Latest DIC/Strain Improvements. #241

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Merged

JoelPhys merged 16 commits into dev from DIC-dev

Feb 3, 2026

.github/workflows/tests.yml

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+Diff line change
@@ Expand Up / @@ -13,7 +13,7 @@ jobs: @@
           fail-fast: false
           matrix:
             os: [ubuntu-latest, windows-latest, macos-14, macos-15-intel, macos-latest]
-            env-type: [pip, uv, conda]
+            env-type: [pip]
             include:
               - os: macos-14
                 llvm: llvm@15
@@ Expand All / @@ -30,18 +30,6 @@ jobs: @@
             with:
               python-version: '3.11'
-          - name: Install uv
-            if: matrix.env-type == 'uv'
-            uses: astral-sh/setup-uv@v4
-          - name: Set up Miniconda
-            if: matrix.env-type == 'conda'
-            uses: conda-incubator/setup-miniconda@v3
-            with:
-              auto-update-conda: true
-              python-version: '3.11'
-              activate-environment: test-env
           - name: Set default compiler on macOS to GCC
             if: startsWith(matrix.os, 'macos')
             run: |
@@ Expand All / @@ -61,25 +49,12 @@ jobs: @@
               pip install -e . -v
               pip install pytest pytest-mock
-          - name: Install with uv
-            if: matrix.env-type == 'uv'
-            run: |
-              uv pip install --system -e . -v
-              uv pip install --system pytest pytest-mock
-          - name: Install with conda
-            if: matrix.env-type == 'conda'
-            run: |
-              conda install -y pip
-              pip install -e . -v
-              pip install pytest pytest-mock
           - name: Smoke test
             run: python -c "import pyvale"
           - name: Run sensorsim and DIC tests
             shell: bash -el {0}
-            run: pytest -v tests/dic/. tests/sensorsim/.
+            run: pytest -v tests/dic/. tests/sensorsim/. tests/strain/.
           - name: Run blender tests (skip macOS ARM)
             if: ${{ !startsWith(matrix.os, 'macos') || contains(matrix.os, 'intel') }}
@@ Expand Down @@

src/pyvale/dic/cpp/dicfourier.cpp

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+Diff line change
@@ Expand Up / @@ -23,7 +23,7 @@ @@
     // DIC Header files
     #include "dicfourier.hpp"
     #include "dicsubset.hpp"
-    #include "dicinterpolator.hpp"
+    #include "dicinterp.hpp"
     namespace fourier {
@@ Expand Down @@

src/pyvale/dic/cpp/dicfourier.hpp

-Original file line number
+Diff line change
@@ Expand Up / @@ -19,7 +19,7 @@ @@
     #include <Eigen/Dense>
     // DIC Header files
-    #include "./dicinterpolator.hpp"
+    #include "./dicinterp.hpp"
     #include "./dicsubset.hpp"
     #include "./dicutil.hpp"
@@ Expand Down @@

src/pyvale/dic/cpp/dicinterp.hpp

-Original file line number
+Diff line change
@@ -0,0 +1,97 @@
+    // ================================================================================
+    // pyvale: the python validation engine
+    // License: MIT
+    // Copyright (C) 2025 The Computer Aided Validation Team
+    // ================================================================================
+    #ifndef DICINTERP_H
+    #define DICINTERP_H
+    // STD library Header files
+    // Program Header files
+    inline int idx_from_2d(const int x, const int y, const int length){
+        return y*length+x;
+    }
+    /**
+     * @brief namespace for bicubic spline interpolation.
+     *
+     * Based on the implementation by GNU Scientific Library (GSL).
+     * Main difference is the removal of the binary search for index lookup.
+     * For use in DIC, we only ever need integer locations and therefore its
+     * sufficient to get the floor value of the subpixel location.
+     *
+     */
+    struct InterpVals {
+        double f;
+        double dfdx;
+        double dfdy;
+    };
+    class Interpolator {
+    public:
+        int px_vert;
+        int px_hori;
+        /**
+         * @brief Evaluates the bicubic interpolation at a specified point.
+         *
+         * Computes the interpolated value at (x,y) using bicubic interpolation from the surrounding pixel values.
+         *
+         * @param x The x-coordinate of the interpolation point
+         * @param y The y-coordinate of the interpolation point
+         * @return The interpolated value at (x,y)
+         */
+        virtual double eval(const int ss_x, const int ss_y, const double subpx_x, const double subpx_y) const = 0;
+        /**
+         * @brief Evaluates the x-derivative of bicubic interpolation at a specified point.
+         *
+         * Computes the partial derivative with respect to x at point (x,y).
+         *
+         * @param x The x-coordinate of the point
+         * @param y The y-coordinate of the point
+         * @return The x-derivative of the interpolated function at (x,y)
+         */
+        virtual double eval_dx(const int ss_x, const int ss_y, const double subpx_x, const double subpx_y) const = 0;
+        /**
+         * @brief Evaluates the y-derivative of bicubic interpolation at a specified point.
+         *
+         * Computes the partial derivative with respect to y at point (x,y).
+         *
+         * @param x The x-coordinate of the point
+         * @param y The y-coordinate of the point
+         * @return The y-derivative of the interpolated function at (x,y)
+         */
+        virtual double eval_dy(const int ss_x, const int ss_y, const double subpx_x, const double subpx_y) const = 0;
+        /**
+         * @brief Evaluates the bicubic interpolation and its derivatives at a specified point.
+         *
+         * Computes the interpolated value and its partial derivatives at (x,y) in a single call.
+         *
+         * @param x The x-coordinate of the point
+         * @param y The y-coordinate of the point
+         * @return Data struct containing the interpolated value and its x and y derivatives
+         */
+        virtual InterpVals eval_and_derivs(const int ss_x, const int ss_y, const double subpx_x, const double subpx_y) const = 0;
+        virtual ~Interpolator() = default;
+    };
+    #endif //DICINTERP_H

