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Gaussian Processes for Aircraft Detection

These experiments test the performance of a Gaussian process (GP) classifier with various kernels on the UC Merced land use land cover (LULC) dataset. The motivation comes from the paper Gaussian Processes for Object Detection in High Resolution Remote Sensing Images (Liang et al. 2016), where the authors use a combination of a SIFT or SURF feature extractor and a GP with squared exponential / radial basis function (RBF) kernel to classify aerial images as airplane / not airplane.

Run with virtual environment

The settings for the experiment are in config.yaml.

Set up environment

pipenv is used for managing dependencies. Before running any experiments, ensure that wget is installed (using brew install wget with linux), all packages are installed, and MLflow is set up. Then pull the data from the UC Merced site. This can be done using:

# install dependencies and create virtual env
pipenv install 

# setup mlflow
pipenv run sh scripts/setup_mlflow.sh

# get data
sh scripts/get_imagery.sh

from the root directory. This will set up the environment and experiments and will create a data directory with all of the images.

Run experiments

To run multiple experiments with pipenv (also from the root directory):

pipenv run sh run_batch.sh

To run a single experiment with a choice of kernel (ex. Linear kernel):

pipenv run python run.py --kernel=Linear_Kernel

The full list of kernels used is in the KERNELS dictionary in run.py.

Run with Docker

First, ensure that Docker is able to use at least 6 GB of memory. The default 2 GB memory will cause the process to die. Using larger images will require more memory - ex. 150 x 150 images require at least 10 GB of memory and 224 x 224 images require at least 16 GB memory.

Build the container:

docker build -t aircraft-detection .

Run the container with port mapped to 5000 for MLflow:

docker run -it -p 5000:5000 --name aircraft-detection aircraft-detection

To run experiments, use the pipenv runcommands from the previous section.

Viewing the results in MLflow

To view the results of each experiment, first enter the container if needed:

docker start -i aircraft-detection

Then use (from the root directory containing mlruns/):

pipenv run mlflow ui --host 0.0.0.0

The MLflow tracking UI will be available locally at localhost:5000.

Note about Cholesky decomposition error

Numerical instability exists in the DotProduct kernel due to rounding errors. In our case, this could be due to collinearity in the large number of correlated features. To overcome it, we add a WhiteKernel to it with a small noise level. This is equivalent to adding a small number to the diagonal of the covariance matrix, which can also be done using the nugget of the GP.