The data analysis methods used to obtain conclusions from field work practices include:
1. Analysis of the Truth of Interpretation
This analytical method is obtained from a field survey with a tool in the form of a suitability table. The table contains the point of interpretation location, survey location and coordinates. The survey points were taken based on the interpretation results which were considered less convincing so that it was necessary to carry out a field survey. Based on the table of the results of the field survey, it is expected that the accuracy value of the interpretation can be seen using the formula:
Correctness Level of Interpretation = (∑ Correct point / ∑ Surveyed Points) X 100%
Information on land cover classification from MODIS data shows that the classification results are said to be good if the accuracy is> 80% or the error is <20% when compared to conditions in the field (Kusumowigado, et al., 2007). The percentage of classification accuracy that is acceptable (or considered 'adequate') actually varies, depending on the type of survey used. Agronomists usually receive either yields greater than or equal to 90%, for crop classes. Meanwhile, geologists demand higher accuracy for rock type classification results because these classes recommend appropriate drilling locations, which are expensive (Danoedoro, 2012).
2. GIS Analysis of Image Interpretation Truth
After knowing the level of correctness of the interpretation of each class, then a supervised analysis is carried out, where the correct results of the interpretations are combined with the results of the unsupervised analysis.
3. Descriptive Analysis
This method is to explain and describe further the results of the analysis of the accuracy of interpretation and to explain the results of image overlay and research results in the field. With a descriptive method, changes in vegetation density and land cover forms that occur in the Solok City area can be described.