pyggms 0.1.0

A Python package for seafloor topography modeling using GGM and EGGM

pyggms

pyggms is a Python package for gravity field modeling and gridded prediction. It provides GGM (Generalized Gravity Model) and EGGM (Extended Generalized Gravity Model) for fitting and interpolating 2D gridded data such as satellite and shipborne gravity measurements.

Features

• Grid modeling based on radial basis functions (RBF)
• Joint fitting of irregular shipborne points and gridded gravity anomalies
• Direct generation of prediction matrices for output grids
• Built-in latitude/longitude bounds and Gaussian smoothing parameters

Installation

Dependencies

• Python >= 3.7
• numpy
• opencv-python

Install via pip

pip install pyggms
git clone https://github.com/WChao1988/pyggm_projects.git
cd pyggms
pip install .

Quick start

import numpy as np from pyggms import ggmModel, eggmModel from cv2 import resize

Load data

faa_matrix = np.loadtxt('faa_matrix_22_19_157_160.txt') faa_matrix = resize(faa_matrix, (720, 720)) # resample to target size ship_grid = np.loadtxt('ship_matrix_22_19_157_160.txt')

Initialize GGM model

gm = ggmModel( c0=1.63, lat_up=22, lat_down=19, lon_left=157, lon_right=160, radius=0.5, sigma=0.0001 )

Fit the model

reference_depth = ship_grid.min() gm.fit(faa_matrix, ship_grid, reference_depth)

Predict full grid

ggm_matrix = gm.prediction_matrix()

Initialize EGGM model

egm = eggmModel( c0=1.63, c1=0.83, lat_up=22, lat_down=19, lon_left=157, lon_right=160, radius=0.5, sigma=0.5 )

Fit EGGM model

egm.fit(ggm_matrix, faa_matrix, ship_grid, reference_depth)

Final prediction

eggm_matrix = egm.predict_matrix()

API Reference

Parameter	Type	Description
c0	float	Primary model coefficient
lat_up, lat_down	float	Northern / southern latitude bounds
lon_left, lon_right	float	Western / eastern longitude bounds
radius	float	Radial basis function radius
sigma	float	Regularization parameter

Main methods:

fit(faa_matrix, ship_grid, reference_depth): Fit the model

prediction_matrix(): Return the fitted regular grid matrix