3.3.2. Phenological metrics type B (pheno_B)

Description

  • Purpose: annual land cover mapping. Specifically designed for low capacity PC (minimum requirement: 8GB RAM, at least 50GB free disk volume)
  • Interval: annual (January 1 – December 31).
  • 16-day interval data: four years of data is recommended for metric processing (e.g., to generate 2018 metrics we recommend downloading data from 2015 to 2018).
  • Naming convention: Metrics_pheno_B.xlsx
  • Metric generation code: https://glad.umd.edu/gladtools/Tools/compute_metrics_pheno_B.zip
  • Classification code parameters: Use keyword “pheno_B” to specify this metric set.
  • Require at least 8GB RAM.
  • The metrics dataset size for one tile / one year is 2.3GB.

Methodology

This metric set is design to allow annual land cover and vegetation structure mapping models extrapolation in space and time. It is similar to the pheno_A metric type with a few differences:

  • The number of metrics was significantly reduced to accommodate low capacity PC.
  • The reference ranking by SVVI index was replaced with ranking by NS2 index (normalized ratio of NIR and SWIR2 bands).

The metric methodology is similar to pheno_A type.


Metric types and naming convention

The metrics for each tile is stored in a separate folder as a single-band UInt16 bit GeoTIFF files. The generic naming convention is the following:

YYYY_B_S_C.tif

 

Where:

YYYY – corresponding year

B – spectral band or index

S – statistic

C – corresponding band or index used for ranking (only for metrics extracted from ranking by a corresponding value)

 

 

Example:

2018_blue_max_RN.tif - The metric represents the value of the normalized surface reflectance of the Landsat blue band for the 16-day interval that has the highest red/NIR normalized ration (also known as NDVI) value during the year 2018.

 

The table Metrics_pheno_B.xlsx has details on the bands, indices, and computed statistics.

 

In addition to spectral metrics, the metric generation software produces a set of technical layers including the number of cloud-free 16-day composites, gap-filling algorithm outputs, data quality, and water presence.

 


Software installation

The following software should be installed to generate metrics:


Software application

  • Download all required 16-day composites
  • Download and install software
  • Make a list of tiles to process (single column, tile names only – see example tiles.txt).
  • Use the following command to compute metrics:

> perl C:/GLAD_1.0/metrics_pheno.pl B <tile_list> <year> <input folder> <output folder> <threads>

 

Example:

> perl C:/GLAD_1.0/metrics_pheno.pl B tiles.txt 2018 D:/Data D:/Metrics 1

The command parameters are:

Input folder: the folder with 16-day composite data. It should contain tile data in subfolders.

Output folder: will be created by the code, tile data will be recorded into subfolders.

Threads: the number of parallel processes. The parameter should be increased only if:

  • A computer has multi-core processor (e.g., Intel Xeon)
  • The RAM can hold several processes simultaneously. Each process will use 8GB RAM. To get the total RAM usage, multiply 8GB by the number of processes.