Reload your save with Squaks at the top left corner of the stage. Turn off layers 1, 2, 4, and 5, and you see the stage background. If you turn layer 5 back on and fly around with Squaks you'll see the background move just like the foreground does. But if you turn all the layers back on and fly past one of the waterfalls you'll notice the background and foreground scroll at different speeds. The fact that they don't automatically line up is the reason backgrounds need to be extracted, although in some games this is not a problem. The waterfalls count as transparencies and while they do line up with the foreground they don't with the background. Also transparencies usually put up the most difficulty when it comes to mapping due to the way the blend with whatever they overlap.
Backgrounds and transparencies can also have the annoying habit of mixing with each other. Backgrounds can be on multiple layers and transparencies can change more then a backgrounds color. Sometimes they do it to foregrounds too. To put the backgrounds and transparency into our map first we need to get them out of the game.
The bgmapper tool I mentioned before, and it's front end, are especially useful here, but not essential:
http://pikensoft.com/programs-bgmapper.htmlhttp://pikensoft.com/programs-upfront.htmlI'll go over how to do this part with both screenshots and the BGMapper extraction tool.
Extraction with screenshots:
With Squaks back at the top left turn off all but the background layer and fly around. Study the pot marks in the rock face until you can see the repeating pattern in them. It looks like it's only about a single screen both left right and up down. So just take four screenshots of nothing but the background, using the same landmark trick you did with the foreground, only with pot marks in the rock face, in a 2x2 grid. Next line them up like you did the foreground shots and look for the edges of the repeating pattern in them. Mark those edges with lines, cut away everything outside the lines, and the lines themselves, and now you have a tile that perfectly lines up with itself so you can duplicate it to make infinite background.
Extraction with BGMapper or other tool:
Make a new folder on your computer somewhere and call it Piken. Into Piken put the BGMapper program an it's little helper UpFront. Go into the Zsnes folder, find the Donkey Kong Country 3.zst file, and make a copy of it. Put the copy into the Piken folder then double click UpFront.exe to start BGMapper through Up Front. In Up Front's main window you should see the names of all the files in the Piken folder. Select Donkey Kong Country 3.zst and click the big words BG Mapper under Up Front's main window. Now you should be looking at a garbled version of the level we are mapping. Play around with the number keys a little to see what everything does, don't worry you can't break anything from this screen. When you're done experimenting press 1 and 2 on the keyboard to turn off the layers we don't want. Next press 0, then 2, to take the largest size snapshot you can and press Esc twice to exit the program. There's a new file in the Piken folder: BGIMG000.bmp. This bitmap file is the background we wanted. It also tessellates perfectly with itself so it doesn't need to be modified in any way.
Next up transparencies.