Importing Digital Elevation Models

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Ontario Digital Elevation Model | Canadian Digital Elevation Data (CDED) | DEM from DMTI Spatial | LandInfo SRTM Digital Elevation Model Data | Digital Terrain Model of Southern Ontario

General Instructions

1. Download the file from the web site
2. Navigate to the location of the DEM on this Web page, select a DEM, and save to your local folder.
3. Navigate to your folder and unzip. If the zipped file has a .exe extension, double-click to unzip. If the file has a .zip extension, right-click and choose the option Extract all Files. Save the unzipped files to a local directory (for example, c:\temp).
4. Open the mapping software (ArcView 3.x / ArcMap) and add the DEM.

Detailed DEM Import Instructions

Ontario Digital Elevation Model (Ontario Ministry of Natural Resources)

The .dem file is a binary floating point number file. The .hdr with the same name as the .dem file is the header file, and is required to be in the same directory as the .dem file.

ArcGIS 9

the unzipped file contains .dem and .hdr files.

1. In Windows Explorer, change the extension of the .dem file (xxx.dem) to a floating point file xxx.flt.
2. In ArcToolbox, navigate to Conversion Tools > To Raster and double-click the Float to Raster too to open. The Input float file is the .flt file in your local directory.

ArcView 3.x

1. Set working directory: File > Set Working Directory (e.g. c:\temp).
2. The spatial analyst extension must be turned on: File > Extensions > Spatial Analyst.
3. To import the DEM: File > Import Data Source. Select the file type as ASCii and navigate to the *.dem file. In the Import Dialog, make sure All Files is selected. The processed grid will be saved to the working directory.

Canadian Digital Elevation Data from GEOBASE (Natural Resources Canada)

Download the NTDB files (1:250,000 and 1:50,000). The unzipped file contains 2 files: deme_e.dem (east) and deme_w.dem (west).

ArcGIS 9

1. Open ArcMap & ArcToolbox.
2. In ArcToolbox, navigate to Conversion Tools > To Raster and double-click the DEM to Raster Tool to open.
3. Navigate to the dem file in your local directory and click open.
4. In the Dem to Raster dialog box, accept the default ouput grid file name or change to something more descriptive. Click OK.

ArcView 3.x

1. Set working directory: File > Set Working Directory (e.g. c:\temp).
2. The spatial analyst extension must be turned on: File > Extensions > Spatial Analyst.
3. Choose File > Import Data Source.
4. Select USGS DEM as the import file type.
5. Navigate to the directory holding the DEM file. Select the file and click OK.
6. At the prompt to name the output GRID file, either accept the default name or provide a more meaningful name and click OK.
7. When the DEM has been imported, you will be prompted to add the grid as a theme to the view. Click Yes.

The default coordinates for the CDED data are decimal seconds. You must use an Avenue script (demshft.ave) to convert the data to decimal degrees. First, you must work through the procedures outlined at the Brock University map library Web site before overlaying other datasets.

Digital Elevation Model from DMTI

The unzipped file contains two files: .txt & .prj. The DEMs are floating point grids which can be added as integer or floating point.

ArcGIS 9

1. Open ArcMap & ArcTool Box.
2. Expand the folders: Conversion Tools > To Raster and double-click the ASCii to Raster to open.
3. In the ASCII to Raster dialog box, navigate to your local directory, select the .txt file, and click open.
4. The dialog box is populated with an input file — the .txt file and an output file. Select the output data type as Float.
5. Click OK to run the tool.
6. A status box will popup and provide a status report on the progress of the conversion. When it is finished, the grid will be added to the map.

See also: Generating a 3D image from a DMTI DEM at the University of Toronto Map Library.

ArcView 3.x

1. Set working directory: File > Set Working Directory (e.g. c:\temp).
2. The spatial analyst extension must be turned on: File > Extensions > Spatial Analyst.
3. From the file menu, select Import Data Source and then Convert Data to Grid.
4. In the Import Data Source dialog box, select ASCii Raster. Click OK.
5. When the Import ASCii Raster Files dialog box appears, navigate to the folder where the ASCii file is located. In the Import Dialog make sure All Files is selected.
6. Select the .txt file and click OK.
7. When the Import Grids Dialog Box appears, click No to add Cell Values as integers. The DMTI DEMs are floating point grids.
8. At the prompt to Add Grid as Theme, click Yes. The grid is given a default name by ArcView. You can select a different file name. Save in your working directory.

Digital Elevation Model – LandInfo

The unzipped file contains these files: .aux,.bil,.hrd,.prj,.rrd,.sta. BIL is simple binary raster format.

ArcGIS 9

1. Open ArcMap, click the Add Data button
2. Navigate to the local directory, select the .bil image and click Add.

ArcView 3.x

1. Click the Add Data button and navigate to the directory where the unzipped files are located.
2. Make sure in the Data Source Type that Image Data Source is selected.
3. Click the .bil file to select and click OK.

Digital Terrain Model of Southern Ontario

Represents a topographical surface, specifically a regular grid of spot heights. The format is .dwg

ArcGIS 9

Please see Generating Contours from a DTM at the Ryerson University Map Library for deatils on this process.

ArcView 3.x

Not available.

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