Importing DEM Files into Manifold and Launching 3D View Studio

USGS DEM files are often used as sources of terrain elevation data in maps. This topic walks through the entire process of downloading a DEM file, uncompressing it, converting it into a Manifold map and displaying data in 3D View Studio. A few customers new to Windows find some of the details of file opening and unzipping troublesome, while Windows people often find the .gz compression used by USGS confusing. This examples covers each baby step in tedious detail so you can check your procedure against it.

	Visit the USGS page at the above URL. Make sure you download the 1:250,000 scale DEMs and not the "SDTS DEM" files, which use a different format.
	We've clicked on the link to download by FTP, have selected Arizona, and are about to download the file called ajo-e.gz
	Create a directory called c:\example and place the ajo-e.gz file there. Before unzipping it with WinZip 7, set the WinZip 7 options as shown (ie, uncheck the TAR file smart CR/LF conversion box).
	Double-click on ajo-e.gz to launch WinZip with it. We are using WinZip 7. Tell it to use the filename ajo-e.dem as shown in the screen shot. Press OK. In the main WinZip dialog press Extract. This creates a file called ajo-e.dem in c:\example. Close WinZip.
	From the Windows Start button, choose Programs - Manifold System - Manifold DEM Converter. Change the Acc to 5, press the Browse button and browse over to c:\example\ajo-e.dem and open it. We set the Accuracy to 5 because this is a simple example and we want to import only a small number of points from the (enormous) DEM file.
	Press the Refresh button. After the refresh it looks like the screen shot.
	Press the Export button. Give a filename of ajo-e to use in the Save As dialog as shown in the screen shot. Note 1: In standard Windows "Save As" dialogs, providing a three letter extension in the filename box will override whatever is chosen as the standard extension by the "save as type" box. Press Save. Note 2: To guard against inadvertent errors, Service Pack 2 for Manifold Release 4.50 alters DEM Exporter to strip off the ".dem" extension by default when clicking the Export button. So, if one simply clicks through the Export button's "Save as" dialog the file will be saved with a .mfd extension.
	This creates the standard Manifold file pair ajo-e.mfd / ajo-e.mdb as seen in the Windows explorer screen shot. The .jpg files are the screen shots being created for this example. Close DEM Converter
	Launch Manifold. Click on File - New to launch the new map wizard. It opens as shown.
	Press the browse button next to the MFD name, browse over to c:\example and double-click on ajo-e.mfd
	This loads the MFD and MDB name boxes with the correct names in the New map wizard. Press Finish.
	Manifold loads the new map: it's a grid of points.
	Launch Solvers - 3D View - 3D View Studio (Points Only) as seen in the screen shot. Note: The menu shows various additional solvers that are not part of the commercial Manifold product releases. These are test versions that were installed on the machine used for these screen shots.
	Choose the layer ajo-e as the point set and the elevation field for elevation. Since there are not so many points (due to the Accuracy value of 5 used in the original DEM converter settings) we will use the entire layer's worth of points in 3D View Studio. If the DEM had been imported with higher accuracy, we would have selected some subset of the points and use the Selection as the point set. Click OK.
	Our example machine (dual 266Mhz PII) computed for about 15 seconds with this many points before displaying 3D View Studio.
	Click the up arrow on your keyboard to zoom in and the left and right arrows to "spin" the display left and right. Click and drag with the mouse in the 3D View window to "tilt" the display. Yep! that's definitely Arizona... we'd know it anywhere on sight. :-)

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