Mapping Invasive Species Using Supervised Machine Learning and AVIRIS-NG

Mapping Invasive Species Using Supervised Machine Learning and AVIRIS-NG#

Overview#

In this notebook, we will use existing data of verified land cover and alien species locations to extract spectra from AVIRIS NG surface reflectance data.

This Notebook borrows heavily from an earlier BioSCape Workshop Notebook, but with updates to reading and analysis of AVIRIS-NG netCDF file formats.

Learning Objectives#

Understand how to inspect and prepare data for machine learning models
Train and interpret a machine learning model
Apply a trained model to AVIRIS imagery to create alien species maps

Load Python Modules#

# Modules imported separately - not available at the time of the workshop managed environment 
# !pip3 install --user xvec
# !pip3 install --user shap
# !pip3 install --user xgboost

from os import path
import datetime as dt 
import geopandas as gpd
import s3fs
import pandas as pd
import xarray as xr
from shapely.geometry import box, mapping, Polygon, MultiPolygon
import rioxarray as riox
import numpy as np
import netCDF4 as nc
import hvplot.xarray
import holoviews as hv
import xvec
import shap
import xgboost
import matplotlib.pyplot as plt
from dask.diagnostics import ProgressBar
import warnings
import earthaccess
#our functions
from utils import get_first_xr

warnings.filterwarnings('ignore')
hvplot.extension('bokeh')

Explore Sample Land Type Plot-Level Data#

For plot-level training data, we will use a small dataset over the Cape Town Peninsula of South Africa of manually collected invasive plant and land cover label

ct_invasive.gpkg

# let's first create a DataFrame and assign labels to each class

label_df = pd.DataFrame({'LandType': ['Bare ground/Rock','Mature Fynbos', 
              'Recently Burnt Fynbos', 'Wetland', 
              'Forest', 'Pine', 'Eucalyptus' , 'Wattle', 'Water'],
               'class': ['0','1','2','3','4','5','6','7','8']})

label_df

	LandType	class
0	Bare ground/Rock	0
1	Mature Fynbos	1
2	Recently Burnt Fynbos	2
3	Wetland	3
4	Forest	4
5	Pine	5
6	Eucalyptus	6
7	Wattle	7
8	Water	8

# Now let's open the dataset, project to the South African UTM projection also used by the AVIRIS-NG airborne data, and merge it with the label data frame created above.
class_data = gpd.read_file('~/shared-public/data/ct_invasive.gpkg')
# class_data.crs
class_data_utm = (class_data
                 .to_crs("EPSG:32734")
                 .merge(label_df, on='class', how='left')
                 )
class_data_utm

	class	group	geometry	LandType
0	0	2	POINT (264211.767 6198008.161)	Bare ground/Rock
1	0	1	POINT (257698.443 6240453.544)	Bare ground/Rock
2	0	1	POINT (260264.755 6239108.581)	Bare ground/Rock
3	0	1	POINT (258793.622 6239111.697)	Bare ground/Rock
4	0	1	POINT (261938.819 6238865.583)	Bare ground/Rock
...	...	...	...	...
314	7	2	POINT (262122.203 6228661.57)	Wattle
315	3	1	POINT (262105.078 6228827.113)	Wetland
316	3	1	POINT (262316.257 6228870.308)	Wetland
317	7	1	POINT (262822.284 6241735.006)	Wattle
318	7	1	POINT (262935.024 6241659.615)	Wattle

319 rows × 4 columns

Summarize and Visualize the Land Types#

# examine the number of plots of each land type
class_data_utm.groupby(['LandType']).size()

LandType
Bare ground/Rock         32
Eucalyptus               30
Forest                   34
Mature Fynbos            44
Pine                     36
Recently Burnt Fynbos    32
Water                    32
Wattle                   24
Wetland                  55
dtype: int64

# The group class will be used to determine training and test data
class_data_utm.groupby(['group']).size()

group
1    254
2     65
dtype: int64

# Let's visualize the plot data in an interactive map, with color by class, using a Google satellite basemap
class_data_utm[['LandType', 'geometry']].explore('LandType', tiles='https://mt1.google.com/vt/lyrs=s&x={x}&y={y}&z={z}', attr='Google')

Make this Notebook Trusted to load map: File -> Trust Notebook

Earthdata Authentication#

# ask for EDL credentials and persist them in a .netrc file
auth = earthaccess.login(strategy="interactive", persist=True)

