Foundry VTT Setup Guide

You found the perfect dungeon map. The art is stunning, the room layout is exactly what your encounter needs, and the file came in at 4K with a gridless variant for VTT use. You drag it into Foundry, place it as a scene background, and then spend twenty minutes trying to figure out why the grid is off by half a square and all your tokens look wrong. This is the experience that sends DMs back to Roll20.

Foundry VTT is genuinely the best platform for running high-quality battle maps. Dynamic lighting, layered tiles, module support, and a self-hosted architecture that does not cap your file sizes make it the clear choice for DMs who care about production quality. But the learning curve on scene setup is real. This guide closes that gap: here is exactly how to import, configure, and run a battle map in Foundry from start to a polished, ready-to-play scene.

Why Does Foundry VTT Handle Battle Maps Better Than Other Platforms?

The practical advantages come down to three things: file size limits, dynamic lighting, and the tile system. Roll20 has historically capped upload sizes and resolution in ways that force DMs to downscale their maps. Owlbear Rodeo is excellent for quick sessions but is built for simplicity, not for a full dynamic lighting dungeon with fog of war and audio ambience. Foundry has no upload cap (you are self-hosting or using a hosting service), and its lighting engine is specifically designed for the kind of detailed dungeon and wilderness maps that serious DMs want to use.

The tile system is the other major advantage. Instead of a single background image, Foundry lets you layer multiple tile images: the base map, an overlay for a secret passage that reveals when triggered, weather effects, or a separate image for when the room is on fire. For DMs building reusable encounter scenes, this flexibility is significant. A single dungeon room can have multiple states without rebuilding the scene from scratch.

How Do You Import a Battle Map into Foundry VTT?

The import process is straightforward once you understand where Foundry stores files and how the scene configuration works. Here is the complete sequence:

Step 1: Upload the Map File

Open the File Picker in Foundry (the folder icon in the sidebar). Navigate to your maps folder (create a dedicated folder if you do not have one). Upload your map file. For battle maps, use the highest resolution version you have, which is typically the gridless variant. Foundry handles large files well, and starting with lower resolution to save time is a mistake you will regret when players zoom in.

Step 2: Create a New Scene

In the Scenes sidebar, click Create Scene. In the scene configuration dialog, set the Background Image by browsing to your uploaded map file. Before you close this dialog, you have a critical configuration to complete: the grid settings.

Step 3: Set Grid Scale Correctly

This is where most DMs go wrong. The Grid Size field in Foundry represents how many pixels correspond to one grid square. If your map is 4096 pixels wide and represents a 30-square-wide room, each square is 136.5 pixels. Set the Grid Size to 136 or 137. Do not guess. Check your map file's documentation or spec sheet, or use Foundry's grid calibration tool to align the grid visually after the fact.

Set Grid Distance to 5 (feet per square for D&D 5e). Set Grid Units to ft. These settings drive the distance measurement tool, which your players will use during play.

How Does Dynamic Lighting Work With Battle Maps in Foundry?

Dynamic lighting is Foundry's most powerful feature for dungeon and building maps, and also the most time-consuming to set up correctly. The principle is simple: you draw wall segments along the boundaries of your map, and Foundry's lighting engine uses those walls to calculate what each token can see. Players only see the illuminated area around their tokens. The fog of war fills the rest.

To set up walls, open the Walls Layer (the brick wall icon in the left sidebar). Use the Draw Wall tool to click along each wall segment on your map. For dungeon maps, trace every interior wall, every doorway (using the Door tool for interactive doors), and every opaque object that should block sight lines. Exterior walls that define the boundary of the playable space also need to be traced.

This takes time on complex maps. A typical 20x30 dungeon room with several interior features takes fifteen to thirty minutes to wall properly. There are two ways to speed this up. The Monk's Wall Enhancement module adds quality-of-life tools for wall drawing. Some professional map packs are now shipping with pre-drawn wall data that you can import directly into Foundry, eliminating the manual work entirely. When buying maps for Foundry use, check whether the pack includes wall data.

