Projected Local Incidence Angle
Projected Local Incidence Angle (PLIA) is the angle between the surface normal and the looking direction of the satellite or the Local Incidence Angle (LIA) projected into the range plane.
Product overview
Product description
Generally, the RGB composite products will be thresholded using the lower and upper thresholds which were derived by empirical experiments on the histogram of the input bands. This step is used to make sure that most of the output composites will not have any extreme value on one or more bands. The detail information on which threshold values were applied on each polarisation/polarisation combination is represented in the table below.
| Polarisation/Polarisation Ratio | Unit | Lower threshold | Upper threshold |
|---|---|---|---|
| Vertical-Vertical (VV) | dB | -14 | -4 |
| Vertical-Horizontal (VH) | dB | -21 | -12 |
| Cross-ratio (VH/VV) | dB | -7 | -1 |
The unit and thresholds for every polarisation/polarisation ratio.
After thresholding the input images, the value of the three input bands will be linearly scaled to the range 0-254. The value itself will be stored as an integer for the sake of space saving. Readers are referred to the subsection "Product variables" for detail information on output data encoding. The value 255 of that output 8-bit integer will be reserved to store no-data value or the data which have been previously masked before.
Product variables
The product variables are defined for each band and each sub-products. Below is an example of the product variables for the Seasonal RGB Composite product for the growing season.
| Composite name | Code name | Band | Polarisation | Month | Threshold min | Threshold max | Type | Byte size | No -data |
|---|---|---|---|---|---|---|---|---|---|
| Seasonal Growing Season | S-COMP007 | Red | VH | June | -21 dB | -12 dB | uint8 | 1 | 255 |
| Seasonal Growing Season | S-COMP007 | Green | VH | July | -21 dB | -12 dB | uint8 | 1 | 255 |
| Seasonal Growing Season | S-COMP007 | Blue | VH | August | -21 dB | -12 dB | uint8 | 1 | 255 |
An example of product variables of the Seasonal RGB Composite product for the growing season
Area and time period
RGB composite product has been computing over the area of Austria from 01st January 2016 to the present.
Temporal resolution
RGB composite images are computed based on the monthly mean backscatter images. This means that there will be a new RGB composite image (for a specific composite) after a month since there are new monthly mean backscatter images every month.
Image timestamps
Different to the soil moisture product, there are the start date and end date of the first and the last acquisition that was used to calculate the monthly mean products, res instead of the date and the time of the acquisition. They can also be found in the metadata header of the original GeoTiff file.
Spatial resolution and sampling
Originally, the S-COMP images are tiled and georeferenced using the TU Wien Equi7(see Data specifications and formats) and have easting and northing coordinates with the pixel spacing of 10m.
Data format
The S-COMP data is originally stored and delivered in GeoTIFF format. GeoTIFF is a standard which allows storing georeferencing information within a TIFF raster image.
Sentinel-1 Projected Local Incidence Angle product at 10m spatial sampling. The scene covers the area of western Innsbruck, Austria.
| Product Name | Projected Local Incidence Angle |
|---|---|
| Code Name | PLIA |
| Category | Sentinel-1 products |
| Spatial Sampling | 10m |
| Temporal Resolution | 3-4 days |
| Unit | Degree |