AVIRIS-NG Data over Cape Town Peninsula#

# search granules
granules = earthaccess.search_data(
    doi='10.3334/ORNLDAAC/2427', # BioSCape: AVIRIS-NG L3
    granule_name = "AVIRIS-NG*", # exclude geojson tile
)

# print one granule
granules[100]

Data: AVIRIS-NG_BIOSCAPE_V02_L3_28_14_QL.tif AVIRIS-NG_BIOSCAPE_V02_L3_28_14_UNC.nc AVIRIS-NG_BIOSCAPE_V02_L3_28_14_RFL.nc

Size: 6760.12 MB

Cloud Hosted: True

vars(granules[100])

{'cloud_hosted': True,
 'uuid': '488868c9-6027-4103-b433-e839d606464c',
 'render_dict': Collection: {'ShortName': 'BioSCape_ANG_V02_L3_RFL_Mosaic_2427', 'Version': '2'}
 Spatial coverage: {'HorizontalSpatialDomain': {'Geometry': {'GPolygons': [{'Boundary': {'Points': [{'Longitude': 18.8167, 'Latitude': -33.438}, {'Longitude': 18.8225, 'Latitude': -33.3487}, {'Longitude': 18.7143, 'Latitude': -33.3439}, {'Longitude': 18.7085, 'Latitude': -33.4332}, {'Longitude': 18.8167, 'Latitude': -33.438}]}}]}}}
 Temporal coverage: {'RangeDateTime': {'BeginningDateTime': '2023-10-22T00:00:00Z', 'EndingDateTime': '2023-11-26T23:59:59Z'}}
 Size(MB): 6760.123710632324
 Data: ['https://data.ornldaac.earthdata.nasa.gov/protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_28_14_QL.tif', 'https://data.ornldaac.earthdata.nasa.gov/protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_28_14_UNC.nc', 'https://data.ornldaac.earthdata.nasa.gov/protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_28_14_RFL.nc']}

def convert_umm_geometry(gpoly):
    """converts UMM geometry to multipolygons"""
    ltln = gpoly[0]["Boundary"]["Points"]
    return Polygon([(p["Longitude"], p["Latitude"]) for p in ltln])

def convert_list_gdf(datag):
    """converts List[] to geopandas dataframe"""
    # create pandas dataframe from json
    df = pd.json_normalize([vars(granule)['render_dict'] for granule in datag])
    # keep only last string of the column names
    df.columns=df.columns.str.split('.').str[-1]
    # creates polygon geometry
    df["geometry"] = df["GPolygons"].apply(convert_umm_geometry)
    # return geopandas dataframe
    return gpd.GeoDataFrame(df, geometry="geometry", crs="EPSG:4326")
    
AVNG_Coverage = convert_list_gdf(granules)
AVNG_Coverage[['native-id', 'geometry']].explore(tiles='https://mt1.google.com/vt/lyrs=s&x={x}&y={y}&z={z}', attr='Google')

Make this Notebook Trusted to load map: File -> Trust Notebook

Open a single AVIRIS-NG Reflectance file to inspect the data#

xarray is an open source project and Python package that introduces labels in the form of dimensions, coordinates, and attributes on top of raw NumPy-like arrays

# search granules that spatially intersects with class_data
single_granule = earthaccess.search_data(
    doi='10.3334/ORNLDAAC/2427', # BioSCape: AVIRIS-NG L3
    granule_name = "AVIRIS-NG_BIOSCAPE_V02_L3_36_11*", # select only one file
)
single_granule[0].data_links(access="direct")

['s3://ornl-cumulus-prod-protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_36_11_QL.tif',
 's3://ornl-cumulus-prod-protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_36_11_UNC.nc',
 's3://ornl-cumulus-prod-protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_36_11_RFL.nc']

# earthaccess open
fh = earthaccess.open(single_granule)
fh

[<File-like object S3FileSystem, ornl-cumulus-prod-protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_36_11_QL.tif>,
 <File-like object S3FileSystem, ornl-cumulus-prod-protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_36_11_UNC.nc>,
 <File-like object S3FileSystem, ornl-cumulus-prod-protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_36_11_RFL.nc>]

def separate_granule_type(fo):
    """separating granules by type"""
    return ([f for f in fo if f.path.endswith("_RFL.nc")],
            [f for f in fo if f.path.endswith("_QL.tif")],
            [f for f in fo if f.path.endswith("_UNC.nc")])
rfl_f, ql_f, unc_f = separate_granule_type(fh)

