![]() ![]() Corrections also must be applied to remove atmospheric effects and haze. Cloud free coverage, especially in the tropics, can be very difficult to obtain. An image is considered valid if cloud cover is less than 10-15%. Due to low altitude acquisition, aerial data does not suffer from atmospheric effects which can impact the quality of data in satellite imagery.Īpart from SAR (synthetic aperture radar) satellites which can acquire data regardless of cloud cover and illumination conditions, most satellite providers do not guarantee completely cloud-free imagery. This guarantees cloud-free data delivery. ![]() It is also possible to fly under cloud cover with minor corrections to be applied during post-processing. Stereo imagery is usually not included in satellite image capture and the generation of other value-added products usually relies on external data sources.Ī big advantage of using aerial imagery is the flexibility to plan data acquisition according to the local weather conditions and take every opportunity to fly in cloud-free conditions. However, newly launched high resolution satellites possess additional optical bands designed for specific applications such as vegetation analysis. The range of data available from earth observation satellites is increasing but non-standard sensors still suffer from lower resolution and high capture costs. This enables a wide range of value-added products to be generated to a high degree of accuracy including Digital Elevation Models (DEMs), Digital Surface Models (DSMs), contours, orthophotos and 3D GIS feature data capture. Normal aerial surveys are captured with full stereo mapping capability (60-80% forward overlap between images), and 30% side overlap between runs. Most aerial cameras offer a fourth near-infra-red band of imagery as well as standard RGB bands. It is important to note that very high-resolution satellite imagery falls in the mid to low end range of digital aerial imagery resolutions.Īerial acquisition aircraft offer the flexibility of being fitted with a wide range of sensors such as multispectral, hyperspectral, thermal, and other survey sensors. ![]() Restrictions apply for civil use and 30 cm is currently the highest commercially available resolution. Most new earth observation satellites can now capture images at sub-metre resolution. The large format aerial cameras can capture larger frames which ensures that less runs are needed to map an area. Most of the aerial imagery demanded by commercial organisations ranges between 10-15 cm and can go up to as high as 2.5 cm depending on application. With the development of large format digital aerial cameras, it is possible to capture via aerial platforms, a large project area with extremely high resolutions, suitable for engineering surveys and similar projects. A 2.5cm aerial image captured over Adelaide, Australia Without going into the detail of specific sensors, we present some of the main parameters to consider when making a choice between high resolution satellite or aerial imagery. Both aerial imagery as well as satellite imagery possess unique characteristics and strengths which are highlighted in this article. It is important to make an informed decision about which technology to choose for a project requiring spatial data after considering all aspects of your requirement. These technologies can even overlap in terms of resolution, meaning that other factors such as accuracy, acquisition and processing time need to be considered. The gap however between these two usually complementary mapping technologies is getting smaller as both satellite and aerial imaging systems have benefited from great technological improvements over the years. While both technologies can produce digital imagery, aerial imagery is largely used across commercial applications, and satellite imagery for large-scale scientific applications. They can both be used for a range of applications wherein geospatial data is required. Aerial Imagery and Satellite imagery both offer users a view of the ground and its features, objects from above. ![]()
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