I am working on using MODIS images to compare NDVI values from 2000-2020 in the Inner Mongolian region of China. I am using 500m resolution 16 day images from the terra MODIS downloaded from AppEEARS. I downloaded the images and used the "extract by mask" tool and batch option to extract an NDVI raster for each year for a particular watershed boundary. From there I used the raster calculator to multiply each raster by 0.0001 (the scale factor of NDVI). Next I used raster calculator again to subtract each year from the previous year and generate a number of rasters showing the change in NDVI between each year from 2000-2020 (for example there is a raster showing changes in NDVI between 2000 and 2001, and 2001 and 2002, etc.). The problem I am having is that there are no attribute tables associated with these rasters. I have tried using "copy raster" to change the pixel type from floating 32 bit to 32 bit signed, but it changes all NDVI values to 0 for the copied raster. Even if I use "build raster attribute table" on the copied raster with a 32 bit signed pixel type, an attribute table does not appear after the tool runs. I need to know the areas associated with each increase or decrease in order to quantify the area of the watershed that increased or decreased in NDVI each year.
Fantastic! I just tried this and it worked and produced a table. The table gives me the NDVI values and the count, which I am assuming is how many times they appear in the raster. Do you know if there is a way to also calculate how much area each NDVI value occupies?
One last question to make sure I am understanding.
If my raster cell size is 463.312716527777 (shown in attached image) and the count for a value of 1 is 606 (shown in attached image), I need to multiply the two numbers together and the area would be the product with units of meters squared?