# plot a single file netcdf
rfl_netcdf = xr.open_datatree(rfl_f[0],
                              engine='h5netcdf', chunks={})
rfl_netcdf = rfl_netcdf.reflectance.to_dataset()
rfl_netcdf = rfl_netcdf.reflectance.where(rfl_netcdf.reflectance>0)
rfl_netcdf

<xarray.DataArray 'reflectance' (wavelength: 425, northing: 2000, easting: 2000)> Size: 7GB
dask.array<where, shape=(425, 2000, 2000), dtype=float32, chunksize=(10, 256, 256), chunktype=numpy.ndarray>
Coordinates:
  * easting     (easting) float64 16kB 7.9e+05 7.9e+05 7.9e+05 ... 8e+05 8e+05
  * northing    (northing) float64 16kB 8.3e+05 8.3e+05 ... 8.2e+05 8.2e+05
  * wavelength  (wavelength) float32 2kB 377.2 382.2 ... 2.496e+03 2.501e+03
Attributes:
    _QuantizeBitGroomNumberOfSignificantDigits:  5
    long_name:                                   Mosaiced Hemispherical Direc...
    grid_mapping:                                transverse_mercator
    orthorectified:                              True

Plot just a red reflectance#

h = rfl_netcdf.sel({'wavelength': 660},method='nearest').hvplot('easting', 'northing',
                                                      rasterize=True, data_aspect=1,
                                                      cmap='magma',frame_width=400,clim=(0,0.3))
h

Plot a quicklook image#

# plot a single file geotif
ql_tif = xr.open_dataset(ql_f[0], engine='rasterio')
h = ql_tif.hvplot.rgb('x', 'y', bands='band', rasterize=True, data_aspect=1, frame_width=400)
h

Select the AVIRIS-NG Flight Line data to selected parameters#

For our analysis demonstration in this Notebook, we’ll narrow the flight lines to the area of the Cape Penisula.

# search granules that spatially intersects with class_data
granules_cp = earthaccess.search_data(
    doi='10.3334/ORNLDAAC/2427', # BioSCape: AVIRIS-NG L3
    bounding_box = tuple(class_data.total_bounds),
    granule_name = "AVIRIS-NG*", # exclude geojson tile
)

AVNG_Coverage = convert_list_gdf(granules_cp)
AVNG_Coverage[['native-id', 'geometry']].explore('native-id', tiles='https://mt1.google.com/vt/lyrs=s&x={x}&y={y}&z={z}', attr='Google')

Make this Notebook Trusted to load map: File -> Trust Notebook

Extract Spectra for each Land Plot#

Now that we are familiar with the data, we want to get the AVIRIS spectra at each label location. Below is a function that does this and returns the result as a xarray

f_cp = earthaccess.open(granules_cp)
rfl_f, ql_f, unc_f = separate_granule_type(f_cp)
AVNG_CP = AVNG_Coverage.to_crs("EPSG:32734")
ds_all =[]
for rfl in rfl_f:
    native_id = path.basename(rfl.path)[:-7]
    geof = AVNG_CP[AVNG_CP["native-id"]==native_id].geometry
    points = class_data_utm.clip(geof)
    n_points = points.shape[0]
    if n_points:
        print(f'got {n_points} point from {native_id}')
        ds = xr.open_datatree(rfl, engine='h5netcdf', chunks={})
        points = points.to_crs(ds.transverse_mercator.crs_wkt)
        ds_all.append(ds.reflectance.to_dataset().xvec.extract_points(points['geometry'], 
                                                                x_coords="easting", 
                                                                y_coords="northing",
                                                                index=True))
ds_all = xr.concat(ds_all, dim='file')

got 40 point from AVIRIS-NG_BIOSCAPE_V02_L3_37_11
got 3 point from AVIRIS-NG_BIOSCAPE_V02_L3_37_12
got 26 point from AVIRIS-NG_BIOSCAPE_V02_L3_38_11
got 3 point from AVIRIS-NG_BIOSCAPE_V02_L3_35_10
got 11 point from AVIRIS-NG_BIOSCAPE_V02_L3_36_12
got 7 point from AVIRIS-NG_BIOSCAPE_V02_L3_39_12
got 22 point from AVIRIS-NG_BIOSCAPE_V02_L3_38_12
got 67 point from AVIRIS-NG_BIOSCAPE_V02_L3_36_11
got 32 point from AVIRIS-NG_BIOSCAPE_V02_L3_34_11
got 4 point from AVIRIS-NG_BIOSCAPE_V02_L3_39_11
got 104 point from AVIRIS-NG_BIOSCAPE_V02_L3_35_11

