# 3.4.3.1. ASTER¶

ASTER

This tab allows for the conversion of ASTER L1T images to the physical measure of Top Of Atmosphere reflectance (TOA), or the application of a simple atmospheric correction using the DOS1 method (Dark Object Subtraction 1), which is an image-based technique (for more information about conversion to TOA and DOS1 correction, see Image conversion to reflectance).

Once the input is selected, available bands are listed in the metadata table.

## 3.4.3.1.1. ASTER conversion¶

• Select file ASTER L1T : select an ASTER image (file .hdf);
• Apply DOS1 atmospheric correction: if checked, the DOS1 Correction is applied to all the bands;
• Use value as NoData : if checked, pixels having NoData value are not counted during conversion and the DOS1 calculation of DNmin; it is useful when image has a black border (usually pixel value = 0);
• Create Band set and use Band set tools: if checked, bands are added to the active Band set after the conversion; also, the Band set is processed according to the tools checked in the Band set;
• Add bands in a new Band set: if checked, bands are added to a new empty Band set after the conversion;

All the bands found in the Select file ASTER L1T are listed in the table Metadata. For information about Metadata fields visit the ASTER page .

• Date : date of acquisition (e.g. 20130415);
• Sun elevation : Sun elevation in degrees;
• Earth sun distance : Earth Sun distance in astronomical units (automatically calculated if Date is filled;
• UTM zone : UTM zone code of the image;
• UPPERLEFTM : coordinates of the upper left corner of the image;
• LOWERRIGHTM : coordinates of the lower right corner of the image;
• : remove highlighted bands from the table Metadata;
• : table containing the following fields;
• Band: band name;
• UnitConversionCoeff: value for radiance conversion;
• PixelSize: solar irradiance of band;
• BATCH : add this function to the Batch;
• RUN : select an output directory and start the conversion process; only bands listed in the table Metadata are converted; converted bands are saved in the output directory with the prefix RT_ and automatically loaded in QGIS;