Fanning Software Consulting

Navigating GOES GeoTiff Images

QUESTION: I download a number of GOES East and West GeoTiff images from this NOAA web page. Can you show me how to annotate these GOES images with continental outlines and map grid lines?

ANSWER: Yes. This is most easily done with the cgGeoMap program from the Coyote Graphics map routine library. I will use the file GoesEast04I23451615.tif from this web page in the example below.

First, I create a map coordinate object by reading the GeoTiff file. In this case, I also return the image so I can display it later on. (The image display can also be driven from keywords to cgGeoMap, but I think it will be more useful to you to see the individual steps in the process.)

   file = 'GoesEast04I23451615.tif'
   map = cgGeoMap(file, IMAGE=image)

Next, I create a window to display the image in and display the image with a two-percent histogram stretch.

   cgDisplay, XSIZE=900, ASPECT=image
   cgImage, image, STRETCH=2

Next, I make sure the map object is set up to cover the entire window, and I set up the map projection space.

   map -> SetProperty, POSITION=[0,0,1,1], /NOBORDER
   map -> Draw

And, finally, I draw the continental outlines and map grid lines on the image.

   cgMap_Continents, COLOR='dodger_blue', MAP=map
   cgMap_Grid, COLOR='goldenrod', MAP=map, /LABEL

You see the result in the figure below.

A GOES East image with annotation.
A GOES East image with annotation.

Version of IDL used to prepare this article: IDL 7.1.

Written: 26 December 2011