ds_all

<xarray.Dataset> Size: 6MB
Dimensions:      (file: 11, wavelength: 425, geometry: 319)
Coordinates:
  * wavelength   (wavelength) float32 2kB 377.2 382.2 ... 2.496e+03 2.501e+03
  * geometry     (geometry) object 3kB POINT (797172.168653522 811982.4351414...
    index        (file, geometry) float64 28kB 134.0 133.0 132.0 ... 2.0 300.0
Dimensions without coordinates: file
Data variables:
    fwhm         (file, wavelength) float32 19kB dask.array<chunksize=(1, 425), meta=np.ndarray>
    reflectance  (file, wavelength, geometry) float32 6MB dask.array<chunksize=(1, 10, 3), meta=np.ndarray>
Indexes:
    geometry  GeometryIndex (crs=PROJCS["unnamed",GEOGCS["Ellipse Based",DATUM["Ellipse Based",SPHE ...)

ds = get_first_xr(ds_all)
ds

<xarray.Dataset> Size: 549kB
Dimensions:      (wavelength: 425, index: 319)
Coordinates:
  * wavelength   (wavelength) float32 2kB 377.2 382.2 ... 2.496e+03 2.501e+03
    geometry     (index) object 3kB POINT (797172.168653522 811982.435141402)...
  * index        (index) int64 3kB 134 133 132 247 110 109 ... 77 16 305 2 300
Data variables:
    reflectance  (index, wavelength) float32 542kB dask.array<chunksize=(3, 10), meta=np.ndarray>

This data set just has the spectra. We need to merge with point data to add labels

class_xr =class_data_utm[['class','group']].to_xarray()
ds = ds.merge(class_xr.astype(int),join='left')
ds

<xarray.Dataset> Size: 554kB
Dimensions:      (wavelength: 425, index: 319)
Coordinates:
  * wavelength   (wavelength) float32 2kB 377.2 382.2 ... 2.496e+03 2.501e+03
  * index        (index) int64 3kB 134 133 132 247 110 109 ... 77 16 305 2 300
    geometry     (index) object 3kB POINT (797172.168653522 811982.435141402)...
Data variables:
    reflectance  (index, wavelength) float32 542kB dask.array<chunksize=(3, 10), meta=np.ndarray>
    class        (index) int64 3kB 6 5 5 8 3 3 1 2 3 3 2 ... 1 1 0 8 0 3 0 0 0 4
    group        (index) int64 3kB 1 2 1 1 1 1 2 1 1 2 1 ... 1 1 1 1 1 2 1 1 1 1

We have defined all the operations we want, but becasue of xarrays lazy computation, the calculations have not yet been done. We will now force it to perform this calculations. We want to keep the result in chunks, so we use .persist() and not .compute(). This should take approx 2 - 3 mins

##  DUE TO RUN TIME LENGTH, WE WILL NOT RUN THIS IN THE WORKSHOP - For this workshop, we HAVE SAVED THIS OUTPUT (dsp.nc) and it is available FOR NEXT STEP
# with ProgressBar():
#     dsp = ds.persist()

Inspect AVIRIS spectra#

# recall the class types
label_df

	LandType	class
0	Bare ground/Rock	0
1	Mature Fynbos	1
2	Recently Burnt Fynbos	2
3	Wetland	3
4	Forest	4
5	Pine	5
6	Eucalyptus	6
7	Wattle	7
8	Water	8

dsp_plot = dsp.where(dsp['class']==5, drop=True)
h = dsp_plot['reflectance'].hvplot.line(x='wavelength',by='index',
                                    color='green', alpha=0.5,legend=False)
h

At this point in a real machine learning workflow, you should closely inspect the spectra you have for each class. Do they make sense? Are there some spectra that look weird? You should re-evaluate your data to make sure that the assigned labels are true. This is a very important step

Train and evaluate the ML model#

We will be using a model called xgboost. There are many, many different kinds of ML models. xgboost is a class of models called gradient boosted trees, related to random forests. When used for classification, random forests work by creating multiple decision trees, each trained on a random subset of the data and features, and then averaging their predictions to improve accuracy and reduce overfitting. Gradient boosted trees differ in that they build trees sequentially, with each new tree focusing on correcting the errors of the previous ones. This sequential approach allows xgboost to create highly accurate models by iteratively refining predictions and addressing the weaknesses of earlier trees.

