Much of the disagreement between the outputs of the two methods occurs close to boundaries between different classes. 64 % of all the disagreement is represented in a buffer region of within 10 metres distance from boundaries between the different classes. 89 % of all disagreement is within 30 metres of these boundaries (Table 5). This suggests that boundaries are extremely important to understanding the dynamics of disagreement between classifications. It is worth noting that the differences in the class assignment are more likely to be due to interpretation inconsistency than due to the nature of the method employed. This comparison highlights one of the limitations of photography interpretation i.e. that an interpreter can be inconsistent with the interpretation if they repeat work in the same location. The main disadvantage in the point classification method is that areas where there are narrow strips of saltmarsh (which are thinner than the resolution of the point grid), may be missed in the analysis (e.g. in the Camel estuary). Table 6. The spatial relationship of inconsistency between the two classification methods and distance away from class boundaries. The border disagreement figure is the number of mismatched points within each of the buffer zones expressed as a percentage of the total number of mismatched points across the entire study area. The majority of the disagreement is within the 10 metre buffer zone. Buffer distance Border disagreement Accumulative border (m) (%) disagreement (%) 10 64 64 20 14 78 30 11 89 Remaining Points 11 100 Figure . a) the point classification and b) the manual digitization. This section of saltmarsh is relatively simple in structure with a coherent transition between Spartina, mid low marsh through to upper marsh.
Much of the disagreement between the outputs of the two methods occurs close to boundaries between different classes. 64 % of all the disagreement is represented in a buffer region of within 10 metres distance from boundaries between the different classes. 89 % of all disagreement is within 30 metres of these boundaries (Table 5). This suggests that boundaries are extremely important to understanding the dynamics of disagreement between classifications. It is worth noting that the differences in the class assignment are more likely to be due to interpretation inconsistency than due to the nature of the method employed. This comparison highlights one of the limitations of photography interpretation i.e. that an interpreter can be inconsistent with the interpretation if they repeat work in the same location. The main disadvantage in the point classification method is that areas where there are narrow strips of saltmarsh (which are thinner than the resolution of the point grid), may be missed in the analysis (e.g. in the Camel estuary). Table 6. The spatial relationship of inconsistency between the two classification methods and distance away from class boundaries. The border disagreement figure is the number of mismatched points within each of the buffer zones expressed as a percentage of the total number of mismatched points across the entire study area. The majority of the disagreement is within the 10 metre buffer zone. Buffer distance (m) Border disagreement (%) Accumulative border disagreement (%) 10 64 64 20 14 78 30 11 89 Remaining Points 11 100 Figure . a) the point classification and b) the manual digitization. This section of saltmarsh is relatively simple in structure with a coherent transition between Spartina, mid low marsh through to upper marsh.