2025-07-28 00:00:00 You can convert map images to GPS maps, and you can use the created maps completely offline. Custom Maps works on phones, tablets, and on Chromebooks. Custom Maps can use maps in JPG and PNG images and PDF documents. You can find useful map images in national and state park brochures, many of which are available online. You can also take pictures of paper maps. You can create your own GPS map for the park from those before you get there, so you will know where the trails lead and where the facilities are.