Questions tagged [reflectance]
Reflectance is the ratio of incident flux and reflected flux from a surface
84 questions
14
votes
1
answer
7k
views
What is the range of values of Sentinel-2 Level 2A images?
I found in Level 2A Product Format Specifications Technical Note page29 that:
"The L2A Quantification Value is aligned with the L1C Quantification Value of the L1C product from which the L2A product ...
- 141
12
votes
2
answers
533
views
Ice type differentiation using satellite data
I would like to classify glacial area by categories of snow (if there is) and ice, but what's most important: between old ice and fresh ice. They have different properties that are possible to ...
- 739
10
votes
2
answers
26k
views
Difference between irradiance and radiance, remote sensing reflectance and water leaving radiance
I've been trying to lay my hands on textbooks, etc, that explain the differences between the remote sensing terms in lay man language.
radiance and irradiance
remote sensing reflectance and water ...
- 507
10
votes
1
answer
1k
views
Landsat level-2 data comparison
I'm doing a temporal analysis of NDVI and temperature over 17 years, necessitating data from Landsat 5,7, & 8. I'm interested in using level-2 Landsat data available from https://espa.cr.usgs.gov/...
- 425
8
votes
1
answer
6k
views
Radiometric calibration of Sentinel-2 products
How can I calibrate Sentinel-2 products, to extract the reflectance?
I've downloaded few Sentinel-2 products from https://scihub.copernicus.eu/s2/#/home, and opened them with SNAP but its radiometric ...
- 956
6
votes
2
answers
431
views
Sentinel-2 images color cast
I work with Sentinel-2 images (Level-1C products (top-of-atmosphere reflectances)). I would like to know why some of the images do have this blue(?) undertone/color cast. I think those images are from ...
- 103
6
votes
1
answer
3k
views
LiDAR returns over water bodies?
I have obtained LiDAR data from my environmental agency in order to obtain the relative heights of each watercourse station. A far as I know, LiDAR signals do not get returned over water bodies. ...
- 10.3k
5
votes
1
answer
8k
views
Sentinel 2A L1C product convertion from TOA reflectance to BOA reflectance
How can I convert the TOA reflectance values of L1C Sentinel2A products to BOA (Bottom Of Atmosphere) reflectance values?
Is there an equation?
5
votes
2
answers
2k
views
Dark Object Subtraction using Top of Atmosphere Reflectance?
I'm working on a WorldView 3 image in QGIS and have been told to use Dark Object Subtraction (DOS) to atmospherically correct it to surface reflectance using the raster calculator. I have the Top of ...
- 341
4
votes
1
answer
3k
views
Is the reflectance required to get the NDVI, for Landsat 8 images?
I'm a beginner in satellite optical imagery.
I have a landsat 8 image (11 bands downloaded from http://earthexplorer.usgs.gov/) for which I need to calculate the NDVI (Normalized Difference Vegetation ...
- 956
4
votes
1
answer
1k
views
WorldView 3 level OR2a processing - do I have data as DNs?
I have a World View 3 image which is level Ortho Ready Standard Imagery
(OR2A) processed and I wish to ascertain what this processing level means.
I need to work on surface reflectance and am aware ...
- 341
4
votes
1
answer
2k
views
Convert Planet Imagery Surface Reflectance product DN to surface reflectance values
I have a PlanetScope Ortho Scene Product (3B) which includes an AnalyticMS.tif and AnalyticMS_SR.tif files. Based on what I have read so far, the AnalyticMS_SR.tif file is scaled surface reflectance ...
- 51
4
votes
1
answer
2k
views
Differences between mWm-2sr-1(cm-1)-1 and W/m^2 * sr * um
I'm confused about the use of this quantity. For example eumetsat
on pag. 16 radiance is equal to:
Physical Units = Cal_Offset + (Cal_Slope x Level 1.5 Pixel Count)
expressed in mWm-2 sr-1 (cm-1)...
- 327
3
votes
2
answers
498
views
Strange reflectance values in Sentinel-2 images over sea ice
I am dealing with Sentinel-2 (Level 1C) images over sea ice. I have downloaded some and was wondering: When I look e.g. at Band 8A, there are some images where the reflectance over the water between ...
- 31
3
votes
1
answer
7k
views
How to get property of each image in a collection in google earth engine?
I am trying to convert ASTER image from DN values to reflectance. For this I require gain coefficient of each image in the collection I have gathered.
//Defining geometry
var geometry = ee.Geometry....
- 31
3
votes
1
answer
2k
views
Converting DNs to radiance and reflectance for Planet Labs Imagery
I am trying to convert pixel DNs to reflectance from a Planet BGRN Analytic Scene (from 2016, I can't tell what level it is processed to). However, I can't find info on the exo-atmospheric irradiance ...