Import the Machine Learning libraries we will use.

import xgboost as xgb
from sklearn.model_selection import GridSearchCV
from sklearn.metrics import accuracy_score, f1_score, precision_score, recall_score, confusion_matrix, ConfusionMatrixDisplay

Our dataset has a label indicating which set (training or test), our data belong to. We wil use this to split it

# recall groups
class_data_utm.groupby(['group']).size()

group
1    254
2     65
dtype: int64

class_data_utm.crs

<Projected CRS: EPSG:32734>
Name: WGS 84 / UTM zone 34S
Axis Info [cartesian]:
- E[east]: Easting (metre)
- N[north]: Northing (metre)
Area of Use:
- name: Between 18°E and 24°E, southern hemisphere between 80°S and equator, onshore and offshore. Angola. Botswana. Democratic Republic of the Congo (Zaire). Namibia. South Africa. Zambia.
- bounds: (18.0, -80.0, 24.0, 0.0)
Coordinate Operation:
- name: UTM zone 34S
- method: Transverse Mercator
Datum: World Geodetic System 1984 ensemble
- Ellipsoid: WGS 84
- Prime Meridian: Greenwich

dtrain = dsp.where(dsp['group']==1,drop=True)
dtest = dsp.where(dsp['group']==2,drop=True)

#create separte datasets for labels and features
y_train = dtrain['class'].values.astype(int)
y_test = dtest['class'].values.astype(int)
X_train = dtrain['reflectance'].values
X_test = dtest['reflectance'].values

Train ML model#

The steps we will go through to train the model are:

First, we define the hyperparameter grid. Initially, we set up a comprehensive grid (param_grid) with multiple values for several hyperparameters of the XGBoost model.
Next, we create an XGBoost classifier object using the XGBClassifier class from the XGBoost library.

We then set up the GridSearchCV object using our defined XGBoost model and the hyperparameter grid. GridSearchCV allows us to perform an exhaustive search over the specified hyperparameter values to find the optimal combination that results in the best model performance. We choose a 5-fold cross-validation strategy (cv=5), meaning we split our training data into five subsets to validate the model’s performance across different data splits. We use accuracy as our scoring metric to evaluate the models.

After setting up the grid search, we fit the GridSearchCV object to our training data (X_train and y_train). This process involves training multiple models with different hyperparameter combinations and evaluating their performance using cross-validation. Our goal is to identify the set of hyperparameters that yields the highest accuracy.

Once the grid search completes, we print out the best set of hyperparameters and the corresponding best score. The grid_search.best_params_ attribute provides the combination of hyperparameters that achieved the highest cross-validation accuracy, while the grid_search.best_score_ attribute shows the corresponding accuracy score. Finally, we extract the best model (best_model) from the grid search results. This model is trained with the optimal hyperparameters and is ready for making predictions or further analysis in our classification task.

This will take approx 30 seconds

# Define the hyperparameter grid
param_grid = {
    'max_depth': [5],
    'learning_rate': [0.1],
    'subsample': [0.75],
    'n_estimators' : [50,100]
}

# Create the XGBoost model object
xgb_model = xgb.XGBClassifier(tree_method='hist')

# Create the GridSearchCV object
grid_search = GridSearchCV(xgb_model, param_grid, cv=5, scoring='accuracy')

# Fit the GridSearchCV object to the training data
grid_search.fit(X_train, y_train)

# Print the best set of hyperparameters and the corresponding score
print("Best set of hyperparameters: ", grid_search.best_params_)
print("Best score: ", grid_search.best_score_)
best_model = grid_search.best_estimator_

Best set of hyperparameters:  {'learning_rate': 0.1, 'max_depth': 5, 'n_estimators': 100, 'subsample': 0.75}
Best score:  0.6376470588235295

Evaluate model performance#

We will use our best model to predict the classes of the test data Then, we calculate the F1 score using f1_score, which balances precision and recall, and print it to evaluate overall performance.

Next, we assess how well the model performs for predicting Pine trees by calculating its precision and recall. Precision measures the accuracy of the positive predictions. It answers the question, “Of all the instances we labeled as Pines, how many were actually Pines?”. Recall measures the model’s ability to identify all actual positive instances. It answers the question, “Of all the actual Pines, how many did we correctly identify?”. You may also be familiar with the terms Users’ and Producers’ Accuracy. Precision = User’ Accuracy, and Recall = Producers’ Accuracy.

