Large Export macro/script issue

Has anyone else noticed that using the Large Export script from the 2017 Annual reduces the vertical resolution by the number of vertical tiles?

I made a massive desert map that is supposed to be 16,200 x 10,800, but it exports at 16,200 x 10,797. I am assuming that it has to do with the stitching that ImageMagick is doing, but I'm not quite sure.

I am using this for a VTT (Virtual Tabletop) so getting the pixels to match perfect with the faintly rendered grid is something I'd like to do. I know I CAN just add the grid later, but in some of my more detailed maps I place the grid artistically below certain layers so that trees, walls, and non-passable terrain don't show the grid.

I am also really proud of this one, since I made it in 9 tiles (3x3) and managed to move the sand dune contour lines so that their glow effects is rendered perfectly in each of the 9 tiles. This was difficult, as you can see form the two images below, the before and after.

Comments

  • At first, I was running into problems with the effects when exporting in tiles, but I corrected it by moving the dunes to lcoations where they wouldn't hit the borders, and I was able to get it right.
  • Then I got it just right... but the resolution was off by 3?
  • And yes I know I need to make lots of adjustments everywhere, I am just getting started and wanted to have a solid foundation before I started adding detail.
  • MonsenMonsen Administrator 🖼️ 46 images Cartographer
    I can't guarantee that I haven't made a mistake somewhere in the script, but I haven't encountered a consistent off by one pixel before.

    But there are a couple of things I can think of:
    1. your map aspect doesn't fit exactly to the value given for the tiles. To take a more extreme example to illustrate, if you have a map that is 800 by 600 map units, and you export it as a 2x2 tiled map, each tile will be 400 by 300 map units. If you have told CC3+ that the til sizes are 4000 by 4000 pixels, they will still end up being exported as 4000 by 3000 to fit with the ratio. If you have a minor discrepancy between the map ratio and pixel sizes for the map, this can theoretically happen. I would say chances are increased for it happening if the map size is not evenly divisible by 3, as this gets us into floating point precision territory.
    2. Sometimes, CC3+ exports are 1 pixel off. In the tile script, all tiles are automatically resized to the dimensions of the first tile, ensuring they are all 100% identical sized (anything else would leave weird white stripes in the map). But if the first map tile is indeed 1 pixel off, this procedure will force them all to be one pixel off


    But if the 3 pixels off is the only issue in the end, you should be fine by just throwing it into an image editor and resize the map. Those few extra rows of pixels should be distributed evenly, and shouldn't be visible.

    Getting grids to line up can be a chore though, tiled exports or not.
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