Exporting to Foundry VTT

The Universal VTT export packs your map into one .dd2vtt file: the map image, the size of a hex in pixels, and walls. Foundry reads it through a free module, and one setting, the grid type, has to be set by hand, because the file format has no field for it.

Before you export

Walls come only from edges you have blocked with the Edge tool (G): click or tap a hex edge to block it, and again to clear it. Terrain does not become walls, not even terrain that blocks sight in Hexer, such as Solid Rock. Doors and light sources are not exported.

The export covers one layer, the one you are working on, and the level chosen in the dialog’s Scale Level menu, which starts on the base level. On a detail level, the edges you blocked on the base map are exported as walls too, so a wall drawn at the coarse scale still stops sight at the fine one.

What the image contains

The image is the player view without fog: DM-only notes and secret point-crawl locations are left out, and fog is not drawn, because Foundry handles fog itself. The grid, paths, regions and edges are always drawn. On the free plan the image carries a small “Made with Hexer” mark.

Foundry loads the whole image as one texture, and many graphics cards cannot load one wider or taller than 8,192 pixels. Hexer renders at about 4x and steps down to 2x or 1x to stay under that limit; the dialog tells you when it did. If even 1x is too large, the dialog warns that Foundry may refuse the scene. Hexer cannot split a map into tiles, so use a smaller map or a coarser level.

Import it into Foundry

Foundry has no built-in importer for this format. Install the Universal Battlemap Importer module, enable it in your world, then open the Scenes tab and choose Universal Battlemap Import. Pick the .dd2vtt file. The scene arrives with the image, the grid size and the walls.

Grid alignment

The imported scene starts on a square grid, whatever your map looks like. Change the grid type in the scene’s configuration to the hex type the Export dialog names:

Hexagonal Rows — Odd for a map with pointy-top hexes.
Hexagonal Columns — Odd for a map with flat-top hexes.

Or click Copy Foundry macro in the dialog, paste it into a new Script macro in Foundry, and run it while the imported scene is open. It sets the grid type and nothing else.

Leave the grid size and offset alone. Hexer has already made them match:

Grid size is the width of one hex from flat side to flat side, which is how Foundry measures a hex grid, rounded to a whole number of pixels. The importer may lower it along with the image if the image is too large for your graphics card, which is why the macro does not touch it.
Offset: Foundry lays its hex grid from the image’s top-left corner, with the first hexes centred on the edge, half off the image. A map drawn flush to the corner would sit exactly half a hex out of line. Hexer adds a parchment border sized to match (one and a half hexes on one axis, a whole pair of rows or columns on the other) so every hex centre lands where Foundry expects it, and the odd rows or columns stay the odd ones.

When the grid does not line up

Every other row or column is half a hex off: the grid type is the Even variant. Choose Odd.
The whole grid is shifted, or drifts further off across the map: the grid size or offset was changed after import. Import the file again rather than nudging it back by hand.
Squares instead of hexes: the grid type was never set.

Other virtual tabletops

Other tabletops that read Universal VTT files get the same image, grid size and walls, but the grid hint and the macro are written for Foundry. In any of them, set the grid to hexes yourself.

Roll20 reads the file directly: in the Page Menu, choose Upload Background and pick the .dd2vtt file.
Owlbear Rodeo cannot open the file on its own. Use the Scene Importer extension, below, or export a PNG and use it as the map.

Owlbear Rodeo with the Scene Importer

The Scene Importer is a free community extension that builds an Owlbear scene from a .dd2vtt file: the map image at the right scale, plus walls from the edges you blocked, for the Dynamic Fog extension. It is not listed in Owlbear’s extension store, so you add it by its address:

In Owlbear, open Profile, then Extensions, and choose Add Custom Extension.
Paste https://scene-importer.pages.dev/manifest.json and add it, then switch it on in your room’s extensions.
Open the Scene Importer, pick your .dd2vtt file and create a new scene.

The scene always starts with a square grid, because the file has no field for hexes. Open the scene’s grid settings and choose a hex grid. The hexes can then sit a few pixels off Owlbear’s grid: the export is lined up for Foundry, and Owlbear starts its grid elsewhere. Select the map, use Align to drag one hex onto the grid, and set the cell size once.