Hi,
So I am working on a many years long map making project. I am using a scale of 1" to 10 miles and hand drawing it on 9x12" panels of paper. The current size of the map is about 20 by 20 feet. This is obviously too large to see in one place, so I have been using GIMP to panel them together in a digital file. Obviously, this file is getting quite large. I was hoping people might have suggestions on how to reduce the size of the file without reducing the image quality too much. It's only going to get bigger haha. I've got no experience with vector based programs, is that the direction I need to head?

Gimp is a bitmap (raster) editor, works in pixels not feet and inches. It can display in feet and inches but your individual canvas (tile) depends on how it is set up with a pixels-per inch (PPI) value.

Since you started many years ago when the default was 72 PPI the tile size might be 864 x 648 pixels. Then file size also depends on greyscale or colour (RGB) RGB making larger files than greyscale.

Can you give details - pixel size - grey/RGB/indexed or post one of your individual images (a tile)

For a greyscale image one tile might be about 4 MB **in memory** so a complete 20' x 20' image 500+ tiles might be 2 GB - look at the bottom of the Gimp window for size in memory. Colour will be larger again. Not impossible for a modern computer but probably slow-as-a-snail for manipulating. Obviously when saved, the file is compressed and smaller.

Making smaller? The only way in Gimp is scale each tile down (or the whole) but that will result in degradation of the image.

Use SVG? Inkscape can convert a raster image to a vector but it all depends on the image. Better chance with line drawings than colour images. A vector should be smaller than the corresponding bitmap and of course scales up and down without loss of quality.

Stitching together in Inkscape? Never tried 500+ images before. Do not know if practical or possible.