description

This repository provides the facilities for ASIP v2 data (webpage). Manual of this dataset is provided here.

DISCLAIMER: This code project is released with automated tests of data engineering aspect of code, not the data science aspect of it. It is meant to guide and help researchers and students get started on sea ice modelling with Convolutional neural networks.

The order of execution of different parts of the code is as follow:

1. Execute the data building
2. Execute the tensorflow training
3. Execute the inference (apply) code
4. Plotting the result of inference

Requirement

just run the following command in your environment in order to install the requirements:

pip install -r requirements.txt

The users of Microsoft VScode can easily open the remote development container with the help of .devcontainer folder and Dockerfile

Usage

This code uses python argparse for reading the input from command line. Each of three scripts including train_model.py, apply_model.py and build_dataset.py can show which argument belongs to them by placing -h after their name. For example, python train_model.py -h shows the ones that belong to training activities.

Execute the data building

By just giving the full absolute address of the folder that contains all of the uncompressed .nc files of ASIP data, data building part of code is able to build the data based on those files and make them ready for further Machine learning training.

This can be done by writing this command for training purposes:

python build_dataset.py /absolute/path/to/the/folder/of/input_files

Only the unmasked locations of data are selected among the others for having a completely clean data in order to feed it for ML training.

HINT: The folder containing input files must have all of the .nc files without any subfoldering

This command will create a folder named output in the folder that contains the build_dataset.py and write all the output files into it.

As an example, for the case of building data from /fold1 folder and store them in /fold2 folder with nersc noise calculation, and having both window size and stride of 400, the command below is used:

python build_dataset.py /fold1 -o /fold2 -n nersc_ -w 400 -s 400

Table below shows how the arguments are working:

---

Argument short form	Argument long form	default value	Description
[]	[]	[no default]	The first and the only positional argument is the path to directory with input netCDF files needed for data building or applying the trained model (inference)
-o	--output_dir	[no default]	Path to directory for output of building (.npz files)
-n	--noise_method	'nersc_'	the method that error calculation had been used for error. Leave as empty string '' for ESA noise corrections or as 'nersc_' for the Nansen center noise correction.
-w	--window_size	700	window size (of sar and ice chart data) for batching calculation (must be dividable to aspect ratio,the ratio between the cell size of primary and secondary input of network)(This will be the size of image samples that has been used for ML training step)
-s	--stride	700	stride (of sar and ice chart data) for batching calculation (must be dividable to aspect ratio,the ratio between the cell size of primary and secondary input of network)(This will be the stride that determines the overlapping areas between image samples for ML training step)
-r	--aspect_ratio	50	The ration between the cell size of primary and secondary input of ML model. stride and window_size must be dividable to it.
-swa	--rm_swath	0	threshold value for comparison with netCDF file.aoi_upperleft_sample to border the calculation
-d	--distance_threshold	0	threshold for distance from land in mask calculation
-a	--step_resolution_sar	1	step for resizing the sar data (default value leads to no resizing)
-b	--step_resolution_output	1	step for resizing the ice chart data (default value leads to no resizing)

---

Execute the tensorflow training

After building the data, you can train the tensorflow model with those .npz files as the result of data building calculation. To do this, run the script train_model.py by setting the address of output folder (which has been used with training mode) from pervious calculation (data building) with '-o' in the arguments.

It is strongly recommend to read the link below before using this part of the code because everything for file based config (including the classes and scripts) is developed based on explanation of this web page: https://stanford.edu/~shervine/blog/keras-how-to-generate-data-on-the-fly

If you want to run the training with scenes that are belong to a specific season of the year(spring,summer,etc), then you can set beginning_day_of_year and ending_day_of_year variable in the arguments of command line in order to make use of the files that are only belong to the period of year between these two numbers. These two numbers are start and end day count from the beginning of the year for reading data between them.