src/pyvale/dic/cpp/dicinterpBspline.cpp

-Original file line number
+Diff line change
@@ -0,0 +1,201 @@
+    // ================================================================================
+    // pyvale: the python validation engine
+    // License: MIT
+    // Copyright (C) 2025 The Computer Aided Validation Team
+    // ================================================================================
+    #include <vector>
+    #include <cmath>
+    #include <algorithm>
+    #include "./dicinterpBspline.hpp"
+    Bspline::Bspline(double* img, int px_hori, int px_vert){
+        // intitialise vars used globally within Interpolator.
+        this->image = img;
+        this->px_vert = px_vert;
+        this->px_hori = px_hori;
+        coeff.resize(px_vert*px_hori);
+        for (int i = 0; i < px_hori*px_vert; i++){
+            coeff[i] = img[i];
+        }
+        prefilter_x();
+        prefilter_y();
+    }
+    // 1D cubic B-spline basis and derivatives
+    inline void Bspline::basis(double t, double B[4]) {
+        double tt = t*t, ttt = tt*t;
+        B[0] = (1.0 - 3.0*t + 3.0*tt - ttt) / 6.0;
+        B[1] = (4.0 - 6.0*tt + 3.0*ttt) / 6.0;
+        B[2] = (1.0 + 3.0*t + 3.0*tt - 3.0*ttt) / 6.0;
+        B[3] = ttt / 6.0;
+    }
+    inline void Bspline::basis_d(double t, double Bd[4]) {
+        double tt = t*t;
+        Bd[0] = (-3.0 + 6.0*t - 3.0*tt) / 6.0;
+        Bd[1] = (-12.0*t + 9.0*tt) / 6.0;
+        Bd[2] = (3.0 + 6.0*t - 9.0*tt) / 6.0;
+        Bd[3] = (3.0*tt) / 6.0;
+    }
+    void Bspline::prefilter_x() {
+        const double z = std::sqrt(3.0) - 2.0;
+        const double lambda = (1.0 - z)*(1.0 - 1.0/z);
+        // Normalize
+        for (int y = 0; y < px_vert; y++)
+            for (int x = 0; x < px_hori; x++)
+                coeff[y*px_hori + x] *= lambda;
+        // Causal
+        for (int y = 0; y < px_vert; y++) {
+            double* row = &coeff[y*px_hori];
+            for (int x = 1; x < px_hori; x++)
+                row[x] += z * row[x-1];
+        }
+        // Anticausal
+        for (int y = 0; y < px_vert; y++) {
+            double* row = &coeff[y*px_hori];
+            row[px_hori-1] = z/(z*z - 1.0) * row[px_hori-1];
+            for (int x = px_hori-2; x >= 0; x--)
+                row[x] = z*(row[x+1] - row[x]);
+        }
+    }
+    // -------------------------------------------------------
+    // Prefilter along each column
+    // -------------------------------------------------------
+    void Bspline::prefilter_y() {
+        const double z = std::sqrt(3.0) - 2.0;
+        const double lambda = (1.0 - z)*(1.0 - 1.0/z);
+        // Normalize
+        for (int y = 0; y < px_vert; y++)
+            for (int x = 0; x < px_hori; x++)
+                coeff[y*px_hori + x] *= lambda;
+        // Causal
+        for (int x = 0; x < px_hori; x++) {
+            for (int y = 1; y < px_vert; y++)
+                coeff[y*px_hori + x] += z * coeff[(y-1)*px_hori + x];
+        }
+        // Anticausal
+        for (int x = 0; x < px_hori; x++) {
+            coeff[(px_vert-1)*px_hori + x] = z/(z*z - 1.0) * coeff[(px_vert-1)*px_hori + x];
+            for (int y = px_vert-2; y >= 0; y--)
