*2.4. Land-Use Mapping and Validation*

We adopted the ISODATA-based (Iterative Self-Organized Data analysis) unsupervised classification approach for mapping the three major land-use types, built-up area, water body, and vegetation cover, which are prevalent in inner Hanoi City. We carried out tasseled cap transformation for the Landsat 8 OLI images, and calculated three tasseled cap indices, Greenness, Wetness, and Brightness, following the methodology and transformation coefficients (Table 2) provided by Baig et al. [32].

These three tasseled cap indices were used for ISODATA-based clustering and unsupervised mapping of the land-use types for the years 2016 and 2017. Four main land-use types, including built-up, vegetation, water, and others (others mean that the pixels (regions) are mixed with built-up, vegetation, and water) were mapped. For validation, we made a common map (changed and un-changed areas) between 1 June 2016 and 4 July 2017, including four classes: built-up, vegetation, water, and others & changes. The changed areas are not stable pixels (and also needed to be checked). We chose 100 geo-location points belonging to the un-changed area of each class (built-up, Vegetation, and water) plus the others & changes areas, to validate the classification results. A total of 300 points (for three target classes) were selected. The random points were checked through visual interpretation of Google Earth images and Google Map, acquired in June 2016 and August 2017, respectively. The distribution of the chosen points is displayed in Figure 2.

**Figure 2.** Distribution of the ground truth points on a common area map chosen in the research.


**Table 2.** Tasseled cap transformation coefficients for Landsat 8 at-satellite reflectance of six bands: Blue, Green, red, near-infrared (NIR), shortwave infrared (SWIR 1), and shortwave infrared (SWIR 2) (adopted from Baig et al. [32]).
