How to calculate land surface temperture from Landsat8 imagery in Matlab?

38 views (last 30 days)
I have downloaded some Landsat 8 imagery and I want to calculate the LST (Land Surface Temperature) from these images in MATLAB.
However, something does not seem to go right. For example, when I checked the calculated temperatures over a glacier surface, the displayed values are more than 44 degrees Celcius. I don't think that this is possible, as a melting ice surface is of course not able to get positive higher than 0 degrees. Can anyone help me to check where things go wrong? I have not been able to find the error yet.
The code I have used can be found under the image. The formulas I used were found on: https://giscrack.com/how-to-calculate-land-surface-temperature-with-landsat-8-images/. I have uploaded the corresponding geotiff images at: https://drive.google.com/file/d/1CXxt7hHWNbXujt6rMQPgGw103Zo6vbIc/view?usp=sharing.
Thanks!
clear all
close all
B4 = double(imread('LC08_L2SP_194028_20210706_20210713_02_T1_SR_B4.tif'));
B5 = double(imread('LC08_L2SP_194028_20210706_20210713_02_T1_SR_B5.tif'));
B10 = double(imread('LC08_L2SP_194028_20210706_20210713_02_T1_ST_B10.tif'));
%%
% Search for metafile and extract parameters
directory = pwd; % Full path of the directory to be searched in
filesAndFolders = dir('*MTL.txt'); % Returns all the files and folders in the directory
metadata_file = filesAndFolders.name;
fid = fopen(metadata_file,'r');
text = textscan(fid,'%s','Delimiter','');
text = text{1};
% Band-specific multiplicative rescaling factor ML for band 10
idx = find(~cellfun('isempty',strfind(text,'RADIANCE_MULT_BAND_10')));
ML = string(text(idx));
ML = extractAfter(ML,"= ");
ML = str2double(ML);
% Band-specific additive rescaling factor AL from the metadata
idx = find(~cellfun('isempty',strfind(text,'RADIANCE_ADD_BAND_10')));
AL = string(text(idx));
AL = extractAfter(AL,"= ");
AL = str2double(AL);
% Band-specific thermal conversion constant from the metadata K1 from the metadata
idx = find(~cellfun('isempty',strfind(text,'K1_CONSTANT_BAND_10')));
K1 = string(text(idx));
K1 = extractAfter(K1,"= ");
K1 = str2double(K1);
% Band-specific thermal conversion constant from the metadata K1 from the metadata
idx = find(~cellfun('isempty',strfind(text,'K2_CONSTANT_BAND_10')));
K2 = string(text(idx));
K2 = extractAfter(K2,"= ");
K2 = str2double(K2);
clearvars idx fid metadata_file
%% Calculate TOA spectral radiance
% TOA = ML * Qcal + AL
%
% where
% ML = Band-specific multiplicative rescaling factor from the metadata (RADIANCE_MULT_BAND_x, where x is the band number).
% Qcal = corresponds to band 10
% AL = Band-specific additive rescaling factor from the metadata (RADIANCE_ADD_BAND_x, where x is the band number).
TOA = ML * B10 + AL;
%% TOA to Brightness Temperature conversion
% BT = (K2 / (ln (K1 / TOA) + 1)) - 273.15
%
% where
% K1 = Band-specific thermal conversion constant from the metadata (K1_CONSTANT_BAND_x, where x is the thermal band number).
% K2 = Band-specific thermal conversion constant from the metadata (K2_CONSTANT_BAND_x, where x is the thermal band number).
% TOA (Top of Atmospheric) spectral radiance.
BT = real(1321.0789 ./ log(774.8853./TOA +1.0)) - 273.15;
%% Calculate the NDVI
% NDVI = (Band 5 – Band 4) / (Band 5 + Band 4)
NDVI = (B5-B4)./(B5+B4);
%% Calculate the proportion of vegetation Pv
% Pv = ((NDVI – NDVImin) / (NDVImax – NDVImin))^2
% where
% NDVI is the Normalized Difference Vegetation Index
PV = ((NDVI - min(NDVI(:))) ./ (max(NDVI(:)) - min(NDVI(:)))).^2;
%% Calculate Emissivity E
% E = 0.004 * Pv + 0.986
% where
% Pv is the proportion of vegetation
E = (0.004 .* PV) + 0.986;
%% Calculate final Land Surface Temperature (LST)
% LST = (BT / (1 + (0.00115 * BT / 1.4388) * Ln(E)))
% where
% BT = Brightness Temperature
% E = Emissivity
LST = (BT ./ (1 + (0.00115 .* BT / 1.4388) .* log(E)));
LST(isnan(LST))=0;
%% Plot result
figure,
imagesc(LST),colorbar
caxis([0 80])

Answers (0)

Categories

Find more on Vector Fields in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by