Finally, we create and display a confusion matrix to visualize the model’s prediction accuracy across all classes

y_pred = best_model.predict(X_test)

# Step 2: Calculate acc and F1 score for the entire dataset
acc = accuracy_score(y_test, y_pred)
print(f"Accuracy: {acc}")

f1 = f1_score(y_test, y_pred, average='weighted')  # 'weighted' accounts for class imbalance
print(f"F1 Score (weighted): {f1}")

# Step 3: Calculate precision and recall for class 5 (Pine)
precision_class_5 = precision_score(y_test, y_pred, labels=[5], average='macro', zero_division=0)
recall_class_5 = recall_score(y_test, y_pred, labels=[5], average='macro', zero_division=0)

print(f"Precision for Class 5: {precision_class_5}")
print(f"Recall for Class 5: {recall_class_5}")

# Step 4: Plot the confusion matrix
conf_matrix = confusion_matrix(y_test, y_pred)

ConfusionMatrixDisplay(confusion_matrix=conf_matrix).plot()
plt.show()

Accuracy: 0.6615384615384615
F1 Score (weighted): 0.6568699274581629
Precision for Class 5: 0.5
Recall for Class 5: 0.6666666666666666

../_images/1d59e94fafb94f0b3fd77d300ddf04acbdc9fd3735af925f0c3799f0fdff01d6.png

Skipping Some steps in the BioSCape Workshop Tutorial#

For the length of this workshop, we cannot cover all steps that were in the BioSCape Cape Town Workshop. But links are provided here:

8.2.1.8. Interpret and understand ML model

https://ornldaac.github.io/bioscape_workshop_sa/tutorials/Machine_Learning/Invasive_AVIRIS.html#interpret-and-understand-ml-model

Predict over an example AVIRIS scene#

We now have a trained model and are ready to deploy it to generate predictions across an entire AVIRIS scene and map the distribution of invasive plants. This involves handling a large volume of data, so we need to write the code to do this intelligently. We will accomplish this by applying the .predict() method of our trained model in parallel across the chunks of the AVIRIS xarray. The model will receive one chunk at a time so that the data is not too large, but it will be able to perform this operation in parallel across multiple chunks, and therefore will not take too long.

This model was only trained on data covering natural vegetaton in the Cape Peninsula, It is important that we only predict in the areas that match our training data. We will therefore filter to scenes that cover the Cape Peninsula and mask out non-protected areas

SAPAD_2024.gpkg

#south africa protected areas
SAPAD = (gpd.read_file('~/shared-public/data/SAPAD_2024.gpkg')
         .query("SITE_TYPE!='Marine Protected Area'")
        )
#SAPAD.plot()
#SAPAD.to_crs("EPSG:32734")
SAPAD.crs

<Geographic 2D CRS: EPSG:4326>
Name: WGS 84
Axis Info [ellipsoidal]:
- Lat[north]: Geodetic latitude (degree)
- Lon[east]: Geodetic longitude (degree)
Area of Use:
- name: World.
- bounds: (-180.0, -90.0, 180.0, 90.0)
Datum: World Geodetic System 1984 ensemble
- Ellipsoid: WGS 84
- Prime Meridian: Greenwich

# Get the bounding box of the training data
bbox = class_data_utm.total_bounds  # (minx, miny, maxx, maxy)
#bbox
gdf_bbox = gpd.GeoDataFrame({'geometry': [box(*bbox)]}, crs=class_data_utm.crs)  # Specify the CRS
gdf_bbox['geometry'] = gdf_bbox.buffer(500)
gdf_bbox.crs

<Projected CRS: EPSG:32734>
Name: WGS 84 / UTM zone 34S
Axis Info [cartesian]:
- E[east]: Easting (metre)
- N[north]: Northing (metre)
Area of Use:
- name: Between 18°E and 24°E, southern hemisphere between 80°S and equator, onshore and offshore. Angola. Botswana. Democratic Republic of the Congo (Zaire). Namibia. South Africa. Zambia.
- bounds: (18.0, -80.0, 24.0, 0.0)
Coordinate Operation:
- name: UTM zone 34S
- method: Transverse Mercator
Datum: World Geodetic System 1984 ensemble
- Ellipsoid: WGS 84
- Prime Meridian: Greenwich

#south africa protected areas
SAPAD = (gpd.read_file('~/shared-public/data/SAPAD_2024.gpkg')
         .query("SITE_TYPE!='Marine Protected Area'")
        )
SAPAD = SAPAD.to_crs("EPSG:32734")

# Get the bounding box of the training data
bbox = class_data_utm.total_bounds  # (minx, miny, maxx, maxy)
gdf_bbox = gpd.GeoDataFrame({'geometry': [box(*bbox)]}, crs=class_data_utm.crs)  # Specify the CRS
gdf_bbox['geometry'] = gdf_bbox.buffer(500)

