torstan - I'm really looking forward to this, because hand-drawn maps are more my thing. Please continue with it.
After foolhardily promising to provide a tutorial for the style of my pirate cove map, and equally foolhardily implying I would pitch in for this month's contest, I have decided to kill two birds with one stone and do my May entry as a tutorial.
I have decided to draw a ship-wreck as my tactical encounter map. There seems to be a sea theme to the current challenges so I thought I'd shamelessly pander the the audience and continue the pirate theme. I also need a ship-wreck for my current game so it seems to work.
The first step in these maps is to get hold of a decent parchment background. There are many excellent tutorials on how to create such a thing from scratch and I will not go into this here. However, note that a lot of the colour of your map will come from this parchment colour, so make sure it has the tone you are looking for. If you are mapping for a dark game - Cthulhu being the obvious culprit - then dark tones, low saturation and the odd blood-stain are the order of the day. If you are mapping for a standard high-fantasy map then ramp up the saturation a bit, and lighten the parchment colours. The lighter the map, the more colourful it will be later on. If you find the colours are off later in the process, don't worry. We'll be keeping the parchment layer as the background so it can always be swapped out later to test different effects.
Make sure you have a parchment background of the correct size for your final map. Set this to be your background and create a new transparent layer. Name it sketch.
Now, I will be assuming the use of a tablet for this I am afraid. A mouse will also work, as will a scanned pen drawing - I'll add an aside on the pen drawing question a little later.
The first order of the day is to sketch a rough layout of the drawing. This will be the base for the careful pen drawing that will come next. At this point it is all about getting the composition right. I now (after RobA's excellent tip) use the ink tool. This is highlighted in the following image. I set the size to 2.5 (or thereabouts) and have the size sensitivity ramped all the way up. Now sketch (on the sketch layer) a rough design for the map. Don't worry about mistakes, this will never see the light of day. You'll use it as a base for later on. You should now have something that looks like this:
Note that this is not neat. It should be quick to draw and quick to correct. It should show all the major areas clearly and every main feature should be in roughly the correct position.
More coming. It's just that I ended up starting this while doing a two week tour from Poland back to the UK via Oxford for wedding prep and then to Barcelona (currently) for a physics conference. Real life has got a little in the way of more important matters! Not to worry, I have a whole day tomorrow of seminars so I'll have plenty of time to plot about plotting.
Now that the basic layout is there it is time to start inking in the final lines.
First reduce the opacity of the sketch so that you can use it as a guide, but you can tell what is being drawn now and what is the sketch.
Create a new layer and name it appropriately. I called mine DeckLines. This will hold the ink lines for one of the large objects in the image - in this case the ship's deck.
Now before you go any further, it is quite likely that you want to refine your sketch. In this case, create a new layer called sketch2 over the desaturated sketch layer and begin a more careful sketch. Here's the progression of sketches I used to get to my final boat layout for this image:
Each one was drawn on a new layer above the older one which was desaturated as shown. Once you have got a newer sketch then you can ditch the older one. The best way is just to hide the layer by clicking the eye that is beside it in the layers palette. You don't know when it will be worth going back to one of these older sketches.
When you are happy with your sketch, go to your ink layer, in this case called DeckLines, go back to the ink tool with your favourite setting and start carefully inking in the lines you want to have at the end. Don't be afraid to use ctrl-Z if you're a bit off. Also, make sure you are working at 100% zoom or above. Gimp can pixelate things if you work at lower zooms and what looks great at 50% doesn't always look good at 100%.
Also, don't worry about areas that are below another object. I drew in the deck without the fallen masts first and went back to create the broken areas later. It's easy to erase a small portion of the line drawing later and redraw it as necessary.
Don't be afraid to add new layers to start working on a separate object.
Here's the finished line-drawing for this ship. Here I have been a little sloppy and deleted the old sketch now that it is no longer needed. Notice that there are 4 line layers that contain the overall ship and deck lines, the textures on the ship's deck - the woodeon planking and the hatch over the hold - and similar breakdowns for the area beneath the water.
Considering I cant draw at all I think the ship is nice
An alternative way to get a line drawing into gimp is to scan a hand drawn map. For example here's the hand drawn map of Dragonford:
If you have a scan like this you can place it over your parchment in a number of ways.
First open the base image of a parchment background as above. Now open your scanned image in a separate window. Scale the scanned image so that its dimensions are within the size of the parchment image you will be using as your background. Select-all and copy the scanned image. Now go to your parchment image and create a new transparent layer.
Note that shift-clicking the new layer button in the layers dialogue creates a new layer with the last used values. This saves ages when creating lots of new layers like we will be doing here.
---end of tangent
Paste the copied image into this new layer. You will now have something that looks like this:
Now this is no use to anyone right now. We need to get rid of the white background. The easiest way to do this is to change the layer mode from normal to multiply.
This gives something that looks like this:
Note that there is a strange artefact around the edge of the old white image. This is there because the background wasn't as white as it looked. To get rid of this we need to mess with the levels. Make sure the layer with the scanned image is selected. Go to Color->Levels. There is a histogram under which there is a black triangle (far left), a grey triangle (middle) and a white triangle (far right). If your histogram looks anything like mine then there should be a large peak in the histogram at the right hand side. This is just saying that most of the image is white - not surprising for a scanned image on white paper. The width of this peak shows that there is a spread of 'whites' away from the true white marked by the white triangle. This is what causes the artefacts seen above. Slide the white triangle to the left of this large peak. Now every region that was just off-white will be pure white. Your artefacts should have disappeared, leaving you with an image something like this:
The second way to do this is as follows.
Follow the same process as before so that you have a pasted layer with a white background above your parchment layer. However don't set the layer mode to multiply.
Before going further, use the layers dialogue to correct the whites as described above. Now we are ready to move on.
With the scanned image selected go to Layer->Transparency->Color to alpha...
Make sure that the box beside "From:" is white. This will turn all instances of white on this layer into a transparent image. Now you see why we needed to have the background as pure white as we could. Press okay and you will see your white background magically disappear. I prefer this to the multiply method because you aren't affecting any other layers with this. Multiply does affect the layers below it so it can create some wierd glitches further down the line. Plus it will be useful to be able to mess with the line layer modes later on which we can't do if we are relying on them being set to multiply at this stage.
This should give you an image much as before:
Now this is a little light so we'd like to make it a bit darker. With the scanned layer selected press ctrl-shift-D or go to Layer->Duplicate Layer. This should darken the lines nicely. Play with the opacity of the new layer (using the opacity slider in the Layers Dialogue) until you decide it is dark enough. Then right click on the duplicated layer and go to Merge Layer Down. This gives you a lines layer as before. This now looks something like this:
Thanks Torstan, this is really useful stuff. I hadn't appreciated the downside to using the multiply approach to the alpha approach. I think I'll stick to the alpha approach from now on.