Data collection: Remote sensing factors

The following factors were selected in order to answer the question How good is the remote sensing data collection:

Remote technique

It is not practical to develop a ‘1 to 3’ scoring system to cover all possible techniques and combinations of techniques. A more pragmatic approach is to use your own judgement of whether the technique(s) used in the remote sensing survey were appropriate to distinguish between the expected ground types in the area.

Remote coverage

This score has two aspects: confidence in remote sensing data will be higher if the coverage is better (ideally overlapping data to provide ‘replicates’), and; confidence in remote sensing data from a homogenous area will be higher than if the area surveyed was heterogeneous. Therefore the MESH system takes account of both these aspects so that, for example, wider track spacing of AGDS is more acceptable for homogenous areas than for heterogeneous areas, which will require narrower track spacing to obtain the same confidence score.

Remote positioning

The positioning system is used here as a proxy for the precision of the positioning when collecting the remotely sensed data, because different systems will have different ranges of precision. The remote sensing data may have been collected using a different positioning system than was used to collect the ground truth data, so there is a score for Remote positioning and Ground truth positioning.

Remote standards applied

Following accepted standards during data collection gives an indication of the quality of the data. The standards used can be externally accepted (highest score), or internal to the organisation collecting the data (lower score). Data collected to internal standards score more highly than those which lack clear standards of data collection.

Remote vintage

The age (vintage) of the remote sensing data indicates the likelihood of change occurring on the seabed between the time the data were collected and the present day. It was not practical in this system to include an assessment of the environmental variability, including human impact, but it should be remembered that some habitats are temporally variable whereas others are static on a decadal time-scale (compare sand wave fields and bedrock outcrops). This issue is further complicated because a map may include both variable and static habitats.
The heterogeneity/coverage matrix above should be used to derive scores for Remote coverage.  First assess scores for each of the two components using the table on the left, and then find the appropriate overall Remote coverage score from the matrix on the right. Note that this separate heterogeneity/coverage process is a rough guide; the score is only one of many that will contribute to the overall score.

All material variously copyrighted by MESH project partners 2004-2010

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