# protected areas that intersect with the training data
SAPAD_CT = SAPAD.overlay(gdf_bbox,how='intersection')

#keep only AVIRIS scenes that intersects with CT protected areas
AVNG_sapad = AVNG_CP[AVNG_CP.intersects(SAPAD_CT.unary_union)]

m = AVNG_sapad[['native-id','geometry']].explore('native-id')
m

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SAPAD.keys()

Index(['WDPAID', 'CUR_NME', 'WMCM_TYPE', 'MAJ_TYPE', 'SITE_TYPE', 'D_DCLAR',
       'LEGAL_STAT', 'GIS_AREA', 'PROC_DOC', 'Shape_Leng', 'Shape_Area',
       'geometry'],
      dtype='object')

#map = AVNG_Coverage[['fid', 'geometry']].explore('fid')
map = SAPAD[['SITE_TYPE', 'geometry']].explore('SITE_TYPE')
map

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Here is the function that we will actually apply to each chunk. Simple really. The hard work is getting the data into and out of this functiON

def predict_on_chunk(chunk, model):
    probabilities = model.predict_proba(chunk)
    return probabilities

Now we define the funciton that takes as input the path to the AVIRIS file and pass the data to the predict function. THhs is composed of 4 parts:

Part 1: Opens the AVIRIS data file using xarray and sets a condition to identify valid data points where reflectance values are greater than zero.
Part 2: Applies all the transformations that need to be done before the data goes to the model. It the spatial dimensions (x and y) into a single dimension, filters wavelengths, and normalizes the reflectance data.
Part 3: Applies the machine learning model to the normalized data in parallel, predicting class probabilities for each data point using xarray’s apply_ufunc method. Most of the function invloves defining what to do with the dimensions of the old dataset and the new output
Part 4: Unstacks the data to restore its original dimensions, sets spatial dimensions and coordinate reference system (CRS), clips the data, and transposes the data to match expected formats before returning the results.

def predict_xr(file,geometries):

    rfl_f, ql_f, unc_f = separate_granule_type(file)
    native_id = path.basename(rfl_f[0].path)[:-7]
    
    #part 1 - opening file
    #open the file
    print(f'file: {rfl_f[0]}')
    ds = xr.open_datatree(rfl_f[0], engine='h5netcdf', chunks='auto')
    
    #get the geometries of the protected areas for masking
    ds_crs = ds.transverse_mercator.crs_wkt
    geometries = geometries[geometries["native-id"]==native_id].to_crs(ds_crs).geometry.apply(mapping)
    # geometries = geometries.to_crs(ds_crs).geometry.apply(mapping)
    
    #condition to use for masking no data later
    condition = (ds['reflectance'] > -1).any(dim='wavelength')
    
    #stack the data into a single dimension. This will be important for applying the model later
    ds = ds.reflectance.to_dataset().stack(sample=('easting','northing'))
    
    #part 2 - pre-processing
    #remove bad wavelenghts
    wavelengths_to_drop = ds.wavelength.where(
        (ds.wavelength < 450) |
        (ds.wavelength >= 1340) & (ds.wavelength <= 1480) |
        (ds.wavelength >= 1800) & (ds.wavelength <= 1980) |
        (ds.wavelength > 2400), drop=True
    )
    # Use drop_sel() to remove those specific wavelength ranges
    ds = ds.drop_sel(wavelength=wavelengths_to_drop)
    
    #normalise the data
    l2_norm = np.sqrt((ds['reflectance'] ** 2).sum(dim='wavelength'))
    ds['reflectance'] = ds['reflectance'] / l2_norm
    
     
    #part 3 - apply the model over chunks
    result = xr.apply_ufunc(
        predict_on_chunk,
        ds['reflectance'].chunk(dict(wavelength=-1)),
        input_core_dims=[['wavelength']],#input dim with features
        output_core_dims=[['class']],  # name for the new output dim
        exclude_dims=set(('wavelength',)),  #dims to drop in result
        output_sizes={'class': 9}, #length of the new dimension
        output_dtypes=[np.float32],
        dask="parallelized",
        kwargs={'model': best_model}
    )
    
