Chart your data on images of the Earth

TerraChart Excel macro, alpha test version, is available for free download
You are welcome to use TerraChart and it's output as you see fit.
Please contact Dean McGee to report errors.

TerraChart allows you to place various charts on an image of a portion of the Earth. Currently the images supported are screenshots from NASA's World Wind software. With World Wind and TerraChart, you can easily place charts based on longitude and latitude coordinates.

You can construct your own tables of places with geographic coordinates to chart your own data. Currently the YHRD Database data is supported in conjunction with a companion macro, YHRD_Import also included with TerraChart. This macro allows you to chart results from YHRD database inquiries, either individually or you can combine them with values from other inquiries in a single Excel spreadsheet.

TerraChart can export the map to a web page. As an example, see Distribution of DYS390 in Southern Europe

You must enable macros to use TerraChart

When you first open TerraChart_basic.xls, the TerraChart page for creating a New Map is displayed. Type in an output file name and press the "New" button.

Select the image titled "Mediterranean_16.06278E_40.44108N_3230.05.jpg" and press Open.

The longitude, latitude, and altitude associated with the image are extracted from the filename. If the filename does not have this information, you will need to enter it manually into the boxes provided. A set of images are available which already have the latitude, longitude, and altitude data embedded in the filename. In this format, TerraChart can plot geographic data without additional setup. See TerraChart World Images (1.5MB).

TerraChart expects a 45 degree field of view from top to bottom through the center of the image. The latitude and longitude must correspond to the center of the image. The eyepoint must be at the specified altitude along an axis going through the Earth center and the specified latitude and longitude coordinates. This is the default behavior of World Wind V1.3.

Select the "Chart Map" tab to display the chart creation page.

You can have multiple charts in the same workbook. Multiple charts can use the same set of reference data. Choose the chart to work with from the list on the upper left of the page. The top listbox on the right side determines which worksheet to use for the data to be plotted. Select the desired worksheet.

Several elements are required to generate the charts,

Optional elements include:

The data start box is empty, so select the first column of data you want to chart. In this case it is "E:DYS390-20"

Select the last column of data that you want to chart. In this case it is "L:DYS390=27"

Select the desired legend location, give the chart a title if you wish, set chart type to Pie chart, and press the "Make Charts" button.

TerraChart will display a confirmation box that you want to generate or re-generate the map indicated. You should press OK.

Pie charts will be drawn on the map based on the information in the spreadsheet.

If you want to create a web page of the map, click on the "Export" tab.

If the "World Wind Links" checkbox is checked then the output will include a link that will bring World Wind to the location of the chart data. The altitude used will be the altitude for the original image. Of course this requires World Wind to be installed on the user's computer.

If the "Include Info" checkbox is checked andf you have a column in your spreadsheet with the word "info" in the header row then TerraChart will include the contents of the appropriate row of that column in the web page output. This allows you to include textual description of the data or other information.

If the "Show displayed data only" checkbox is checked then only the data that is visible in the image will be included in the web page. Otherwise, all data will be included.

You can select whether the output image is jpg or gif by the Image Type option boxes.

Excel has some idiosyncracies for extracting the image of the chart data. If the legend data is too close to the right side or the bottom of the chart then some of the text will not be included in the output image. This has been fixed for the right side legend, but it is still a problem for the bottom legend. If you want web page output, I recommend that you do not positon the legend on the bottom.

Type in a desired file name and give the page a title.

The default output folder is where the TerraChart Excel file is located. Press OK.

After generating the page, a preview image of the output graphic is displayed. You can see the generated web page in the selected folder. Note that the image has hotspots linking to the data at the bottom of the page. Each data set is linked to display the World Wind location associated with the data. To find more information or download a copy of World Wind, please visit:

Updated on: March 20, 2006
Dean McGee