What Resolution and Format Should Your Battle Maps Be for Foundry?

Foundry can handle any image format, but WEBP and JPEG perform best in terms of load time without significant quality loss at typical viewing distances. PNG is fine but produces larger files that can slow initial scene load for remote players. If your map pack ships in PNG format, Foundry's built-in image converter or a quick run through an image tool before upload will help performance without sacrificing quality.

For resolution, the rule is: higher is better up to a point. At 4K (3840x2160 for a landscape map), you have plenty of resolution for any zoom level a player would reasonably use. Going above 4K does not meaningfully improve the visual experience at the table but does increase load times, especially for remote players on slower connections. 4K is the practical ceiling for most use cases.

The gridless version is almost always the right choice for Foundry. Baking the grid into the image limits your ability to adjust the scale after the fact, and Foundry's own grid overlay will look cleaner and more consistent than an image-baked grid at every zoom level. Only use the gridded version if you are exporting the scene for a platform that cannot overlay its own grid.

Which Foundry Modules Make Battle Maps Better?

The module ecosystem is one of Foundry's greatest strengths. Several modules specifically improve the battle map experience without introducing instability or compatibility risk:

Levels is the most significant. It adds true three-dimensional layering, so a multi-story building map or a cavern with a high ledge can have tokens at different elevations with correct sight-blocking between layers. For any map with elevation as a feature, Levels is effectively mandatory.

Monk's Wall Enhancement makes wall drawing faster and more precise. It adds snapping, better fill tools, and the ability to draw walls along straight lines more easily. If you are setting up dynamic lighting on a detailed dungeon map, this module pays for itself in time saved within the first session.

FXMaster adds environmental particle effects: rain, snow, fog, embers. These work as overlays on any battle map and can transform a static dungeon scene into something atmospheric without any additional art assets. Use them sparingly or they become distracting.

Sequencer is the module for animated spell effects and triggered visual events. If you want fire spreading across a battle map tile or an explosion animation on a specific square, Sequencer is how you do it.

Why Do Foundry Scenes So Often Look Wrong Out of the Box?

The most common issue is grid misalignment: the scene's grid does not match the map art's implied grid. This usually means tokens sit on the wrong squares, or worse, on the border between two squares. The fix is in the scene configuration. Use the Grid Configuration tool (the wrench icon in the grid settings) to visually calibrate the grid by clicking two known corner squares on the map. Foundry will calculate the correct pixel-per-square value automatically.

The second common issue is scene padding. By default, Foundry adds padding around the scene background to give players room to pan. For battle maps where you want the playable area to fill the scene, set Scene Padding to 0 in the scene configuration.

The third is fog of war performance on complex maps. If dynamic lighting is causing frame rate issues for players, the most likely culprit is too many light sources or a very high polygon count on the walls. Simplify wall geometry on complex maps (you do not need to trace every single stone, just the major boundaries) and limit active light sources to those that are narratively significant.

Foundry rewards the DMs who invest setup time before the session. The players who experience the polished version never see the configuration work. That is the point.

How Do You Know Your Foundry Scene Setup Is Actually Working?

Run a pre-session check on every new scene. Use a test token (your own GM token set to player visibility) to verify sight lines in every room. Doors should block sight until opened. Walls should not have gaps that players can see through accidentally. The fog of war should be clearing correctly as the token moves.

Check the grid calibration by measuring a known distance: drag a ruler tool across a space you know is exactly five feet wide (one grid square). If the measurement reads 5 ft, the grid is calibrated correctly. If it reads 3.7 ft or some other incorrect value, the pixels-per-square setting is off.

Finally, log into your own game as a player-level account to see what your players will see. The GM view in Foundry shows everything; the player view only shows what their tokens can see and what has been revealed. There is no substitute for checking the player perspective directly before the session starts.

Frequently Asked Questions

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