    #part 4 - post-processing
    result = result.where((result >= 0) & (result <= 1), np.nan) #valid values
    result = result.unstack('sample') #remove the stack
    result = result.rio.set_spatial_dims(x_dim='easting',y_dim='northing') #set the spatial dims
    result = result.rio.write_crs(ds_crs) #set the CRS
    result = result.rio.clip(geometries) #clip to the protected areas and no data
    result = result.transpose('class', 'northing', 'easting') #transpose the data rio expects it this way
    
    return result   

Let’s test that it works on a single file before we run it through 100s of GB of data.

test  = predict_xr(earthaccess.open(single_granule),AVNG_sapad)
test

file: <File-like object S3FileSystem, ornl-cumulus-prod-protected/bioscape/BioSCape_ANG_V02_L3_RFL_Mosaic/data/AVIRIS-NG_BIOSCAPE_V02_L3_36_11_RFL.nc>

<xarray.DataArray 'reflectance' (class: 9, northing: 2000, easting: 1999)> Size: 144MB
dask.array<transpose, shape=(9, 2000, 1999), dtype=float32, chunksize=(9, 2000, 256), chunktype=numpy.ndarray>
Coordinates:
  * easting      (easting) float64 16kB 7.9e+05 7.9e+05 7.9e+05 ... 8e+05 8e+05
  * northing     (northing) float64 16kB 8.3e+05 8.3e+05 ... 8.2e+05 8.2e+05
    spatial_ref  int64 8B 0
Dimensions without coordinates: class

# Again, recall the labels and LandType classes
label_df

	LandType	class
0	Bare ground/Rock	0
1	Mature Fynbos	1
2	Recently Burnt Fynbos	2
3	Wetland	3
4	Forest	4
5	Pine	5
6	Eucalyptus	6
7	Wattle	7
8	Water	8

# You can see here that we are mapping results for class 1, mature fynbos
test = test.rio.reproject("EPSG:4326",nodata=np.nan)
h = test.isel({'class':1}).hvplot(tiles=hv.element.tiles.EsriImagery(), 
                              project=True,rasterize=True,clim=(0,1),
                              cmap='magma',frame_width=400,data_aspect=1,alpha=0.5)
h

ML models typically provide a single prediction of the most likely outcomes. You can also get probability-like scores (values from 0 to 1) from these models, but they are not true probabilities. If the model gives you a score of 0.6, that means it is more likely than a prediction of 0.5, and less likely than 0.7. However, it does not mean that in a large sample your prediction would be right 60 times out of 100. To get calibrated probabilities from our models, we have to apply additional steps. We can also get a set of predictions from models rather than a single prediction, which reflects the model’s true uncertainty using a technique called conformal predictions. Read more about conformal prediction for geospatial machine learning in this amazing paper:

Singh, G., Moncrieff, G., Venter, Z., Cawse-Nicholson, K., Slingsby, J., & Robinson, T. B. (2024). Uncertainty quantification for probabilistic machine learning in earth observation using conformal prediction. Scientific Reports, 14(1), 16166.

Final steps of the full ML classification are time intensive and are not described in this workshop.#

Steps in BioSCape Cape Town Workshop Tutorial

8.2.1.10. Merge and mosaic results

CREDITS:#

Find all of the October 2025 BioSCape Data Workshop Materials/Notebooks

https://ornldaac.github.io/bioscape_workshop_sa/intro.html

This Notebook is an adaption of Glenn Moncrieff’s BioSCape Data Workshop Notebook: Mapping invasive species using supervised machine learning and AVIRIS-NG

This Notebook accesses and uses an updated version of AVIRIS-NG data with improved corrections and that are in netCDF file formats

Glenn’s lesson borrowed from:

Land cover mapping example on Microsoft Planetary Computer

Mapping Invasive Species Using Supervised Machine Learning and AVIRIS-NG

Contents

Mapping Invasive Species Using Supervised Machine Learning and AVIRIS-NG#

Overview#

Learning Objectives#

Load Python Modules#

Explore Sample Land Type Plot-Level Data#

Summarize and Visualize the Land Types#

Earthdata Authentication#

AVIRIS-NG Data over Cape Town Peninsula#

Open a single AVIRIS-NG Reflectance file to inspect the data#

Plot just a red reflectance#

Plot a quicklook image#

Select the AVIRIS-NG Flight Line data to selected parameters#

Extract Spectra for each Land Plot#

Inspect AVIRIS spectra#

Prep data for ML model#

Train and evaluate the ML model#

Train ML model#

Evaluate model performance#

Skipping Some steps in the BioSCape Workshop Tutorial#

Predict over an example AVIRIS scene#

Final steps of the full ML classification are time intensive and are not described in this workshop.#

CREDITS:#