I had a bit of a play while I figured out how I was actually going to do the illustration. I learnt that I needed to be on the ball and plan it well from the start because any mistake I made early on would be magnified as the project went on.
The area crosses two maps and I defined what I was going to cover in the illustration. I magnified the maps 200% when tracing the contour lines. For each A3 sheet I traced the 50m/100m/150m lines first and went over them in pen, filling in the rest of them with pencil afterwards. This helped make it more manageable and meant I could keep track of what their values were quite late into the project. The lines were easier to trace through rural areas than built up areas.
I didn't actually trace them all before I started painting. I was finding it really difficult to keep track of the lines, especially through built up areas. I started painting to turn the all the lines into shapes instead, because the shapes work a lot differently and behave differently with each other, so it was easier to see what was going on and make them more difficult connections.
I learnt a lot about mixing paint precisely while doing this illustration - I only used lemon yellow, cadmium yellow, cadmium red, ultramarine (blue) and I might have used a bit of crimson red? To get the rest of the colours. I learnt a lot about how the amount of layers alter the colour, and how many layers are needed to completely hide what lies underneath! Consistency in my approach was really important for this illustration, so when I bought more paint and the woman in the shop told me about the extra thick super pigment whatever version of the paint I was currently using, it sounded interesting for future reference but I didn't want to confuse myself by applying it halfway through this illustration.
It's done what I wanted it to do for now, but I'd like to do a lot more work to it. It's very time consuming because of the size. I'm torn between cutting it up into smaller squares or finishing it as one massive painting.