Creating Map Assets from For-Print Media

Here are a variety of images that count as "Map Art" that a GM would place on a Page of the VTT that would be pulled from (or composed from) For-Print Media:

  • Battle Maps: Probably the most commonly thought of when it comes to TTRPGs. These images diagram a dungeon or a particular terrain area where tokens will be placed and moved around on. Typically these are set at a defined scale and can either have a grid or without and are viewed top down, but can also use an isometric or dimetric perspective as well.
  • World/Town Maps: This is the more traditional map graphic. This could be a map of a village, a kingdom, a continent, a world, a galaxy, etc. If it's a map that's not meant for precise Token positioning, it falls under this category.
  • Landing Page Graphic: In Roll20, a Player can join a game they've been invited to at any point and time. Between play sessions, it's always a good idea for the GM to set the Player Ribbon on a Page unrelated to the current happenings of their campaign. Most Marketplace Modules and Addons that come with Page content often include a Page that displays the cover art of their content.
  • Dashboards and Playmats: These Page graphics are often used for rule systems that use more theater of the mind mechanics or are for a game that leans closer to a board or card game. It makes play more aesthetically pleasing than using a blank Page.

Converting Non-Battle Maps for Roll20

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Converting Battle Maps for Roll20

The primary objective with your map artwork is to be immediately playable, or as close to it as when a GM loads it up in the VTT. As such, when preparing your battle maps, make the following considerations:

How many pixels make up a grid unit on the artwork? The closer the map's resolution is to 70 x 70 pixels per grid square, the better. Better still if the resolution is larger. If the native resolution will support it, and the map is not overly large, you may use 140 x 140 pixels per grid square. Many users play at higher than 100% zoom, so using a higher resolution image will present a clearer map image. This should not be done at the expense of VTT performance. Maps that will require complicated Dynamic Lighting or are larger than 30x30 grid squares in size are probably not good candidates for using a larger pixel per grid square resolution.

Not Using a Square Grid? Here are the grid resolutions for the other grid types available in Roll20. If your map is less than 30 units in a given dimension, you can also use a larger pixel-by-grid-unit scale. The following are the pixel estimates for each grid unit at 100% Zoom on Roll20’s Tabletop:

  • Hex Grid (Vertical): ~75px wide by ~88px tall
  • Hex Grid (Horizontal): ~94px wide by ~81px tall
  • Isometric Grid: ~121px wide by 70px tall
  • Diametric Grid: 140px wide by 70px tall

Is this map’s drawn-on grid set to the correct scale? TTRPGs that use positional tactics, such as Pathfinder and Dungeons and Dragons, use battle maps where each square grid cell represents a 5-foot area. Sometimes, to save on print space, a battle map might be drawn at 10, 20, or more feet per square. This might require removing or adjusting the grid drawn on the map itself, if possible. At worse, you can subdivide Roll20’s grid to provide the correct scale after importing the image into the VTT. With this latter approach, there will be some visual conflict between the artwork’s grid and the vector one drawn by Roll20.

Does the map have an irregular grid? Sometimes in the process of assembling a for-print book, a battle map can become slightly distorted, causing the grid to no longer be square. These situations might require considerable repainting of the grid if it can't be fixed by shifting or re-scaling the image. It is strongly advised that you use the measurement tool in your image editing software to take several readings of the distance between several points on the grid of your maps very early on in your marketplace conversion in case heavy image editing is required.

Are there map secrets that need obscuring from the players? As mentioned earlier in this guide, maps designed for printed adventures will have information on them that is designed to be GM-facing. Room/area numbers, location labels, secret doors, and traps are all examples of such elements that are intended for GM eyes only. Identify which elements of the map need to be obscured from the players. These elements will need to be isolated from the artwork and saved as individual images that will be later placed on the GM Info Overlay Layer so they're not visible to the Players of the game.

Are there multiple maps contained within one image? This situation occurs when multiple floors of the same location are collected into one map. These floorplans are not always aligned to the same grid. This will require some shifting and resizing of the individual floors so their grids align.

Does the grid fall off at the map edges? This isn't necessarily an issue, but it's important to check your grid measurements if you have a map where the grid fades off and doesn't reach the border of the image. The map might crop the grid off in fractional amounts which could cause alignment pains when placing the image on the VTT. You might want to consider cropping out, or extending, the border so that the image ends directly on a grid line.

Where can you add value to your map? Simply put: Are there any ways in which other Roll20 VTT tools could strengthen the player's experience of a map? Examples of this would be the "Gears of Hate" map in Wizards of the Coast’s Tomb of Annihilation campaign. By using a Rollable Table Token on the Map and Background Layer, we were able to give the GM the ability to switch between the multiple positions of the massive dudgeon gears.

Adjusting Battle Map Grids within Image Editing Software

The following walkthrough will be focusing on adjusting your maps to fit a square grid. Most of these steps will also work with the other available grid types. Simply make the dimension adjustments as listed above under the “Not Using a Square Grid?” section.

You will have a much easier time aligning your art to the Roll20 VTT grid if you do some minor tweaks to the configuration of your image editing software preferences before making adjustments to your map art files. We'll be showing the settings as they appear in Photoshop, but most software will have comparable parameters.

Adjusting Your Preferences
Photoshop's Preferences Menu can be accessed from the top menu bar (Edit → Preferences) or by pressing Ctrl + K (by default).

