Analysis Tools for Digital Image Processing

Analysis Tools

The aesthetic appeal of satellite imagery is only one aspect of remote sensing we are fascinated by. Numerous methods of analysis constitute another aspect enabling the visualisation of processes and structures that normally remain invisible to the human eye. Our analysis tools are modelled on typical tools for digital image processing and illustrate the potential of methods of remote sensing with the help of examples:

  • MeteoViewer: The spatiotemporal weather pattern can be observed via the interactive movement of time series images.
  • Image Calculator: This tool serves to offset satellite images against each other (e.g. for the purpose of creating a vegetation index) and to measure data within the images.
  • Image Classifier: Image classification facilitates the process of grouping pixels in "classes" according to their respective reflection characteristics. That way, thematic maps are being created.
  • Swipe: This tool makes it easy to draw a quick comparison between two images and to observe changes within them.

MeteoViewer: The Weather Pattern in the Satellite Film

 

MeteoViewer

 MeteoViewer

The MeteoViewer is an interactive tool displaying current images of the European weather satellite Meteosat-9 (MSG). Due to its particularly high temporal resolution, every 15 minutes the satellite transmits images that are being put together to film sequences in MeteoViewer.

Find out more about MeteoViewer in the teaching unit

 "Atmospheric Circulation".

 

 

MeteoViewer - Air Masses

Screenshot MeteoViewer - Luftmassen

In this version of the MeteoViewer, we encounter images with very unusual colour combinations. The offsetting and the combination of different infrared views of the European weather satellite Meteosat-9 (MSG) result in the development of images in which air masses can be distinguished based on their colour. Thus, subtropical, warm and humid air masses are green while polar, cold and dry air is depicted in different shades of blue. In taking a look at the moving images of the MeteoViewer, the development of lows or the position of the jet stream can be easily understood.

 

 

Image Calculators: Measuring and Calculating with Satellite Images

 

NDVI Calculator

Screenshot NDVI-Berechnung

The NDVI is an index indicating the vitality of vegetation on the surface of the earth by means of red and infrared wavelengths. In this example, the NDVI can be calculated from satellite images acquired before, during and after the 2007 Greek forest fires.

For further information on the function of the NDVI in remote sensing of vegetation click here or check out the teaching unit "Traces of Fire".

 

Image Difference Calculator

 

This tool serves to calculate the modification of two images of the same extract. In the emerging image, the modification is displayed in white. This example shows images of Las Vegas between 1975 and 2005. Aside from calculating them, you can also put the images on top of each other and you can compare them visually.
Find out more about the calculation of difference images in the teaching unit "Traces of Fire".

 

Image Classification: Creating Thematic Maps Online

RGB Classifier

RGB-Klassifikation

This tool makes it really easy to transform a satellite image into a thematic map. For this purpose, all sections of the satellite image similar in colour are marked with the help of three colour controllers (red, green and blue) and a tolerance controller. These sections can be coloured and linked to thematic information (e.g. water, forest or settlement) in order to create a map that features land-cover classes.

The unit "From Satellite Images to Maps" picks up on the RGB classification. If you want to find out more about colours and classification, we would like to encourage you to take a look at the info box.

 

Swipe: Layering Images and Detecting Change

Visual Image Comparison

This tool serves to visually compare satellite images. For this purpose, two satellite images are being put on top of each other and then compared by using the swipe tool. This is an excellent tool if you want to get an overview of changes that have taken place in a certain region. For further information on visual comparisons, their potential fields of application as well as the course of a tsunami, please check out the teaching unit "Tsunami".