Landsat has an average resolution of 30m, so it is common to associate the area of ​​a pixel to 900 m². But, since the original MapBiomas data is created following the GEE standard representation (Lat/Long and WGS84), it does not use a native equal-area projection. Thus, the distance from the target to the Equator Line influences the pixel size. Therefore, in the continental scale of Brazil area calculation counting the pixels and multiplying by 900 m² should be avoided. In MapBiomas we apply two methods for area calculation.

(i) When performed outside Google Earth Engine, we reproject MapBiomas data to the UTM system and calculate the metric value of the central pixel, located at the intersection between the 1: 250,000 (IBGE standard) chart and area of ​​interest. Next, we count all pixels within the area of ​​interest and multiply by the reference value, in m², as previously calculated. This method has been applied, for example, throughout all the statistics calculation in Collections 2 and 2.3.

(ii) When the calculation is performed within Google Earth Engine we apply the function ee.Image.pixelArea() that generates an image in which the value of each pixel is the area of that pixel in square meters, taking into consideration eventual cartographic distortions. This method is being applied from Collection 3.