How do you convert radiance to reflectance?
It is possible to manually convert these DNs to ToA Reflectance using a two-step process. The first step is to convert the DNs to radiance values using the bias and gain values specific to the individual scene you are working with. The second step converts the radiance data to ToA reflectance.
What is ASTER imagery used for?
Scientists use ASTER data to create detailed maps of land surface temperature, emissivity, reflectance, and elevation.
How do I download ASTER photos?
Go to https://earthdata.nasa.gov/ and type ASTER in the search window. You should be able to get all the ASTER data products held in the NASA Land Processes Distributed Active Archive Center which is located at the EROS Center, Sioux Falls, South Dakota, which is a USGS facility. The data are available at no charge.
Where can I download ASTER Data?
ASTER data are are available from several archives:
- Earthdata Search – Search the entire ASTER data archive.
- GLoVis – Search the entire ASTER data archive using a browse-based map interface.
- ASTER/AIST – You can search the entire ASTER data archive using a browse-based map interface.
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.
What is the difference between 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.
What is ASTER in remote sensing?
The ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor is an imaging instrument flown on the Terra satellite which was launched in December 1999. An ASTER scene covers an area of approximately 60 km by 60 km and data is acquired simultaneously at three resolutions.
What is the spatial resolution of ASTER?
15m
ASTER Satellite Sensor Specifications
| Instrument | VNIR | TIR |
|---|---|---|
| Spatial Resolution | 15m | 90m |
| Swath Width | 60km | 60km |
| Cross Track Pointing | ± 318km (± 24 deg) | ± 116km (± 8.55 deg) |
| Quantisation (bits) | 8 | 12 |
How do you get ASTER DEM?
- Search for ASTER GDEM at the top left.
- Pick the area.
- Get the list of URLs you want, and save as a text file.
- You will need a NASA account, and be logged in on your browser to do the downloads (the browser will prompt you to log in for the first download).
What is ASTER Database?
Aster SQL-GR is a Graph processing engine for performing Graph analytics on big data sets in the Aster Database. Graph discovery enables users to analyze complex Graph network structures. The Visualization module includes several capabilities that use Visual SQL-MapReduce functions.
Is ASTER imagery free?
Credits: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Beginning 1st April 2016, all Earth imagery from the Japanese remote sensing instrument operating aboard NASA’s Terra spacecraft since late 1999 is available to users everywhere at no cost.
How do you convert transmittance to reflectance?
When you think about reflectance in this way, converting between transmittance and reflectance is rather simple. The transmittance (through the coating/interface) is simply T = 1-R.