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13 votes

What is the range of values of Sentinel-2 Level 2A images?

The Sentinel 2 L1C images started out as 12-bit, but that has been changed in early 2016 when ESA changed QUANTIFICATION_VALUE from 1000 to 10000. Now L1C is encoded as an UINT16 jp2 file with (at ...
mkadunc's user avatar
  • 2,071
11 votes

Difference between irradiance and radiance, remote sensing reflectance and water leaving radiance

I've found two sources that appear to provide easy to read explanation between Radiance vs. Irradiance and remote sensing reflectance and water leaving radiance. Starting with Radiance vs. Irradiance: ...
whyzar's user avatar
  • 12.1k
7 votes

Sentinel 2A L1C product convertion from TOA reflectance to BOA reflectance

You'll need to run ESA's Sen2Cor algorithm to process Sentinel-2 Level-1C data to Level-2A. This will give you atmospherically corrected BOA data. If you then divide the values by the quantification ...
Val's user avatar
  • 273
6 votes
Accepted

Sentinel-2 images color cast

Blue color cast is caused by atmospheric scattering (= light reflecting off particles in the atmosphere is added to the light reflected from the ground), and it is always present in top-of-atmosphere ...
mkadunc's user avatar
  • 2,071
5 votes

How to get property of each image in a collection in google earth engine?

If you want to add a calculated value as a new property to the image, then follow Kersten's advice, which is something along the lines of: collection_121_134 = collection_121_134.map(function(img) { ...
filups21's user avatar
  • 195
5 votes
Accepted

Are landsat 8 SR and TOA rasters calibrated/corrected data or the data to be used for calibration/correction?

You will want to use the *_sr_band1 to band7 data for your analyses as these are atmospherically corrected surface reflectance products (Figure 1). Only the Surface Reflectance data products and ...
Aaron's user avatar
  • 51.7k
5 votes
Accepted

What are the necessary correction/calibration on Landsat 8 imagery for land cover classification?

You can perform a land cover classification on a single Landsat scene without performing spectral and radiometric corrections. You will only need to do those corrections if you're trying to apply ...
Dan's user avatar
  • 1,100
5 votes
Accepted

Sentinel-2 Reflectance calculation

Sentinel 2 L1C product are top of atmosphere reflectances. It mean that ESA has already converted the raw DN (Digit Numbers) from the satellite MSI sensors into meaningfull physical values. This is a ...
radouxju's user avatar
  • 49.8k
5 votes

Converting DNs to radiance and reflectance for Planet Labs Imagery

If the file contains "DN" in the name then it is not scaled radiance and there is are no coefficients available to scale to scale to exo-atmospheric irradiance. If the product is the "analytic" ...
Frank Warmerdam's user avatar
4 votes

Strange reflectance values in Sentinel-2 images over sea ice

I quite disagree with you regarding the standard reflectance values of water in the near infrared (Band 8a). As water absorbs light in these wavelengths, these values should be very low (of course not ...
O. Hagolle's user avatar
4 votes
Accepted

WorldView 3 level OR2a processing - do I have data as DNs?

Yes - the regular OR2A data is delivered in Digital Numbers. If you want to test this, you could take a look at the values in your data - if all values you have are integers, chances are that you're ...
Mikkel Lydholm Rasmussen's user avatar
3 votes
Accepted

Landsat8 surface reflectance rescaling pixel

Is the second option. Data under 0 or over 10000 needs to be handled as NULL data (saturated cells). In your case, NULL Value is -9999, but if you set those ranges as a value instead of a NULL cell, ...
aldo_tapia's user avatar
  • 13.7k
3 votes

Strange reflectance values in Sentinel-2 images over sea ice

You are using the level 1C product (top of atmosphere reflectance), which will, in many cases, have atmospheric scattering present. Atmospheric scattering will skew the true surface reflectance value ...
Aaron's user avatar
  • 51.7k
3 votes
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Dark Object Subtraction using Top of Atmosphere Reflectance?

Dark object subtraction is not atmospheric correction. It is image normalization. It is the simplest way of making two images acquired at different times, with different atmospheric conditions and ...
Mikkel Lydholm Rasmussen's user avatar
3 votes

LiDAR returns over water bodies?

