Changes between Version 6 and Version 7 of Processing/atmosphericcorrection


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Timestamp:
Feb 22, 2017 1:42:50 PM (2 months ago)
Author:
mark1
Comment:

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  • Processing/atmosphericcorrection

    v6 v7  
    3535
    3636* Do not stand between the sun and the survey point - you will cast a shadow over the area. Ideally stand as far back as possible so as not to create erroneous reflections.
    37 * Measure level, homogeneous targets of greater size (5 - 10 times) than the resolution of the remote sensing data. In most cases this is not possible (even a square metre of concrete is not perfectly homogeneous) but try and find suitable targets. For example an expanse of car park may be suitable, a field of grass, a body of deep water. Surfaces that are not level will suffer greater from erroneous reflections (see bi-directional reflectance distribution fuinction (BRDF)). Remote sensing data will suffer from adjacency effects so the larger the target the better.
     37* Measure level, homogeneous targets of greater size (5 - 10 times) than the resolution of the remote sensing data. In most cases this is not possible (even a square metre of concrete is not perfectly homogeneous) but try and find suitable targets. For example an expanse of car park may be suitable, a field of grass, a body of deep water. Surfaces that are not level will suffer greater from erroneous reflections (see bi-directional reflectance distribution function (BRDF)). Remote sensing data will suffer from adjacency effects so the larger the target the better.
    3838* Make sure you collect more than one observation over the target to improve the measurement statistics (get as many as possible to calculate averages and standard deviations).
    3939* Try to measure near the centre of the targets rather than the edge where possible. For example, if you survey a car park do not observe near the boundary fence or hedge. If observing a water body remember the depth of the bottom will also affect the reflectance (e.g. the shallow boundaries will be different to the deep centre).