I am studying an area of diseased culture and I need to know the percent of the area where the index values corresponding to the diseased areas are manifested. Is it possible to perform this operation with pix4d?
Say you want the area of the map with index value between MIN and MAX.
You could use the Index calculator and divide the Index map into 2 classes of equal spacing (see https://support.pix4d.com/hc/en-us/articles/202560519#gsc.tab=0). For example if you are interested in the region of your field with index values between 0.15and 0.2 , we would suggest setting the min at 0.15, and the max at 0.25 (so that 0.15-0.20 will be one class). More generally, we would set the minimum to MIN, and the maximum to
MIN + 2* (MAX-MIN).
This way the two regions will be [MIN, MAX] and [MAX, 2*MAX-MIN]. The area of the region corresponding to [MIN, MAX] will be displayed, and this is what you are interested in. You can obtain the area of the full field at the top of the quality report for example.