EVMS — Volumetric Inversion of Geological Radioactivity

EVMS is a scientific Python framework to reconstruct a 3D subsurface source-intensity field from surface gamma measurements. It combines a sparse forward model, geological regularization, and an interactive Streamlit interface for reproducible inversion workflows.

Why EVMS

• Sparse, scalable inversion on voxel grids (scipy.sparse, iterative solvers).
• Physics-informed forward model with attenuation and distance kernel.
• Geological priors through layer-aware smoothing and finite fracture barriers.
• Publication-ready outputs: volumetric field export and textured mesh export.
• Interactive analysis, diagnostics, and trust reporting in Streamlit.

Scientific Model (Concise)

Forward model:

$$ M(\mathbf{x}) = \int_V S(\mathbf{r}),G(\mathbf{x},\mathbf{r}),e^{-\mu|\mathbf{x}-\mathbf{r}|},dV + \varepsilon, \qquad G(\mathbf{x},\mathbf{r}) = \frac{1}{|\mathbf{x}-\mathbf{r}|^2 + \epsilon} $$

Voxel discretization:

$$ \mathbf{M} \approx \mathbf{A}\mathbf{S} + \boldsymbol{\varepsilon} $$

Regularized inversion:

$$ \hat{\mathbf{S}} = \arg\min_{\mathbf{S}};|\mathbf{A}\mathbf{S}-\mathbf{M}|_2^2 + \lambda|\mathbf{L}\mathbf{S}|_2^2 $$

where $\mathbf{L}$ is a graph-difference regularizer weighted by layer consistency and fracture crossing penalties.

Installation

conda env create -f environment.yml
conda activate evms-env
pip install -e .

Run the App

streamlit run streamlit_app.py

The app provides:

• Inversion workspace
• Method page (equations and workflow)
• Credits page

Input Data

• Measurements CSV: x,y,z,value
• Grid: .npy mask or .obj mesh (voxelized in-app)
• Fractures JSON: optional finite rectangular fracture patches
• Calibration CSV: optional x,y,z,cps/s

Validation and Testing

pytest

The test suite covers geometry, forward operator behavior, regularization, inversion, calibration, and diagnostics.

Project Website

Documentation and project updates: maxsc4.github.io

Contact

Maxime SOARES CORREIA — soarescorreia@ipgp.fr

Citation

Copy-paste citation:

SOARES CORREIA, M. (2026). EVMS: Volumetric Inversion of Geological Radioactivity from Surface Gamma Measurements (v0.1.1) [Computer software]. GEOPS — Géosciences Paris-Saclay (UMR 8148, CNRS), Université Paris-Saclay. https://doi.org/10.5281/zenodo.18586941