3.3.2. Phenological metrics type B (pheno_B)
- 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.
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 – 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)
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.
The following software should be installed to generate metrics:
- ActivePerl (https://www.activestate.com/products/activeperl/)
- GLAD_1.0 core package (https://glad.umd.edu/gladtools/Complete_package/GLAD_1.0_master.zip)
- 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>
> 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.