- 31
3
votes
1
answer
477
views
Landsat8 surface reflectance rescaling pixel
Sorry for this basic question, but I am using Landsat8 images with "surface reflectance" treatment from Landsat8.
I am having some trouble with the data from some bands. Most of pixel are beyond 10k.
...
3
votes
1
answer
2k
views
NDVI analysis of LANDSAT 8 imagery in QGIS
I am trying to run an NDVI classification of 2015 multispectral LT8 imagery in QGIS to assess the quality of vegetation cover in regards to habitat suitability for a primate species in northern ...
- 123
3
votes
1
answer
2k
views
Converting Worldview 2 imagery to TOA reflectance for Vegetation Change detection in ArcGIS?
I am working on a change detection study to look at effects of herbicides on vegetation growth. Therefore I have Worldview 2 (4 band +pan band) imagery for two subsequent years that I would like to ...
- 31
3
votes
0
answers
636
views
Negative reflectance values after topographic corrections (cosine correction and modified Minnaert correction)
I am trying to manually correct the surface reflectance values of some Landsat 7 and 8 images. I'm using Minnaert modified method, which uses the cosine correction as one of its inputs (see below the ...
- 71
2
votes
1
answer
1k
views
Are landsat 8 SR and TOA rasters calibrated/corrected data or the data to be used for calibration/correction?
I downloaded Landsat 8 Level-2 scenes from https://espa.cr.usgs.gov/ for land cover classification. Following are the product list in the package, cause I ticked Top of Atmosphere Reflectance (TOA), ...
- 315
2
votes
1
answer
3k
views
Sentinel-2 Reflectance calculation
What is the procedure for reflectance calculation from Sentinel 2 1C products downloaded from ESA Scientific Hub?
- 483
2
votes
2
answers
842
views
Google Earth Engine and Sentinel-2 L2A processing update
As of 25-January-2022 ESA has updated its processing baseline for Sentinel-2
Therefore, Sentinel-2 L2A Bottom of Atmosphere (BOA) reflectance (L2A_BOA) should be retrieved using L2A_BOAi = (L2A_DNi + ...
- 1,879
2
votes
1
answer
204
views
NDVI out of range
I have composed a mosaics of 3 images of Landsat 8 Surface Reflectance Level 2 for the bands NIR and RED. According to the Landsat Surface Reflectance Product Guide each band is supposed to be ...
- 413
2
votes
1
answer
828
views
Filter Landsat 5 Surface Reflectance Images by Cloud Cover with a Region of Interest in GEE
I'd like to filter a large collection of Landsat 5 Surface Reflectance images by cloud cover within a small region of interest (not the entire image scene) in Google Earth Engine. I know there are ...
- 21
2
votes
2
answers
2k
views
Landsat 8 - Reflectance Values
I downloaded some Landsat 8 OLI/TIRS C1 Level-1 images from EarthExplorer. I was hoping to get reflectance data out of the blue, green and red band; however, when I opened those images in ArcMap, the ...
- 339
2
votes
1
answer
228
views
Surface reflectance product - do I always need it?
There is a neat Surface Reflectance product of Landsat imagery. I know the difference between SR and raw products: SR presents calculated values, that are supposed to represent state of the Earth ...
- 739
2
votes
1
answer
518
views
Explanation on band conversion from radiance to reflectance final value
I've watched few video on conversion of radiance to reflectance for landsat band, most of them recommended to use formula below to to make sure the final reflectance value lies in between 0 to 1. My ...
- 31
2
votes
1
answer
396
views
Negative Surface Reflectance
I am using Landsat Surface Reflectance Level-2 images. I have to convert the DNs to reflectance values. When I apply the formula provided in the Landsat8 User Handbook :
reflectance = ...
- 123
2
votes
1
answer
141
views
Very low reflectance values landsat 7
I am getting very low reflectance values (mostly < 0.15) in all bands of multiple Landsat 7 scenes after having converted to TOA reflectance manually in ENVI. These values are not supposed to ...
- 103
2
votes
1
answer
365
views
Landsat 8 reflectance values very low
I am getting very low reflectance values (mostly < 0.1) in Landsat 8 bands 2-7 on different scenes after rescaling from Digital Numbers (DN) to Reflectance. All scenes are in a tropical landscape ...
- 63
2
votes
1
answer
215
views
Automatic conversion to surface reflectance (SCP)
I am practicing for SCP part by using Qgis 2.10.1.
I already download desired LANDSAT image from SCP>Download Landsat.
However, in Pre-processing part, after click Select directory button, the ...
- 79
2
votes
0
answers
99
views
Viewing Angle Effect On Spectral Reflectance Sentinel-2
I am new to remote sensing and would like resources and literature explaining the effect of viewing angle on spectral reflectance for satellites. I have read the study by Moriya et al translated to ...
