And creating contours using that data is much easier than you think.
Digital Elevation Model (DEM) depicts the elevation of a surface between known elevation points. This tutorial shows you how to use Google Earth’s elevation data to generate a DEM. In today’s world, DEMs are mostly used in GIS applications.
Of course, We can download the Digital Elevation Model (DEM) from the USGS website. But if we want to know the elevation data of a location and with no time to download coordinate-wise DEM, we can create a beautiful contour map by just using Google Earth, any GIS software and a free third party data format changing utilities like GPS visualizer or mygeodata.cloud.
Here is a stepwise tutorial for creating a DEM using Google Earth and drawing contour using ArcGIS.
1. Creating a kml file in Google Earth for our area of interest
When we open Google Earth and move the cursor around, we can see the elevation changing in the bottom right corner of the window. If your screen shows 0 meters, you should check the terrain checkbox in your left layers pane. If it is off, check on the terrain box.
Here, I have selected the Salmon valley area in British Columbia, Canada. In this location, we have a lake, valley and all. The aim is to cover all kinds of terrain types. After zooming in on the region of interest, draw a path that includes as many points as you can. The shape is unimportant in this situation; the accuracy will increase with the number of points. You can go crazy like this in the below picture. Give an appropriate name to the path. Later save as my places in the keyhole markup language (.kml) format.
2. Converting the kml file into GPX (GPS exchange )format
In ArcGIS software, we have options to convert a GPX file into features. But before that, we have to convert our kml file into a GPX format. For this purpose, we can use some free online utilities like GPS visualizer or mygeodata.cloud. In this tutorial, I am using GPS visualizer.
Select your kml file and click the Convert & add elevation button. You can download the converted GPX file instantly.
3. Converting GPX file into a raster(DEM)
For this purpose, I am using ESRI’s ArcGIS software. In ArcGIS conversion tools, under, From GPS, we have this GPX to features tool.
Select your GPX file as an input and give an appropriate name and location for the output file. The tool converts your GPX i.e., the GPS data from Google Earth into point features as below.
If we check the attribute table of these points, we can see the elevation column with elevation in meters.
4. Interpolating the points into a raster
For this, we can use the kriging method. Under Spatial Analyst tools in ArcGIS, we have this tool under Interpolation. Give cell size and other parameters as per your requirement. Don’t forget to select the elevation field as the z value field in the tool.
The next step is to choose a suitable symbology for this elevation data, as well as to increase the number of classes to provide more information. Here, the tool filled up the locations without elevation data using interpolation.
Here is the DEM we created using Google Earth Data. Though it is not reliable for slope accuracy for specific coordinates, it is a decent data which you can use to judge the terrain of an area in no time.
Finally, if we want the contour lines, we can add that using the contour tool.
Here, I have given a 30m contour interval. Your DEM created using kriging is your input raster. Select the appropriate color for the contour lines and the labels.
Elevation data can be generated in this straightforward manner using Google Earth.