[Aust-NZ] How Does Satellite Imagery Compare with Aerial Photography? [SEC=UNCLASSIFIED]

[Bruce Bannerman]

Resolution is only part of the story.

A major advantage that you have with typical remotely sensed imagery such as satellite imagery is that the sensor used often captures many spectral bands of data.

This allows for many options to digitally analyse the imagery pixel by pixel using a wide range of techniques. This can be used for a wide range of uses: e.g. masking out areas of water; finding vegetation that is subject to infestation by a particular 'bug'; measuring the 'green-ness' of vegetation; finding all areas on an image that have a similar spectral response to a particular 'training area'; etc.

With aerial photography, you are typically restricted to just three spectral bands (red, green and blue), though near infra red is sometimes used to check vegetation health.


Bruce



________________________________________
From: aust-nz-bounces at lists.osgeo.org [aust-nz-bounces at lists.osgeo.org] On Behalf Of John Smith [deltafoxtrot256 at gmail.com]
Sent: Tuesday, 6 April 2010 7:12 PM
To: Ross Charles Johnson
Cc: aust-nz at lists.osgeo.org
Subject: Re: [Aust-NZ] How Does Satellite Imagery Compare with Aerial   Photography?

On 6 April 2010 18:50, Ross Charles Johnson <rossgo at hotmail.com> wrote:
>
> A comparison of satellite imagery with aerial photogrammetry today must take
> into account advances in both approaches to the production of useful
> landscape and earth observation data today. Whereas most debate previously
> surrounded issues related to resolution and accuracy, the costs of
> purchasing satellite imagery have dropped substantially and satellites
> revisit the same location weekly or daily in some cases.

While there has been technical improvements, the US government has
resolution limitations on sat imagery provided commercially of 50cm
per pixel although GeoEye-1 has claims about the highest sat imagery
available at 41cm but only US govt agencies can access that.

Based on what I've seen from Nearmap, I haven't seen any restrictions
on the resolution of aerial photography in Australia and they've
produced 7.5cm for most areas of coverage and down to 3cm in select
areas.

http://en.wikipedia.org/wiki/GeoEye-1#Specifications_and_operation
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