Getting Started with GEDI L2A Data in Python

This tutorial demonstrates how to work with the Elevation and Height Metrics (GEDI02_A.001) data product.

The Global Ecosystem Dynamics Investigation (GEDI) mission aims to characterize ecosystem structure and dynamics to enable radically improved quantification and understanding of the Earth's carbon cycle and biodiversity. The GEDI instrument produces high resolution laser ranging observations of the 3-dimensional structure of the Earth. GEDI is attached to the International Space Station and collects data globally between 51.6$^{o}$ N and 51.6$^{o}$ S latitudes at the highest resolution and densest sampling of any light detection and ranging (lidar) instrument in orbit to date. The Land Processes Distributed Active Archive Center (LP DAAC) distributes the GEDI Level 1 and Level 2 products. The L1B and L2 GEDI products are archived and distributed in the HDF-EOS5 file format.

---

Use Case Example:

This tutorial was developed using an example use case for a project being completed by the National Park Service. The goal of the project is to use GEDI L2A data to observe tree canopy height and profile over Redwood National Park in northern California.

This tutorial will show how to use Python to open GEDI L2A files, visualize the full orbit of GEDI points (shots), subset to a region of interest, visualize GEDI canopy height, and export subsets of GEDI science dataset (SDS) layers as GeoJSON files that can be loaded into GIS and/or Remote Sensing software programs.

---

Data Used in the Example:

• GEDI L2A Elevation and Height Metrics Data Global Footprint Level - GEDI02_A.001
  • The purpose of the L2A dataset is to provide waveform interpretation and extracted products from each GEDI waveform. This includes ground elevation, canopy top height, relative return energy metrics (describing canopy vertical structure, for example), and many other interpreted products from the return waveforms.
  • Science Dataset (SDS) layers:
    • /rh
    • /elev_lowestmode
    • /elev_highestreturn
    • /lat_lowestmode
    • /lon_lowestmode
    • /shot_number
    • /quality_flag
    • /digital_elevation_model
    • /degrade_flag
    • /sensitivity

---

Topics Covered:

1. Get Started
   1.1 Import Packages
   1.2 Set Up the Working Environment and Retrieve Files
2. Import and Interpret Data
   2.1 Open a GEDI HDF5 File and Read File Metadata
   2.2 Read SDS Metadata and Subset by Beam
3. Visualize a GEDI Orbit
   3.1 Subset by Layer and Create a Geodataframe
   3.2 Visualize a Geodataframe
4. Work with GEDI L2A Data
   4.1 Import and Extract Specific Shots
   4.2 Plot Relative Height Metrics
   4.3 Combine RH Metrics and Waveforms
   4.4 Select Data from non-Default Algorithm
5. Plot Transects
   5.1 Quality Filtering
   5.2 Plot Beam Transects 5.3 Subset Beam Transects
   5.4 Plot RH Metrics Transects
6. Spatial Visualization
   6.1 Import, Subset, and Quality Filter all Beams
   6.2 Spatial Subsetting
   6.3 Visualize All Beams: Canopy Height and Elevation
7. Export Subsets as GeoJSON Files

---

Before Starting this Tutorial:

Setup and Dependencies

It is recommended to use Conda, an environment manager to set up a compatible Python environment. Download Conda for your OS here: https://www.anaconda.com/download/. Once you have Conda installed, Follow the instructions below to successfully setup a Python environment on Linux, MacOS, or Windows.

This Python Jupyter Notebook tutorial has been tested using Python version 3.7. Conda was used to create the python environment.

• Using your preferred command line interface (command prompt, terminal, cmder, etc.) type the following to successfully create a compatible python environment:

  conda create -n geditutorial -c conda-forge --yes python=3.7 h5py shapely geopandas pandas geoviews holoviews

  conda activate geditutorial

  jupyter notebook

If you do not have jupyter notebook installed, you may need to run:

conda install jupyter notebook

Having trouble getting a compatible Python environment set up? Contact LP DAAC User Services at: https://lpdaac.usgs.gov/lpdaac-contact-us/

If you prefer to not install Conda, the same setup and dependencies can be achieved by using another package manager such as pip.

---

Example Data:

This tutorial uses the GEDI L2A observation from June 19, 2019 (orbit 02932). Use the link below to download the file directly from the LP DAAC Data Pool:

• https://e4ftl01.cr.usgs.gov/GEDI/GEDI02_A.001/2019.06.19/GEDI02_A_2019170155833_O02932_T02267_02_001_01.h5 (5.93 GB)

A NASA Earthdata Login account is required to download the data used in this tutorial. You can create an account at the link provided.

You will need to have the file above downloaded into the same directory as this Jupyter Notebook in order to successfully run the code below.

Source Code used to Generate this Tutorial:

The repository containing all of the required files is located at: https://git.earthdata.nasa.gov/projects/LPDUR/repos/gedi-tutorials/browse

• Jupyter Notebook
• Redwood National Park GeoJSON
  • Contains the administrative boundary for Redwood National Park, available from: Administrative Boundaries of National Park System Units 12/31/2017 - National Geospatial Data Asset (NGDA) NPS National Parks Dataset
• waveform.csv

NOTE: This tutorial was developed for GEDI L2A files and should only be used for those products.

---

1. Get Started

1.1 Import Packages

Import the required packages and set the input/working directory to run this Jupyter Notebook locally.

import os
import h5py
import numpy as np
import pandas as pd
import geopandas as gp
from shapely.geometry import Point
import geoviews as gv
from geoviews import opts, tile_sources as gvts
import holoviews as hv
gv.extension('bokeh', 'matplotlib')