Aligning Maps
From Roll20 Wiki
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Using The Align To Grid Tool
Sometimes you might want to use a pre-made battlemap that already comes with its own gridded surface. If you're having difficulty getting your image's grid to match Roll20's, we have an alignment tool that will make this task easier.
- Zoom in to 150%
- Make sure you're on the Map & Background layer
- Right Click on your map image and choose Advanced -> Align to Grid
- Click and drag to trace a 3x3 (three across & three down) square box aligned with the grid on your map (we're ignoring the Roll20 grid for right now). You don't need to be pixel perfect here, but the more accurate the trace, the less fine-tuning you'll need to do later on.
- When you let go of the mouse, a new window will appear. If you're satisfied with your tracing, click on the "Align to Grid" button to confirm.
- The Grid Alignment Tool should resize your map to match fairly closely to Roll20's grid. Use the horizontal and vertical scaling transformers on your image to fine-tune the grid alignment.