WebÞing

Browsing in a Scene

Every scene, including the global overview images, offers nearly 1000 Layers:

  1. The base image is based on an NDVI composite
  2. An "NDVI" lens filters the base image to greyshade (in case you find the colourmap unclear).
  3. Six Land Classification Layers
  4. Ten AVHRR composite layers for each of 93 ten-day periods

Use the Layers Menu to enable any of the AVHRR or Land Classification layers. When you enable a layer, it is loaded into a HyperLens® Lens. A new Lens button is installed in the panel at the left of the HyperLens® viewer. Click the button to open the Lens, and use the tabs on the Lens itself to move it around or resize it.

Browsing Data Quality

[AVHRR Browse Image]

The global AVHRR data are of variable quality. The HyperDAAC, offering a complete set of browse images at 32Km and 64Km, presents an ideal browse facility.

The image (left) shows a section of an AVHRR band in a lens covering most of South America. At the southern end, the black area indicates that no data are available. Also in the southern half of the image, the sharp diamond outlines suggest a problem with the data. The northern part of the image appears better. So if you are studying the Amazon you might consider using this image, but if you are interested in the Tierra del Fuego it is clearly of no use to you.

When you decide to retrieve a scene at higher resolution, use the comp10d lens to create a new scene, and then load the band you need into the scene.


See also