Measurement Increments

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Under the Units & Rulers tab, set the Rulers option to Pixels. Inches, centimeters, and other physical measurements don't have any bearing on the VTT. Setting this default unit value will adjust the rulers, measurement tool, and many other tools within Photoshop to use pixels.

Grid Setup

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Under the Guides, Grid & Slices tab, set the Grid's Guideline Every value to 70 Pixels (or 140 pixels if appropriate). This will make it considerably easier to align the map to the grid in the later steps.

It might also be a good idea to change Photoshop’s Grid Color to Magenta or some other contrasting color that will be clearly visible on a majority of your maps. Black, blue, and other dark colors tend to be prevalent on many maps, and thus are harder to distinguish from Photoshop’s in-application grid.

It might also be preferable to keep the Grid Subdivisions to 1, thereby reducing the visual clutter when attempting to work with the maps. That being said, there may be other instances, where you’re dealing with non-5-foot-square grids, in which having subdivisions is advantageous.

When you have completed these changes, click OK.

Familiarizing With and Creating Custom Hotkeys

There are several hotkeys in Photoshop that can be very useful while map editing and exporting images. 

Photoshop's Keyboard Shortcuts menu can be accessed from the top menu (Edit → Keyboard Shortcuts) or by pressing ALT + SHIFT + CTRL + K (by default).

Grid Toggle and Snapping

You can toggle the grid on or off in Photoshop using the Hotkey CTRL + ' by default. You can toggle snapping to grid by using the Hotkey CTRL + SHIFT + ; by default.

Export Shortcuts

You'll find that creating custom shortcuts for the following export commands very helpful:

Shortcut for File → Export → Quick Export as PNG. This shortcut allows you to immediately output what you can see on screen as a PNG file. This is useful not only for the process of making maps but also making location markers, tokens, etc.

Shortcut for File → Export → Layers to Files. This shortcut allows you to select layers via the layer palette, and then immediately output them in a variety of different file formats. This can be useful for GM Eyes-Only text, secret doors, etc.

Organizing Map Image Files (Optional)

If you include all the potential GM Overlay objects, a single battle map can generate a number of individual image files. To keep everything organized, we recommend using a file structure dedicated to each map. This is the method Roll20 uses internally for organizing map files:

  • Separate each battle map art file into its own folder, using the same naming convention as the map. Once you start using export commands such as "Layers to Files", the resulting images will be conveniently saved within this folder.
  • Create a GM Layer folder for each map too. This folder should go inside each individual map folder and will be the location to which all of the map labels, trap icons, etc. are saved.

Resizing the Battle Map

Once your imaged editing software preferences have been customized as desired, it is time to start editing your map artwork. There are two essential steps for every map and a variety of context-specific situational steps contingent upon the specific requirements of each file.

Increase Map Size (Situational). If the map is scaled in such a way that each grid square is smaller than 70 x 70 pixels, the first task will be to upscale the map. Generally, you will want to use Photoshop's Image Size menu for this (Image → Image Size or ALT + CTRL + I). It is advisable to get the resized image as close to 70 x 70 as possible*, but you don't need to overly concern yourself with precision at this point, just ensure that it is at least 70 x 70 pixels.

*If you’re working with a non-square grid, then use our listed dimensions earlier as your target.

Remove/Edit Grid (Situational). If the map's grid is either inconsistent (warping occasionally occurs if you're exporting graphics from a PDF), in the wrong scale (i.e. 10-foot-grid for a 5-foot system), or if the map requires a high degree of repainting, it might be beneficial to remove the grid from the map altogether. This might be as simple as disabling the layer on the art file or it might involve manually painting over the grid.

Edit Map Layer (Situational). Often, the map layer will have certain undesirable elements 'baked' in (i.e. flattened into the layer). During this step, things such as secret doors, traps, text, and other unwanted elements should be painted out once copies are extracted and saved for the GM Layer.

Lining Up the Grid (Mandatory). Once all edits have been made to a map it's time to align it to the image editor's grid. The easiest method for doing this is as follows in Photoshop:

  1. Zoom into the center of the map.
  2. Select all of the layers in the layer palette and align one of the artwork's grid intersections with a Photoshop grid intersection. You can temporarily turn off Snapping in Photoshop by holding CTRL while dragging the map.
  3. While all layers are still selected, under the EDIT menu, select Transform→ Scale (CTRL+ALT+T or Free Transform from the context menu).
  4. If the Transform origin point isn’t visible, go to the top icon bar, and click the "Toggle Reference Point" check box to reveal it.
  5. Hold down the ALT key and click on the point of the matching grid intersections to relocate the transformation origin. Alternatively, you can drag and drop the Origin Point at this intersection.
  6. Zoom into one of the map’s corners and ALT+drag the handles to line up the grid lines here. (If the proportions are not constrained during resizing, we can additionally hold SHIFT to do this).
  7. Repeat step 6 for the remaining three corners of the map until the artwork is entirety lines up with Photoshop’s grid.
  8. Confirm the transformation by clicking the :check_mark: in the action bar, or by pressing CTRL+RETURN.

Crop Map (Mandatory). Once the map has been aligned, crop the map down so the perimeter of the image falls on a grid line. This step ensures that the map presentation is not only tidy but also allows for easier import into the Roll20 VTT.

 

Return to For-Print Image Guide Index
<< - Prepping For-Print Art for the VTT   Creating Token Art From For-Print Media -  >>
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