+                coeff[y*px_hori + x] = z*(coeff[(y+1)*px_hori + x] - coeff[y*px_hori + x]);
+        }
+    }
+    double Bspline::eval(const int ss_x, const int ss_y, const double subpx_x, double subpx_y) const {
+        int ix = (int)floor(subpx_x);
+        int iy = (int)floor(subpx_y);
+        double tx = subpx_x - ix;
+        double ty = subpx_y - iy;
+        double Bx[4], By[4];
+        basis(tx, Bx);
+        basis(ty, By);
+        double f = 0.0;
+        for (int j = 0; j < 4; j++) {
+            int yy = std::clamp(iy + j - 1, 0, px_vert-1);
+            for (int i = 0; i < 4; i++) {
+                int xx = std::clamp(ix + i - 1, 0, px_hori-1);
+                double c = coeff[yy*px_hori + xx];
+                f += c * Bx[i] * By[j];
+            }
+        }
+        return f;
+    }
+    double Bspline::eval_dx(const int ss_x, const int ss_y, const double subpx_x, double subpx_y) const {
+        int ix = (int)floor(subpx_x);
+        int iy = (int)floor(subpx_y);
+        double tx = subpx_x - ix;
+        double ty = subpx_y - iy;
+        double By[4], dBx[4];
+        basis(ty, By);
+        basis_d(tx, dBx);
+        double dfdx = 0.0;
+        for (int j = 0; j < 4; j++) {
+            int yy = std::clamp(iy + j - 1, 0, px_vert-1);
+            for (int i = 0; i < 4; i++) {
+                int xx = std::clamp(ix + i - 1, 0, px_hori-1);
+                double c = coeff[yy*px_hori + xx];
+                dfdx += c * dBx[i] * By[j];
+            }
+        }
+        return dfdx;
+    }
+    double Bspline::eval_dy(const int ss_x, const int ss_y, const double subpx_x, double subpx_y) const {
+        int ix = (int)floor(subpx_x);
+        int iy = (int)floor(subpx_y);
+        double tx = subpx_x - ix;
+        double ty = subpx_y - iy;
+        double Bx[4], dBy[4];
+        basis(tx, Bx);
+        basis_d(ty, dBy);
+        double dfdy = 0.0;
+        for (int j = 0; j < 4; j++) {
+            int yy = std::clamp(iy + j - 1, 0, px_vert-1);
+            for (int i = 0; i < 4; i++) {
+                int xx = std::clamp(ix + i - 1, 0, px_hori-1);
+                double c = coeff[yy*px_hori + xx];
+                dfdy += c * Bx[i] * dBy[j];
+            }
+        }
+        return dfdy;
+    }
+    InterpVals Bspline::eval_and_derivs(const int ss_x, const int ss_y, const double subpx_x, double subpx_y) const {
+        int ix = (int)floor(subpx_x);
+        int iy = (int)floor(subpx_y);
+        double tx = subpx_x - ix;
+        double ty = subpx_y - iy;
+        double Bx[4], By[4], dBx[4], dBy[4];
+        basis(tx, Bx);
+        basis(ty, By);
+        basis_d(tx, dBx);
+        basis_d(ty, dBy);
+        InterpVals out {0,0,0};
+        for (int j = 0; j < 4; j++) {
+            int yy = std::clamp(iy + j - 1, 0, px_vert-1);
+            for (int i = 0; i < 4; i++) {
+                int xx = std::clamp(ix + i - 1, 0, px_hori-1);
+                double c = coeff[yy*px_hori + xx];
+                out.f += c * Bx[i] * By[j];
+                out.dfdx += c * dBx[i] * By[j];
+                out.dfdy += c * Bx[i] * dBy[j];
+            }
+        }
+        return out;
+    }

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