- 53
2
votes
1
answer
1k
views
PlanetScope NDWI calculations
I am trying to calculate NDWI for a PlanetScope image scene. I currently have 2 products: one is the "3B_AnalyticMS_SR.tif" and the other is the "3B_AnalyticMS.tif" product. I ...
- 29
2
votes
0
answers
194
views
Calculating Reflectance from Parrot Sequoia DN
I am dealing with the images of a Parrot Sequoia. I could not pre-process the images in Pix4d because I took single shots in different parts (so there are not overlapping images).. for me it is ...
- 21
2
votes
0
answers
197
views
When to rescale reflectance data to calculate vegetation indices
I'm attempting to calculate a number of vegetation indices using hyperspectral AVIRIS data in ENVI. Some of these indices are normalized, such as NDVI, whereas others are not, such as the Transformed ...
- 425
2
votes
0
answers
58
views
eCognition - prevent rounding of raster values?
I have a WorldView2 image, which I would like to segment and classify in eCognition. The image has been pre-processed to Top of the Atmosphere Reflectance, therefore hasvalues between 0-1.
The ...
- 73
1
vote
2
answers
1k
views
How to apply a Bitmask for radiometric saturation QA in a image collection (earth engine)
I am new to earth engine and I am trying to apply a radiometric saturation mask in a image collection based on ''radsat_qa'' in earth engine data catalog for landsat reflectance tier 1.
I am trying ...
- 81
1
vote
2
answers
871
views
Correcting Worldview-3 data to ground reflection/bottom of atmosphere with open source? [closed]
I have some worldview-3 imagery that needs to be corrected from digital numbers to actual reflection values (preferably bottom-of-atmosphere). But the tricky part is I am looking for open source ...
- 543
1
vote
1
answer
72
views
Why the result of download for Sentinel-2 Cloud Removal doesn't show reflectance value?
I succeed to remove cloud from these step in :
https://developers.google.com/earth-engine/tutorials/community/sentinel-2-s2cloudless
Then I download the result. But, the result is not in decimal as ...
- 303
1
vote
1
answer
479
views
Getting reflectance from Sentinel2 L2A images
I want to get surface reflectance at some points on GEE for Sentinel2 L2A images. I know that I can use inspector to get band values at each point. I read that these values are Digital Numbers and ...
- 115
1
vote
1
answer
757
views
Converting Landsat8 DN to TOA reflectance using GEE manually
I'm fairly new in Google Earth Engine and JavaScript. I'm trying to convert Landsat8 DN to TOA reflectance using GEE using a function.
// Load a raw Landsat scene and display it.
var image = ee.Image(...
1
vote
2
answers
256
views
Why reflectance map in pix4d dont are normalized
I want to know, why my reflectance map, dont have value between 0 and 1. Because my calibration table said me: for example red band has max value = 0.88 nm, and my reflectance map in red band have max ...
- 117
1
vote
1
answer
1k
views
Negative values in Landsat 8 surface reflectance higher level product
I have downloaded Landsat 8 higher level surface reflectance product from USGS to genetare chlorophyll map in lake. But the individual bands contain some negative surface reflectance values. So, when ...
- 75
1
vote
1
answer
118
views
Radiance to reflectance error ArcMap
I have been trying and failing for some time to convert the radiance to refectance by following step 4 in this tutorial
I have tried everything I can think of but my knowledge is limited. Would ...
1
vote
1
answer
688
views
Landsat 8 reflectance calibration
I am calibrating my landsat data to reflectance with correction for sun angle. I just want to know if sun angle is computed as such θsin(sun_elev), where sun_elev is the sun elevation value specified ...
- 371
1
vote
1
answer
1k
views
Calculating blue sky albedo with MODIS & Google Earth Engine
I am trying to calculate the blue sky albedo, which I think is the same as land surface albedo, using Google Earth Engine and the 'MCD43A3.006 MODIS Albedo Daily 500m' data.
I've managed to find ...
- 11
1
vote
1
answer
247
views
Understand values for Landsat 8 surface reflectance image
What do the numbers represent when you download an image, in my case Landsat 8 OLI TIRS surface reflectance.
Are they DN numbers or reflectance values?
If the image is not surface reflectance product, ...
- 1,065
1
vote
1
answer
287
views
Landsat 7 - 8 surface reflectance bands from ESPA (LEDAPS)
I have downloaded some Level 1 and higher level imagery data including surface reflectance as well.
I should process these data in Idrisi (Selva) package.
The Level 1 images' pixel values are between ...
- 11
1
vote
1
answer
2k
views
Calculating Albedo for Landsat 8 using QGIS with GRASS?
I am trying to estimate albedo for Landsat 8 OLI. The idea was to use the GRASS function i.albedo within the processing toolbox of QGIS. However, the option for Landsat 8 OLI is not available, ...
