A key to cartography within Photoshop is to be able to quickly resize, reshape, or move elements while maintaining fidelity. The best way to do this is to work entirely (or mostly) in vector shapes.
To start, you need to know the difference between pixel layers and vector layers (also called “shapes” and “paths”).
A pixel layer contains that: pixels. Each pixel on the layer can be its own color or opacity. Pixel layers are difficult to work with because they’re “rasterized” – effectively “permanent”. You can overwrite pixels with other pixels, and you can mutate the layers, but it warps the pixels. However, pixel layers are very useful in other ways (especially with large documents).
A vector layer contains what’s called a shape or a polygon or a path. Vector layers are described with math that describes the coordinates of each of its anchor points and the connections between them.
Consider a red square that is 30 pixels by 30 pixels and is located at 100,100 (x,y). On a pixel layer, all pixels in the area between the area are colored red with an opacity of 1 (or 100%). On a vector layer, the same thing is described in math (anchors at [100,100], [100,130], [130,130], and [130,100], with a color fill of “red”).
You can resize both layers! But you will likely get blurring with a pixel layer when you do so, whereas with a vector layer the points remain exact. Since map making (especially blueprints) often requires rapid manipulation of shapes, vectors are the choice here.
The number of people I meet who think that Photoshop doesn’t or can’t do vector shapes well is weirdly high. Over the years, Photoshop has become my go-to for shape work.
So how do you make them? It’s simple: you use the various Shape tools: the Rectangle, Rounded Rectangle, Ellipse, Polygon, Line, or Custom Shape tools.
- Add a new layer and select it.
- Go to your toolbar and select the Shape tool. It’s probably a circle or a square. There are several tools within: ellipse, rectangle, rounded rectangle, line, custom shape.
- Select the Rectangle tool.
- Click a point on the map, hold down the cursor, and pull in a direction. You’ll see the shape appear.
- Holding down the <shift> key will constrain the ratio of the shape (useful for making perfect circles).
Each shape tool has options (at the top bar) that you can modify. This is where you go to change the custom shape, for instance, or the border radius in a rounded rectangle. Don’t worry so much about fill and stroke right now.
Okay, now that you’ve got shapes, it’s time to talk about the Pen tool. The pen tool also has several types, but you really just want to think about the main pen tool right now. This draws straight lines between anchor points. The pen lays down anchor points, allowing you to create arbitrary shapes. Just click on the first anchor point you laid down to close the shape (the cursor will change to indicate that you’ll be making a connection).
There are other pen tools. They can add or delete anchor points or change how they work. The big one to know is the Convert Anchor Point tool. It turns an anchor from being a solid corner to being curved with what are called “Bezier Handles”. Moving the handles around changes the curve of the point. Curves take some practice to get right.
The Selection Tool
Just above the Shape tool is the Selection tool. It’s either a black arrow or a white arrow, depending. The black arrow is the Path Selection tool and it will select all points and connections for a shape that you touch with it. The white arrow is the Direct Selection tool and will select individual anchor points. This one is far more useful for what you will do.
When you select individual anchor points, you can move just that point on the map. Want to resize only one half of a room? Select all the points on one side and not the other and you can move them with the arrow keys (hold down the <shift> key to move things by 10 pixels at a time). Hold the mouse and drag to move them all at once. Hold <shift> while dragging to force the motion to be in a line.
Combining and Subtracting Shapes
When you have two shape layers, you will often want to combine them or subtract one from the other. For instance, when I draw a battlemap room, I’ll often draw the shape of the room’s floor first. Then I’ll duplicate that layer, increase it’s size, and then subtract the shape of the floor (a duplicate layer) to create the shape of the walls. Or if I want a room that’s rounded on one side and square on the other, I’ll make a big circle shape and then merge it with a rectangle shape that is the same width.
Combining shapes is easy.
- Select the shapes you wish to merge (<command><click> on each layer)
- Go Layer -> Combine Shapes -> Unite Shapes
Bam. Now they’re a single layer!
But you have one more thing you need to do: merge the shape components. If you don’t do this, you’ll get weird effects when if you merge with another shape layer. To do this, select any shape manipulation tool (Shape, Pen, or the Path/Direct selection tool) and then in the top bar there’s a menu with a square or two square on it; you want to select the last thing in the list (Merge Shape Components). This deletes extra lines and combines anchor points that have the same coordinates.
Subtracting shapes is just as easy.
- Make sure the smaller shape is on top of the stack
- Select both shapes(<command><click> on each layer)
- Go Layer -> Combine Shapes -> Subtract Front Shape
- Merge Shape Components
When shape layers merge they take the name, effects, and color of the “top” layer, always. I absolutely guarantee you that you’ll fuck this up a lot and have to undo work. You’ll forget to duplicate the layer you’re chopping, for instance, or you’ll lose some layer styles. It happens. You’ll get a rhythm eventually, though.
Say you have a shape for your walls, and you need to make a hole for an open doorway. There are a couple of ways to do this but the quickest is to add some anchor points along the shape and then delete some.
- Select the shape layer you wish to add a hole to.
- Use the Add Anchor Point tool to add three points on each side of the wall you intend to breach (total six).
- These points will have “curve” handles which you may not want, so then go over each of the six points with the Convert Anchor Point tool to turn them into corners.
- Switch to the Direct Selection tool (white arrow) and select the two middle points and hit the delete key. Pow, they’re gone! But your shape is no longer solid!
- Switch to the Pen tool. Click one of the points you added on one side of the wall and then click its opposite on the other side. Do this for the other two points, and you’ve regained the shape integrity.