Hello everyone, I processed a sentinel-2 image using sen2cor, and then resampled the image to .BEAM-DIMAP. However, when I extracted pixel values by pins, I got the following pixel values:
The band values looks abnormal. So I processed one more image of another date, the band values looks better:
My question is: are the band values wrong? If the band values are wrong, how can I get the right ones?
The first suggestion in this case is , reprocess once more the same image and see if it’ll has the same result,
the question is,
Does this image has any cloud cover?
IF the image of this date, has no cloud cover and after reprocessing, it’ll give you similar results, in this case, check the ground cover, if any change has occurred comparison to the other date.
Thank you for your reply and suggestion!
Actually, I have processed the same image many times, and I even processed the image by ENVI 5.3, but unfortunately, the results are the same.
20181116 has no cloud cover. 20190609 has some cloud, but our study site is not covered.
Our suty site is a 0.6 km2 lake, so I don’t think the change between the two dates should be that big.
Would you please to clarify which date has “abnormal results” as you have mentioned!
I am sorry, it’s 20181116. The full file name of the image is “S2A_MSIL1C_20181116T030001_N0207_R032_T50SNJ_20181116T055625”.
My suggestion in this case to be sure from the reason of these values is, Select closer date to this one “20181116” to be during winter as well same year, and process it, in case it gives similar result to this one, this might be reasoned to the level of water, is much higher than the level of water, the image during summer, in the summer case water turbidity is more resulted from water evaporation which leads to increase the reflectance , also the speed of the wind and the degree of the illumination by sun as the main source of the light is different.
I found this might be it helpful, The drying-up of Lake Aculeo
Source : https://sentinels.copernicus.eu/web/sentinel/news/-/article/copernicus-sentinel-2-improves-observations-of-lakes-and-water-bodies
Also be aware that the water reflectance’s values are located in this part of the diagram,
OK, Thank you very much again! I’m going to have a try and show you the results.
I processed 2 more images, 20181007 and 20181206, the other images of closer date are covered by cloud. Here are the results:
Both of the 2 images has very low pixel values, so I think the images are normal, and the pixel values are just like that.
Thank you very much!