Printing the Track Centerlines (also seen when zoomed in 1:1) is useful when you later print the BitMap full size for laying out track.
If the Snap Gird is visible then it will be printed on the BitMap.
The dpi (or dpcm if using Metric units) control specifies the number of pixels per inch (or centimeter) in the BitMap. You can enter values from 0.1 to 100. Larger values will result in a larger BitMap file. BitMaps must be less than 32000 pixels in height or width.
The BitMap width, height and approximate file size is indicated.
Note: This command can create a very large file and consume a lot of memory and time.
Pressing the Ok button invokes a File Save dialog so you can choose the file name for the BitMap.
The format of the file depends on the Operating System: on MS-Windows it is a Windows Bitmap (.BMP) file, on Linux it is a X11 Pixmap (.XPM) file.