3D Utility Example

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The 3D Viewer is accessed from the Utility menu.

Viewing a map in 3D requires two files: a Digital Terrain Model that provides elevations and an overlay image. The DTM can also be viewed alone with simple color shading.

The basic technique to use the utility involves creating DTM and overlay files with the same boundaries. It is not critical that the two files share the same projection since the 3D Viewer does not reference spatial coordinates.

Instructions for two methods to create the files follow.

  • Method A - Based on creating an overlay for use with an imported Digital Terrain Model (DTM) in the following formats:

  • Method B - Based on using a TIF DTM and BMP overlay created with the fGIS "Export View to 3D" utility.

 

Method A: USGS DEM and Matching fGIS Overlay

1. This 3D view was made by combining a USGS 30-meter Digital Elevation Model (DEM) and an overlay image exported from fGIS. Although the USGS DEM uses a UTM/NAD 27 coordinate system and the fGIS overlay image has WTM/NAD 83 coordinates, the two layers line up well if the boundaries match.

 

2. This image above shows a view in fGIS that is set up with the data used for the image overlay. The heavy yellow lines are from a USGS quadrangle index shapefile. It was used as a "cookie-cutter" guide with the fGIS "Export Image Tool" (selected in the toolbar and used at 2X resolution). Save the Exported Image as a BMP file to use as the 3D overlay file.

3. Start the 3D Utility (Utilities>3-D Viewing>Launch 3-D Viewer). Load a Terrain Model by using the DEM extension option. Browse to find the USGS DEM that corresponds to your view. When the landscape loads, you'll see a simple "hillshade" view like the one above.

Use your mouse to reposition the view. Shift + the left mouse button will raise or lower the landscape. Ctrl + the left mouse button will rotate the view on a center (y) axis. Alt + the left mouse button will rotate it on the x or z axis. With the left mouse button depressed, pull the mouse toward or away from you to zoom out or in.

4. Now apply the the Surface Overlay Image (saved from step 2) to make a 3D map. The ortho photo layer was turned off but the vector lines were kept for the following overlay.

The 3D Viewer interface (partially pictured above) allows many Render adjustments for terrain color, lighting, image size, etc. Play with the controls to see what they do.

Note that the data used in this example can be downloaded in the "State_Park.zip" sample file (which includes the DEM).

A USA Quadrangle Index in geographic coordinates and a Wisconsin Quadrangle Index in WTM (both as fGIS project folders) can be downloaded from Digital Grove to help frame your image overlays. See the Digital Grove Links page for DEM sources.

Note: You might also want to try the fGIS image export/overlay technique with 3DEM or LandSerf. The procedure is somewhat more complex in those programs, but they offer additional features including image animation and GPS support.
 

Method B: Export fGIS View to 3D

 

The 3D Viewing utility includes a tool (above) that will export DTM and overlay files with identical boundaries. It requires that some sort of DTM image layer be included in an fGIS view.

The 3-D Viewing > Export View to 3-D dialog outputs four standard image widths. The 3-D viewer software does not operate properly unless the input DTM image width has an even number of pixels. Also, the 3-D viewer software locks-up if the input image is too large. Keep the DTM TIF layer relatively small. 640 or 800 pixels wide is suggested. The image feature size can be boosted, but 2x is usually enough (makes text or vector objects bigger). Specify a "tif" extension for the Output DTM and a "bmp" extension for the Output View Image.

To load the TIF DTM in the 3D Viewer, be sure to select the "tif" file type in the dropdown menu. The quality of TIF DTM image is directly related to the resolution of the TIF layer. Lower resolution images will produce a blocky terrain model. (The State_Park.zip example file includes a "gradient_dem_ecw.ecw" that produces good results when used as the base for creating a TIF DTM with the utility. Change the grid spacing in the 3D Utility to 10 x 10 for best elevation results.)

 
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