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Questions tagged [reflectance]

Reflectance is the ratio of incident flux and reflected flux from a surface

13
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2answers
313 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 ...
8
votes
2answers
15k 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 ...
7
votes
1answer
1k 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 ...
7
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0answers
688 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/...
6
votes
1answer
4k 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 ...
5
votes
2answers
204 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 ...
5
votes
1answer
211 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. ...
4
votes
1answer
2k 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 ...
4
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1answer
1k 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 ...
4
votes
1answer
1k 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 ...
3
votes
2answers
338 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 ...
3
votes
1answer
6k 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?
3
votes
1answer
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 ...
3
votes
1answer
1k 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 ...
3
votes
1answer
575 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)...
3
votes
0answers
415 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 ...
2
votes
1answer
313 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), ...
2
votes
1answer
223 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. ...
2
votes
1answer
1k views

Sentinel-2 Reflectance calculation

which is the proceddure for reflectance calculation from Sentinel 2 1C products downloaded from ESA Scientific Hub?
2
votes
1answer
117 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 ...
2
votes
1answer
237 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 ...
2
votes
1answer
467 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 ...
2
votes
2answers
105 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 ...
2
votes
1answer
107 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 = ...
2
votes
1answer
93 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 ...
2
votes
1answer
91 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 ...
2
votes
3answers
260 views

Determining surface that reflectance curve matches?

I was wondering to what surface that reflectance curve belongs? It is definetely no water or snow since their reflectance drops at a much smaller wavelength. I was thinking about a dense cloud but ...
2
votes
1answer
959 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....
2
votes
0answers
38 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 ...
1
vote
1answer
500 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 ...
1
vote
1answer
90 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
1answer
476 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 ...
1
vote
1answer
188 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 ...
1
vote
1answer
982 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, ...
1
vote
0answers
54 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 ...
1
vote
0answers
97 views

view zenith angle of MODIS surface reflectance product and Landsat 8

I have a MODIS daily surface reflectance product (MYD09GA) which I'd like to validate Landsat 8 image with. I want to obtain pixels that only fall within the view zenith angle of Landsat 8 ( 0 - 7.5). ...
1
vote
0answers
47 views

GOCI Radiance to Reflectance

How can I convert a GOCI satellite image from Radiance to Reflectance? I have been searching through the internet, but most of them are related to other satellites. I try to calculate the reflectance ...
1
vote
0answers
66 views

Pre-processing in remote sensing [duplicate]

I have a bit of confusion on the pre-processing of remote sensed images. Do atmospheric correction methods such as Dark Object Subtraction convert the DN into reflectance values? If not, it is ...
0
votes
1answer
369 views

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

I downloaded calibrated/corrected Landsat 8 data (Level 2) from ESPA (https://espa.cr.usgs.gov/) to do land cover classification. But there are many corrections and calibrations can be done as listed ...
0
votes
1answer
108 views

A method to match narrow bands from in-situ spectrometer with Landsat-8 central band

Is there a way to resample Landsat-8 bands to match different bands from a spectrophotometer. I'm doing atmospheric correction, comparing in-situ reflectance measurements performed using 10-nm wide ...
0
votes
1answer
87 views

I can apply tasseled Cap transformation in surface reflectance (not ToA)?

I can not understand if I should adjust the Tasseled Cap index with the surface reflectance values or the Top of Atmosphere
0
votes
1answer
74 views

Obtain reflectance map in pix4d?

I can not obtain my reflectance map in pix4D. The program said: Unable to computed radiometric calibraticon from sequoia. Unable to computed coordinated system. Its rare, because normally i ...
0
votes
0answers
12 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(...
0
votes
1answer
22 views

Blank table when exporting a feature selection of a image collection

I'm trying to get reflectance data of some points that i've gotten from another database through a Json table of pings. I've used this code to get the data but returns only the title of columns with ...
0
votes
0answers
19 views

Is Sentinel-2A Band 8 (NIR band) has been affected by earth water vapor absorption feature?

I am starting working with S2A images. While looking at the bandwidth of S2A NIR band, it seems it has a wider area as Landsat-7 ETM+ NIR band. Previously I worked with L7 ETM+ NIR band and obtained ...
0
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0answers
44 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 ...
0
votes
0answers
23 views

How to Correct Landsat 8 Imagery with TOA Reflectance >1 and <0?

I recently downloaded Landsat 8 T1 imagery and have ran into some difficulties during pre-processing. I applied the TOA reflectance and sun elevation corrections to Bands 2,3,4,5,6 using ArcGIS's ...
0
votes
1answer
299 views

How do I convert Digital Number (DN) to reflectance in order to analyze NDVI

I'm working with a mapir nir + red camera meaning that its blue band captures nir light and its red captures red normally. I understand that NDVI is calculated using reflectance values. My question ...
0
votes
0answers
44 views

Why does ArcMap's Apparent Reflectance function call for Radiance Gain and Radiance Bias?

This documentation, as well as the function properties window, call for Radiance Gain and Bias to produce what ArcMap is calling "Apparent Reflectance" -- a term I am not otherwise familiar with. My ...
0
votes
1answer
195 views

Radiometric, reflectance and atmospheric correction for Landsat 8 image

I am struggling with the pre-processing process for landsat8 imagery. I want to use some indices (e.g. NDVI, SAVI, EVI, NDMI) and create a land cover map at the end using ENVI and ArcGIS. As a ...