Please note that 7.5’ DEMs cannot be merged across UTM zone boundaries. Mixing DEMs of different resolution will result in an error message “DEMs Have Different Grid Resolutions.” That is, 10-meter and 30-meter resolution DEMs cannot be mixed. Please note that 7.5’ DEMs to be merged must be all of the same resolution. 3DEM makes the best match possible with the selected DEMs.
![terragen 3 tutorial terragen 3 tutorial](http://3.bp.blogspot.com/-xoGCZy4iowU/UfC1gO7uAeI/AAAAAAAAv5A/_1ERh1QoNwM/s1600/0lpdfekv.jpg)
Note that merged DEMs do not always match perfectly at their boundaries since the quality and accuracy of each DEM can vary widely. The only limit to the number of DEMs that can be merged is memory in your computer.ĭEMs to be merged must be adjacent to each other. To select multiple files, highlight each file required using the mouse, and then click OK to load all files into 3DEM. That is, all of the DEMs to be merged must be contained in the same file directory. Choose “File - Load Terrain Model” and select “USGS DEM.” Then you can select multiple DEM files from a common directory to be merged into one Overhead View. "USGS 7.5 Minute SDTS DEMs in tar-gzip (*tar.gz or *.tgz) format can be directly merged by 3DEM. About merge, this is what 3Dem help has to say: If the zone you are interested is splited in two or several DEMs, will need to merge them. Export it: File/Save Terragen Terrain/ Entire or Zone, what you want.ģDEM is also capable of another interesting operation: you can merge several DEMs. There is no problem if you plan to use it for 3dskybox. Take in consideration that DEM size is much bigger than the max distance supported by Source, so you need to crop smaller areas or your terrain will look scaled in-game. Select zone can be resized pressing left mouse button while dragging on a corner. Load Terrain model: choose USGS DEM file type But before you can see your DEM in Terragen, you need to convert it with 3DEM Terragen is a nice app to create terrains with very realistic atmosferic effects (you don’t need Terragen for this tutorial). Second step: convert DEM to Terragen format with 3 DEM. Choose 10 meter, if there is no 10 meter don’t expect the best results. When you are about to download, probably there will be two options: 30 and 10 meter resolution. Start digging into the geocomm database, and sooner or later you should be find it. Now you have all you need to find your DEM. Use it to find the exact place by typing its name, then take note of state/county/USGS Quad and latitude/longitude. Search is broken (at this moment), so things will complicate a bit. You will need to know the state and county in that case. You can get the first file you see, or look for a specific place. Need to register (free), and downloads will be restricted at 5 kb/s, but each DEM is only 3 MB max. There is a huge database with the entire USA country here: Sample DEM and VMF included.įirst step: Obtaining DEMs. This is a tutorial to create realistic landscapes based on digital elevation models (DEM) from real world places.