (by clicking off the eye icon). Create a new layer called “Grass Bumps” and fill it with 50% grey. Set its layer mode to overlay. It will appear to be gone now. That is how overlay works. 50% grey doesn’t change the underlying image, while darker shades darken the image and lighter shades lighten the image.
Now apply a bump map to this “Grass Bumps” layer using Filters->Map->Bump Map. Post8-5.png
Lastly, apply the “Land Mask” channel as a layer mask like before.
After the bump map we now have this. You can adjust the opacity of the bump map to make it less noticeable if desired: Post9-1.png
This is OK, but it is a little two green for me. One option is to change the overall colour by adjusting the hue, and that would be that. Instead, we’ll add a dirt layer. This will be a combination of a filter generated mask layer, and hand painting the mask.
Create a new layer called “Dirt” and fill it with the “med dirt” colour. Add some noise (Filters->Noise->HSV Noise): Post9-2.png
Now bump map this layer on itself to give a bit of lighting texture: Post9-3.png
Duplicate the “Land Mask” layer, bring it up to the top of the layer stack. Post9-4.png
I have to say I just started using gimp and did what me and my friends thought was a pretty decent map...but I just have to say, "Whoa". This is freakin' saweet tutorial and I'm actually redoin' the map so I can make it the way I wanted to.
) will be a basic technique that will be used over and over again, using different blending modes between the noise layer (to give some variegation to the surface) and the shape definition layer. It will be used to define forests and mountains, even clouds in the sky.
Reply With Quote
Bookmarks