A far as I know, LiDAR signals do not get returned over water bodies. It depends which laser wavelength was used in the survey. If it was a wavelength near the infrared (> 700 nm) it should be ...
Andre Silva's user avatar
  • 10.3k
3 votes

How to apply a Bitmask for radiometric saturation QA in a image collection (earth engine)

Using radsat_qa require some bit manipulation. I usually copy and paste my little bitwiseExtract() function for these things. This should give you an idea how you can use it: function cloudMaskL457(...
Daniel Wiell's user avatar
  • 14.4k
3 votes
Accepted

NDVI out of range

If you first multiply every layer by 0.0001 and then calculate NDVI the surpassing shouldn't happen, as you are dividing a subtraction of two positive numbers (band values) by the addition of the same ...
Elio Diaz's user avatar
  • 3,486
3 votes
Accepted

Correcting Worldview-3 data to ground reflection/bottom of atmosphere with open source?

Converting WV3 data to ToA reflectance is fairly straight forward and is well documented in the official documentation. Basically, the approach is to go from DN to ToA radiance (L), using this formula:...
Mikkel Lydholm Rasmussen's user avatar
3 votes

Google Earth Engine and Sentinel-2 L2A processing update

The harmonized sentinel-2 L2A collection is already on GEE now: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_SR_HARMONIZED
smile4lee's user avatar
2 votes

NDVI analysis of LANDSAT 8 imagery in QGIS

Using Dark Object Subtraction (DOS) can provide a a quick way to correct for atmospheric effects, which may be sufficient for preparing multispectral data for spectral indices such as NDVI. However, ...
ahmadhanb's user avatar
  • 41.1k
2 votes
Accepted

Radiance to reflectance error ArcMap

Remove the square brackets [] from your expression. The tutorial uses an old version of ArcGIS that has slightly different raster calculator syntax.
user2856's user avatar
  • 67.3k
2 votes
Accepted

Landsat level-2 data comparison

Yes, you do need to correct Landsat 8 imagery to compare it against Landsat 5 and 7. The data between the three satellites are not directly comparable in their raw form. This paper compares Landsat 7 ...
user5858's user avatar
  • 405
2 votes
Accepted

Surface reflectance product - do I always need it?

Since you just want to delineate the borders between two land uses you don't need to worry about using images with atmospheric correction. In case your application really needs the surface values (for ...
GCGM's user avatar
  • 1,118
2 votes

Negative values in Landsat 8 surface reflectance higher level product

Check product guide from Landsat 8 surface reflectance. Values range is from -2000 to 16000, but the valid range is from 0 to 10000, so you need to mask off pixels out of range. In R you can change ...
aldo_tapia's user avatar
  • 13.7k
2 votes

Convert Planet Imagery Surface Reflectance product DN to surface reflectance values

The SR product is provided as a 16-bit GeoTIFF image with reflectance values scaled by 10,000. There is also a tutorial tutorial to convert MS radiance to reflectance.
mmann1123's user avatar
  • 591
2 votes

Converting Landsat8 DN to TOA reflectance using GEE manually

May I ask, why are you going about it this way instead of using the built-in function for this purpose: ee.Algorithms.Landsat.TOA(input) ? Have a look at the documentation, but I suspect this might be ...
Pictory's user avatar
  • 194
2 votes

Filter Landsat 5 Surface Reflectance Images by Cloud Cover with a Region of Interest in GEE

You have to map a reduceRegion over the collection to compute a cloud score for your ROI, store than on each image, then sort/filter on that value. You can compute the cloud score by just counting ...
Noel Gorelick's user avatar
2 votes
Accepted

Getting reflectance from Sentinel2 L2A images

You are right. If you have any doubt please read the Sentinel-2 L2A Product Format Specification document: https://sentinel.esa.int/documents/247904/685211/Sentinel-2-MSI-L2A-Product-Format-...
sermomon's user avatar
  • 994
2 votes
Accepted

Why the result of download for Sentinel-2 Cloud Removal doesn't show reflectance value?

I think the scale factor is missing. According to the documentation, a scale 0.0001 needs to be applied. From this segment of the tutorial, it is clear that the scale factor is not applied. The ...
Padmanabha's user avatar
  • 1,402
1 vote
Accepted

Negative Surface Reflectance

You already have surface reflectance, not DN. You are trying to apply the level 1 TOA reflectance correction to already corrected level 2 data. Just apply the scale factor of 0.0001 to convert the ...
user2856's user avatar
  • 67.3k

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