This tool was made to add a patch details (high resolution) to an existing database (ive) without rebuilding everything. The algorithme is very simple, it builds with osgdem the part of patch you want, using very low res data for the rest of world, when the build is finished you have to report the patch coordinate tile in the osgDB::DatabasePager (a modified version) with the directory where to get those new data. Then in real time the osgDB::DatabasePager will make the hook based from filename request by a osg::PagedLOD (the name contains the tile coordinate), if the coordinates are inside the ‘box’ of the patch we built we will use data from the new directory. With this process you can make a low res Earth, and after build details part as you want, it can be used to run multi-process of osgdem for differents details zone on a multi core processor. In the screenshot, i use a very low res earth and a higher res for the france, the france was pre processed on another machine. I configured the DataPager patched to get it.