These are out right the highest quality landscapes for infinity available. Although the 2048x1080 version of this plugin is included with infinity, you can easily download and replace it with this one if you think your computer can handle the extra load.
This is a high resolution landscape plugin for Marathon Infinity. It replaces all landscapes with 4096x2160 PNG versions.
Please note, if your copmputer have difficulties at using these large landscapes, there's an alternative download, where all landscapes have been reduced to 2048x1080. Check out: http://www.simplici7y.com/items/gorans-highres-2048x1080-landscapes-plugin