# Download Topographic Tiles

YAAC supports topographic data made available by the U.S. Geological Survey, generated during the Space Shuttle Radar Topographic Missions. A downloader is built into YAAC for your convenience. All you have to specify what area of the planet you want to download, and YAAC will do it for you. Note you must have connectivity to the global Internet for this to work.

Upon selecting the File->Topographic->Download Tiles option, a dialog box will be displayed showing what map data (if any) you have.

The dialog shows yellow dots where you have data downloaded, and dark gray dots where you do not. The red box identifies the area that will be downloaded should you choose to proceed. You can move and resize the red box by changing the center latitude and longitude parameters, and the radius parameter.

You can also choose to download higher resolution (1-arc-second) topographic data. Currently, this data is only available for the United States and its territories. Note the higher-resolution data will take up approximately 9 times as much disk space as the default 3-arc-second data that is available world-wide, and will also take longer to render topographic information on the map. Choose this only if you have a need for such precision data (such as Search and Rescue operations).

If you click “OK”, YAAC will bring up a progress dialog reporting how far through the download process you are and which file it is downloading at any given point in time. This dialog will automatically go away when the download is complete. Note that, if you stop YAAC in the middle of the download, you will only have what was successfully downloaded up to that point. You can also prematurely cancel the download by clicking the “Cancel” button on the progress dialog. Note the cancel will wait until the current tile file is complete before actually stopping.