Foundry VTT Walls and Lighting: Turning a Map Image into a Playable Scene

A battle map image answers “what does this place look like?” A Foundry scene must also answer “where can the token move, what can it see, what can the light reach and which doors can open?” The difference between those two products is the preparation layer.

Foundry's walls and lighting system is powerful because it is explicit. A wall can block movement, vision, light or sound. A door can open. A secret door can look like a normal wall to players. Lighting and token vision then turn those boundaries into the information a player receives.

The scene preparation table

Layer	What it controls	Minimum question	Typical error
Map image	Visual appearance	Does the grid and scale match the scene?	Beautiful image imported one square off
Normal walls	Movement, vision, light and sound	Where are the solid boundaries?	Tracing decorative art instead of playable geometry
Doors	Openable boundaries	Which passage changes during play?	Making every doorway a permanent wall
Secret doors	Hidden interactive passage	What should the GM control before discovery?	Using a visible door icon that reveals the secret
Lights	Illumination and atmosphere	What does a token actually see?	Adding bright lights without checking wall leakage
Token vision	Player perception	Does the token have the right range and mode?	Testing with a GM token that bypasses the player experience

What walls actually do

Foundry's official Walls article defines walls as boundaries that can restrict token movement, line of sight and sound. The default wall is not the only option. Terrain walls, invisible walls, ethereal walls, doors, secret doors and window walls each express a different gameplay rule.

Use normal walls for a solid boundary. Use a door when the passage has a state. Use a secret door when the interaction should not be obvious to players. Use an invisible wall for an invisible gameplay boundary, not as a shortcut for a wall that was hard to trace. Use a terrain wall when you want the obstacle to affect movement while allowing some perception through it.

Lighting is not decoration

Foundry's Lighting documentation explains how light sources and darkness interact with walls and fog of war. A bright-looking map can still be dark to a player token if the scene requires token vision and no valid light reaches it. Conversely, a wall error can make a supposedly hidden corridor visible from the other side.

Test lighting from a player token, not from the GM's omniscient view. Place one token in the most restrictive room, one near a door and one outside the scene. Check what each sees after walls and lights are finalized.

A 15-minute preparation workflow

1. Minute 0 to 2: Create the scene, set the background image and confirm the grid dimensions in squares and pixels.
2. Minute 2 to 7: Draw the large structural walls first. Use the center of the graphical wall instead of tracing every texture edge.
3. Minute 7 to 9: Convert passages into doors or secret doors where the encounter needs a state change.
4. Minute 9 to 12: Add the minimum light sources needed for the intended mood. Avoid lighting every decorative lamp before testing vision.
5. Minute 12 to 14: Place a test token and inspect line of sight from rooms, corridors and thresholds.
6. Minute 14 to 15: Walk the scene as a player and keep a static fallback image if the map is heavy.

Where maps usually leak

Most light leaks are not mysterious engine bugs. They come from gaps, walls drawn on the wrong side of a doorway, accidental diagonal segments or tracing the outer edge of a thick illustrated wall instead of its playable center. Foundry's content creation guide recommends using the sub-grid and placing walls approximately at the center of graphical walls for better alignment.

What a prepared pack should include

Deliverable	Useful to the GM	Still needs a decision
Grid-aligned map	Fast scene creation	Scene dimensions and background scaling
Wall layer	Less manual tracing	Whether a decorative boundary is playable
Door states	Interactive entrances	Permissions and locked state
Lighting setup	Immediate atmosphere and vision	Token vision mode and encounter darkness
Fallback flat image	Resilience for slow clients	When to use it during the session

Sprixen's battle map workflow can help create a visual starting point and matching props, but a generated PNG is not automatically a Foundry scene. Treat walls, lights, permissions and player-view testing as part of the product. That is what turns a nice map into a reliable session tool.