Train the tensorflow can be done by writing this command in order to training from npz files of fold2 folder:

python train_model.py -o /fold2 -bs 4 -p 0.8 -see -sft

In the above example the npz files are being read from /fold2 folder.

Table below shows how the arguments are working:

---

Argument short form	Argument long form	default value	Description
-o	--output_dir	[no default]	Path to directory with output files (.npz files as the output of building data)
-see	--shuffle_on_epoch_end	False (in the case of absence in the arguments)	Flag for Shuffling the training subset of IDs at the end of every epoch during the training
-sft	--shuffle_for_training	False (in the case of absence in the arguments)	Flag for Shuffling the list of IDs before dividing it into two 'training' and 'validation' subsets
-bd	--beginning_day_of_year	0	min threshold value for comparison with scenedate of files for considering a limited subset of files based on their counts from the first of january of the same year
-ed	--ending_day_of_year	365	max threshold value for comparison with scenedate of files for considering a limited subset of files based on their counts from the first of january of the same year
-p	--percentage_of_training	[]	percentage of IDs that should be considered as training data (between 0,1). '1-percentage_of_training' fraction of data is considered as validation data.
-bs	--batch_size	[]	batch size for data generator

---

Execute the inference code

The output of the ML network is the patches of image, not the whole image with original size. For seeing the result of network (as a whole image,i.e. a scene) after training, apply_model.py can be used. To do this, just like previous example of command line of training, we can run the below command in the command line:

python apply_model.py /fold1 -n nersc_ -w 400 -s 400 -bs 4

Hint: If you:

• use resizing for building the data
• use values of stride and window size in a way that there is a overlapping area for building and training.

and then train the network, this apply_model.py code (and consequent plotting) is not applicable. This inference code is only for cases that resizing and overlapping is not used.

This mode is executed in memory based manner. In this case, only the 'nc' files of /fold1 is taking into consideration for applying the trained model on them. The trained model is selected automatically by tensoeflow as the last trained model (configurable by checkpoint file; more information about the saving mechanism and checkpoint file is here).

Hint: it is important to give values of window_size, stride and batch size identical to those of data building calculation. Otherwise, applying the model is meaningless.

A folder named reconstructs_folder will be created at the same level of output_dir and the reconstructed files will be saved inside that folder.

---

Table below shows how the arguments are working:

Argument short form	Argument long form	default value	Description
[]	[]	[no default]	The first and the only positional argument is the path to directory with input netCDF files needed for data building or applying the trained model (inference)
-n	--noise_method	'nersc_'	the method that error calculation had been used for error. Leave as empty string '' for ESA noise corrections or as 'nersc_' for the Nansen center noise correction.
-w	--window_size	700	window size (of sar and ice chart data) for batching calculation (must be dividable to aspect ratio,the ratio between the cell size of primary and secondary input of network)(This will be the size of image samples that has been used for ML training step)
-s	--stride	700	stride (of sar and ice chart data) for batching calculation (must be dividable to aspect ratio,the ratio between the cell size of primary and secondary input of network)(This will be the stride that determines the overlapping areas between image samples for ML training step)
-r	--aspect_ratio	50	The ration between the cell size of primary and secondary input of ML model. stride and window_size must be dividable to it.
-swa	--rm_swath	0	threshold value for comparison with netCDF file.aoi_upperleft_sample to border the calculation
-d	--distance_threshold	0	threshold for distance from land in mask calculation
-a	--step_resolution_sar	1	step for resizing the sar data (default value leads to no resizing)
-b	--step_resolution_output	1	step for resizing the ice chart data (default value leads to no resizing)
-bs	--batch_size	[no default]	batch size for data generator

---

Plotting the result of inference

For plotting, you can run a separate python script called show.py. You have to make sure that the dependencies are ready for this script. It means you have to install scipy and numpy on your env and run the show.py. This show.py code can also be substituted with an interactive jupyter-notebook. Plotting can be done by writing this command:

python show.py