Over the last decade there have been a number of developments in the precision and accessibility of satellite imagery. A number of internet firms including Google and Microsoft are able to offer public access to satellite images. Whilst this can be very useful and also very interesting, it does not mean that aerial photography is finished.
One of the reasons that aerial photography retains its popularity is due to its excellent resolution. With the advances in digital camera technology, aerial photography provides images of very high resolution whilst satellite resolution can be a bit limited by technology and also law. You might think that satellite images can be quite detailed but as yet, cannot compare with aerial imagery, which is approximately 5 times clearer. Satellite imagery resolution will improve as technology advances more detail will become apparent. This can be very useful in conservation areas where it can be difficult to gain access or where it would be preferred not to have humans go for fear of damaging delicate environmentsor ecosystems but where monitoring is necessary.
Another benefit of aerial photography over satellite imagery is the availability of images. Most commercial satellites are in orbit approximately 400 miles above sea level and circle the planet in a set pattern and retain a set speed. The satellite will pass over the same point on the planet once every 3 days. This means that it is not a very good method for capturing events particularly if there is cloud cover and if you think about it, the earth is covered in cloud approximately 60% of the time. Of course aerial photography is also subject to weather conditions however, if there is a break in the weather the plane can take off but can also fly below the cloud level and as such does not suffer the same limitations.
One of the limitations of satellite imagery is that the images are taken from above and although it is possible to take pictures from an oblique angle, it generally requires that the satellite camera has to be repositioned. This can be a costly and difficult manoeuvre and as such is only done when absolutely necessary. Aerial photography on the other hand is usually taken at an oblique angle and from one short flight, a number of images can be captured from different heights and from different sides. The time of day can be very influential as the sun will vary in strength and angle and also cast shadows.
There is no doubt that the technology for both satellite and aerial imagery will continue to evolve and develop. At the moment though, aerial photography remains a very useful tool if you require high resolution images from a variety of heights and angles.