[Award Winner] Drawing hand drawn maps in Gimp

[harchunk]

Considering I cant draw at all I think the ship is nice

[torstan]

Welcome over here Harchunk - another victim of RPMiller I guess.

[torstan]

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.

---Useful tangent---
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:

[torstan]

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:

[ravells]

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.

[torstan]

Multiply is also really useful if you want to use a reference drawing. So for example say you found a map on google of a region you wanted to turn into a hand drawn map. Copy that image to your computer. Open up your parchment image as above. Open up the Google image and scale it so it will fit nicely over your parchment layer. Create a new layer over your parchment layer and paste the Google image on to it:



This gives you something like this. Now change the Layer mode to multiply and you get something like this:



Now create a new transparent layer (remember shift-click), choose the ink tool and start tracing round the coastline, along roads and so on until you have a line drawing of the map you are after. This way you need never complain of lack of hand-drawing skills or inspiration again!

Now that we have got our ink lines by subterfuge, deceit or elbow grease, we'll move on to colouring the image tomorrow.

[torstan]

Okay, now that we have our lines, we need to get some colour down. In this case there are four different coloured areas - the sea, the deck, the sails and the rocks. First things first - create four new transparent layers and name them for the colours they will hold.

We'll start with the sea colours. We could just do a block fill of a nice sea colour to start with, but that's a bit dull. It's more interesting if we can get a bit of variation in the colour for the sea, so we will build it up bit by bit.

For varying colours I find it useful to use the airbrush with the 'Use colour from gradient' switch turned on. Gimp comes with a deep-sea gradient so that seemed particularly appropriate for this case but you can use others, or make your own. In this case I use the following settings:



Now take a large fuzzy brush and block in the sea with colour. Note that I have scaled up the brush to aid in quickly filling a large area. Don't worry if it's not smooth at this stage. We'll deal with that in a minute. Also, don't worry if the colours aren't quite right. They are just going to give us a starting point. Finally, the edges are also not a great problem. It is more important to get the colour up to the edges of the area you are filling in than worry about going over into the adjoining area.

The end result will look blotchy and non-too smooth. Switch from the airbrush tool to the smudge tool. Now I decided that I wanted it to look as if the waves were rolling in from the north-east. Therefore I use the smudge tool to blur the colours in lines from north-west to south-east. Here is a screenshot of the smoothing in progress. Note that the area in the bottom right of the image has not been smoothed yet.



Notice how the colour variation smooths out to give the impression of waves. Now this still looks a bit lurid. I'll deal with that next.

[RobA]

---Useful tangent---
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

I'd rep you for that if I could... never knew that one! Thanks

-Rob A>