How do you convert DN to reflectance in ENVI?
Click on the Reflectance radio button and enter an output file name. For ENVI Standard, select from the Toolbox | Radiometric Correction | Radiometric Calibration. Select the optical data file and the Radiometric Calibration dialog opens. Under Calibration Type choose Reflectance and save the new file.
What is Landsat surface reflectance?
Landsat Surface Reflectance measures the fraction of incoming solar radiation reflected from Earth’s surface to the Landsat sensor.
What is the difference between Landsat products TOA radiance and reflectance?
Radiance is the variable directly measured by remote sensing instruments. Basically, you can think of radiance as how much light the instrument “sees” from the object being observed. Reflectance is the ratio of the amount of light leaving a target to the amount of light striking the target. It has no units.
What is surface reflectance in remote sensing?
Surface reflectance (ρ) is defined as the fraction of incoming solar radiation that is reflected from Earth’s surface for specific incident or viewing cases (directional, conical, and hemispherical cases). From: Comprehensive Remote Sensing, 2018.
How do you calculate reflectance from DN value?
First compute Spectral radiance for kth band using formula: Radk = (DN*SRk)/1024. Here the SR denotes the Saturation Radiance.
How do you calculate reflectance value?
Reflectivity can be calculated as p(y) = Gr(y)/Gi(y) where p is the reflectivity, y is the wavelength of the light, Gr is the reflected radiation and Gi is the incident radiation. Calculate reflectance from the reflectivity. Reflectance is the square of the reflectivity so q(y) = (Gr(y)/Gi(y))^2.
How do you calculate surface reflectance?
What is the formula of DN?
N = bearing speed. This is the maximum amount of revolutions per minute (RPM) that the bearing will move. The DN factor of a bearing is obtained by multiplying the median diameter (A + B)/2 by RPM, and sometimes by a correction factor.
How many bands does Landsat 8 have?
nine spectral bands
Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) images consist of nine spectral bands with a spatial resolution of 30 meters for Bands 1 to 7 and 9.
How to convert Landsat OLI data to Toa reflectance?
Manually Converting Landsat 8 OLI data to ToA Reflectance: These data can be converted to ToA Reflectance using rescaling factors and parameters found in the metadata file (MTL.txt) provided with the data. The formulas and detailed explanations can be found on the USGS site: Using the USGS Landsat 8 Product .
How to compare Landsat 7 to Landsat 8?
If you want to compare for example Landsat 7 and Landsat 8 images, you would need to convert both to radiance or to reflectance, maybe do atmospheric correction, and still keep in mind, that even the spectral properties of the ETM+ and OLI corresponding bands are not exactly the same.
Why are eSun values used in Landsat 1-7?
The Collection data products for Landsat 1-7 are cross-calibrated to L8 OLI and provide two sets of scaling factors, one to calculate the TOA reflectance and the other to calculate TOA radiance, just as it has always been the case for L8 OLI. Thus, the ESUN values are not needed any more to do conversions between TOA radiance and TOA reflectance.
How is stray light correction applied to Landsat 8?
The stray light correction applied to Landsat 8 Collection 1 Level-1 data substantially improves image uniformity and absolute calibration in typical scenes. See Section A1 of the Landsat 8 Data Users Handbook for more details about Landsat 8 TIRS Stray Light.