Sydney Storm Fly Over, page-43

High Resolution Digital Aerial Imagery vs High Resolution Satellite Imagery

***  Resolution

Aerial Imagery:

With the development of new generation large format digital aerial cameras, it is possible to capture a project area with resolution up to 25mm (2.5cm), suitable for engineering survey type projects. Despite the fact that very large amount of data has to be acquired, large format aerial cameras can capture larger frames than ever before which implies less runs are needed to map an area. Aerial imagery resolution typically ranges from 90cm at the coarse end up to an impressive 2.5cm with a large demand in the range 15cm to 10cm.

Satellite Imagery:

Most of new earth observation satellites can now capture images at sub-metre resolution. Restrictions apply for civil use and 50cm is usually the highest resolution available. Efforts are being made to decrease this limit to 30cm in the coming years but physical and technology limitations will keep satellite resolution around 30cm.

It is important to note that “very high-resolution” satellite imagery falls in the mid to low end range of digital aerial imagery resolutions.

*** Location accuracy

Aerial Imagery:

With improved quality of large-format digital aerial cameras, airborne GPS and post-processing techniques, the absolute accuracy of aerial imagery is getting better and better. A typical horizontal accuracy of two pixels can be expected for aerial imagery. 3D features and DEM data can be determined to an accuracy of approximately one pixel in height.

Satellite Imagery:

High resolution satellites location accuracy is usually around 10m to 20m without ground control points but this value is improving with new satellites coming up. With a network of GCPs the accuracy can be improved to a few metres.


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