Digital mapmaking

A map I made during the map it wrong challenge

This post is an introduction for the mapmaking software summary post that will be published afterwards.

Before starting to map, it’s necessary to cover some basic things regarding manipulating images with software.

Using layers, more is better

Most people have a basic image manipulation software on their computer. Windows users call it Paint. The biggest problem is that Paint quickly reaches the limit of its potential because it can only have 1 layer. Using multiple layers is a big advantage. It means every element can be on a separate one. For example, if you are drawing a map; the coastline is on one layer, the colour of the ocean is on another and the colour of the land is on the third one. If you need to modify the colour of the ocean, you can do it safely without risking affecting the other layers.

With Paint, a small modification means you will need to redraw other elements as well because everything is on the same layer. It is like real painting, it can be unforgiving if you make a mistake. Multiple layers give you more freedom and you can stack/combine different effects. You can also make layers invisible without deleting them and turn them back on when you need them.

Two examples using layers

Mapping a forest. On the first layer, I start by drawing black lines showing the canopy and the general shapes of the tree. Then I add another layer underneath for the colours. I put it there so it does not hide the lines. I fill the forest with green. Lastly, I add a last layer that I put between the two. It will add colour variations to the forest. I set the layer as a clipping mask. The clipping mask is clipped at the layer just beneath it, the green one. I can modify the green layer without actually changing it or risking of exceeding the existing forest.

Layer mask: It creates another layer right next to the one you’re using. It allows to hide one layer partially or totally without affecting the main layer. It’s a black and white layer. White will show the layer at 100% opacity, while black will show it at 0%. The shades of grey have varying level of opacity.

Example: Close to the planet, it’s impossible to see the stars but they become gradually brighter by looking away from the planet. The first image show the map without the mask layer (you can see all the stars) and the second one has the mask applied (stars are partially hidden). As you can see, you can also apply or hide the mask at any time.

Keep as many layers as possible; do not collapse them

I’ve heard of professional photographers doing this: They take a picture in JPEG, make modifications in a program with multiple layers and then they compress all the layers back into a single JPEG. This is awful.

You need to keep as many layers as possible at all times. You might want to keep a layer so you can continue working on it later. You can also use it as a reminder of how you did something. Delete or compress a layer only when you’re sure you won’t need it again.

Also, be aware when you save in JPEG, PNG, or other non-native formats, there is always some loss of quality. You need to keep the original file and only use a format like JPEG for sharing the images with others. That brings me to my next point.

File types

The file types used for saving the file and for sharing with others are different.

If you have multiple layers, use the default file type of the program you are using. Each has their own extension. For example, it’s XCF for The Gimp, PSD for Photoshop and AI for Illustrator. Use these and keep that copy safe; that’s your main file.

Don’t use the originals to share your work, unless you really need to. First, most people won’t be able to read them. Second, they contain every layer and could reveal your tricks. It’s like revealing the ingredients of the KFC recipe. You can do it but most pro artist won’t do it unless the client is ready to pay for it. If you want to share, use formats like JPEG, PNG or GIF. Professionals deliberately reduce the quality of their work before sharing or insert watermarks to prevent theft. If you just want to share with friends, you don’t need to worry about all this.

The following file extensions are the most widely used to share pictures. You can always use other formats like SVG or TIFF; I’m just covering the basics:

• JPEG: Ideal when you have gradients, textures and a lot of colours, tend to lose more quality than PNG when saving but most software lets you adjust the level of compression. A little more compression can result in a drastic reduction in size with barely any noticeable differences. This is your all-around format for sharing.
• PNG : Supports transparency, good for small to large but simple images, manages gradients and textures but makes the size of the file explode; the loss in quality is marginal. Ideal for sharing vector-based images and keeping the size low without affecting quality.
• BMP : It is very similar to JPEG but doesn’t compress the image at all. The quality is only marginally better but the total lack of compression can result in much larger files. It could as much as 5 to 10 times larger. Use JPEG unless you need top-notch quality.
• PDF is not commonly used but has some advantages. It can support pretty much anything. It can be read by every computer. It can save layers and their parameters. It can be used as an alternative for the native file extensions such as AI and PSD. You can put everything on just one layer to make the file smaller but then PDF becomes the same thing as PNG or JPEG. The main disadvantage of PDF is that it needs to be downloaded in order to be visualized. Some sites can display PDF like a normal image file but it’s not common.
• GIF: Supports transparency, allows only a limited amount of colours, and supports animations. It looks horrible with gradients and textures. Ideal for sharing pictures while keeping the size small at the cost of quality. Basically, if you are doing a map, never use a GIF.

Dots per inch (dpi)

If you don’t intend to print your map, you can skip this.

Higher dpi means more dots in the same area, or more pixels. It is the resolution of your image. It only matters when you print or if you try to incorporate different elements together. Different elements at different dpi will have different size.

Example: you have 2 elements; one at 30 dpi and the other at 72 dpi. You can see here the difference between different resolution if they were printed on paper at the same size. The 72 dpi logo has more pixels per inch:

If you do the math right, you can adjust the dpi of the file at any time, so there is no need to worry too much about it. If you are using vectors, you can scale them at any size you want. Therefore, you choose the dpi only when you are ready to print.

Printable colours

I know this is valid only if you intend to print your image but if you pick bad colours right from the beginning, it could be very hard to modify them later if you change your mind. My tip would be to get used working only with colours the software identifies as printable. That still leaves millions of colours available.

This is Photoshop warning you with the triangle that the colour cannot be printed:

There is an option where you can ask to grey out all unprintable colours.

The non-printable colours are usually those that are very bright and very saturated (pure). Looking again at the pictures above, they are located in the top right part of the square. These are the flashy, neon lights, pop-art colours. Well actually yes they can be printed but not with a standard printer. I won’t go too much into details but these colours are called pantone. You use them if you only have a few colours to print and if you print in large quantities.

Colours: printer vs screen

(mostly just for your information)

There are 2 colour modes, RGB and CMYK.

Your screen use the RGB mode for red, green, blue but printers use CMYK for cyan, magenta, yellow, and black. CMYK colour spectrum is more limited but still allows plenty. It is not possible to print in RGB so every image will have to go through a conversion to CMYK. If you use printable colours, the difference is usually barely noticeable. CMYK colours usually look a bit dimmer.

That said, it’s recommended to work in RGB as many settings are disabled in CMYK and many software programs won’t let you choose between the two at all.

Also, your screen parameters as well as the colour settings of the software used will have some impact on the results. If you are not a professional graphics designer, you don’t need to bother about this.

In my next article, I will make a review of different software for making maps. I’ll explain the general categories. It will be followed by a brief description of each software.