Aligning the Grid on imported maps

Configuring Grid Type

Once your map is uploaded, you can assign a specific grid type to it depending on the system you’re playing. From the Left Handed GM Sidebar, click on the hamburger menu as shown in the animated image below.

From there, this menu will open:

As my map is a square grid map, that's what I'll be choosing.

Lining up the grid with the map (Or choosing not to...)

This is the part that requires the most work. After experimenting a bit, it'll become easier and more intuitive. If you've been following along with a map that has a grid, you may notice that Astral's grid is not lining up with your map's grid. 

"That's okay, I'll just disable Astral's grid."
This is nice, in theory, but doing so can cause issues with token placement and accurate distance measuring. Tokens will only snap to Astral's grid, not to where your map's grid points are. This also is true with the ruler. You can disable snap-to-grid and hide Astral's grid, or you can line up the grid entirely.

If you'd like to give it a go without the grid, go into Grid Settings as before and disable both "Show Grid" and "Snap-To-Grid" and you're all set! No more work needed. If you'd like the convenience of token snapping and accurate distance measurement, this next part is for you.

My map is on the stage, but it's clearly not lining up with the grid. The map's grid squares are much smaller than Astral's grid, and they are misaligned. It's a mess. So, let's try to estimate a size requirement for the grid.

I can see that there are about 4 grid squares per Astral grid square. So let's take Astral's grid size down by 75%.  Originally 70, let's take it down to 18. 

Almost instantly, we're already in a much better position. Now comes the fine-tuning.

Rather than trying to input the correct number to the nth decimal, we'll turn to the map asset's bounding box to fine tune the grid. First, let's shift the actual asset to best fit the top corner to the grid. I'll turn Snap-To-Grid on (if it wasn't already) and see how close that gets me. Then I'll disable snap-to-grid for fine-tuning.

In most cases, Snap-To-Grid will line up your top corner with the grid easily. Let's move to the bottom center of the map and align the grid height. We'll stretch the grid until it lines up perfectly, top to bottom. Continue to check the upper left hand corner, following the squares down until they start to deviate, then stretch again and repeat until it starts to look like this:

We can see that the grid is aligned properly top-to-bottom, but we need to stretch the map to the right to finish the lineup using the same method. The end result will look like this! A nearly perfectly aligned grid. 

From this point, it's usually best to disable the Astral Grid visibility, so you don't have thick or ugly looking grid lines. If you leave snap-to-grid on, your tokens will still behave normally even though the Astral grid is hidden.