The capability of satellite images, to use different spectral bands, gives the opportunity to combine selected bands and produce pseudocolor images that contain more information that that of a standard image, such type of vegetation, geological composition or land use.

In the example of image 1 that follows, the multispectral image of the area of Glyfada airport, shows the areas covered with fresh vegetation (such as grass) in deep red colour. This information cannot be seen in image 2 (panchromatic) even though the resolution is better.

The merging of images 1 and 2 (multispectral and panchromatic SPOT) combines the high resolution of the panchromatic image with the thematic content of the multispectral image, giving image 3.

Image 4 comes from Landsat and covers the visible area of spectrum. It is chromatically very close to the view from the altitude of 700 km above sea level. The thematic information contained in this image is less.

Orthophotos coming from aerial photographs have the unique characteristic of very high resolution. The resolution and color depth of such images depends solely upon shooting conditions such as flight altitude or camera and film used. An example of black & white orthophoto coming from the area of Halkidiki is shown below (image 5), following these thumbnails that show the level of detail accomplished.

5. Aerial (pixel: 1 x 1 m.)

Though quite more expensive to acquire compared to satellite images, this type of images provides the ultimate tool in digital photogrammetry.

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