diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 9a4a31c..a0d2a72 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -3,6 +3,7 @@ find_package(Eigen3 CONFIG REQUIRED)
 add_library(geopro_core STATIC
   geo/LocalFrame.cpp
   model/ColorScale.cpp
+  algo/IdwInterpolator.cpp
 )
 
 target_include_directories(geopro_core PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
diff --git a/src/core/algo/IInterpolator.hpp b/src/core/algo/IInterpolator.hpp
new file mode 100644
index 0000000..cea17c1
--- /dev/null
+++ b/src/core/algo/IInterpolator.hpp
@@ -0,0 +1,21 @@
+#pragma once
+#include <vector>
+#include "model/Field.hpp"
+namespace geopro::core {
+
+struct PointSet { std::vector<double> x, y, z, v; };
+struct GridSpec {
+    int nx, ny, nz;
+    double ox, oy, oz;     // 原点
+    double dx, dy, dz;     // 步长
+    double power;          // IDW 幂
+    double maxDist;        // 超过则 blank(NaN)，约束插值域(设计 §10)
+};
+
+class IInterpolator {
+public:
+    virtual ~IInterpolator() = default;
+    virtual ScalarVolume interpolate(const PointSet& pts, const GridSpec& spec) const = 0;
+};
+
+}  // namespace geopro::core
diff --git a/src/core/algo/IdwInterpolator.cpp b/src/core/algo/IdwInterpolator.cpp
new file mode 100644
index 0000000..c2e59a3
--- /dev/null
+++ b/src/core/algo/IdwInterpolator.cpp
@@ -0,0 +1,31 @@
+#include "algo/IdwInterpolator.hpp"
+#include <cmath>
+#include <limits>
+namespace geopro::core {
+
+ScalarVolume IdwInterpolator::interpolate(const PointSet& pts, const GridSpec& s) const {
+    ScalarVolume vol(s.nx, s.ny, s.nz);
+    const double nan = std::numeric_limits<double>::quiet_NaN();
+    const size_t n = pts.v.size();
+    for (int k = 0; k < s.nz; ++k)
+        for (int j = 0; j < s.ny; ++j)
+            for (int i = 0; i < s.nx; ++i) {
+                const double gx = s.ox + i * s.dx, gy = s.oy + j * s.dy, gz = s.oz + k * s.dz;
+                double wsum = 0.0, vsum = 0.0, nearest = std::numeric_limits<double>::max();
+                bool hit = false; double hitVal = 0.0;
+                for (size_t p = 0; p < n; ++p) {
+                    const double ddx = gx - pts.x[p], ddy = gy - pts.y[p], ddz = gz - pts.z[p];
+                    const double d = std::sqrt(ddx * ddx + ddy * ddy + ddz * ddz);
+                    if (d < nearest) nearest = d;
+                    if (d < 1e-12) { hit = true; hitVal = pts.v[p]; break; }
+                    const double w = 1.0 / std::pow(d, s.power);
+                    wsum += w; vsum += w * pts.v[p];
+                }
+                if (hit) vol.at(i, j, k) = hitVal;
+                else if (nearest > s.maxDist || wsum == 0.0) vol.at(i, j, k) = nan;
+                else vol.at(i, j, k) = vsum / wsum;
+            }
+    return vol;
+}
+
+}  // namespace geopro::core
diff --git a/src/core/algo/IdwInterpolator.hpp b/src/core/algo/IdwInterpolator.hpp
new file mode 100644
index 0000000..fe16723
--- /dev/null
+++ b/src/core/algo/IdwInterpolator.hpp
@@ -0,0 +1,8 @@
+#pragma once
+#include "algo/IInterpolator.hpp"
+namespace geopro::core {
+class IdwInterpolator : public IInterpolator {
+public:
+    ScalarVolume interpolate(const PointSet& pts, const GridSpec& spec) const override;
+};
+}  // namespace geopro::core
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 2533525..4d7024a 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -12,6 +12,7 @@ gtest_discover_tests(geopro_tests)
 target_sources(geopro_tests PRIVATE core/test_local_frame.cpp)
 target_sources(geopro_tests PRIVATE core/test_model.cpp)
 target_sources(geopro_tests PRIVATE core/test_color_scale.cpp)
+target_sources(geopro_tests PRIVATE core/test_idw.cpp)
 target_link_libraries(geopro_tests PRIVATE geopro_core)
 
 add_subdirectory(spike)   # spike S3: banded contour 渲染验证
diff --git a/tests/core/test_idw.cpp b/tests/core/test_idw.cpp
new file mode 100644
index 0000000..4799a30
--- /dev/null
+++ b/tests/core/test_idw.cpp
@@ -0,0 +1,26 @@
+#include <gtest/gtest.h>
+#include <cmath>
+#include "algo/IdwInterpolator.hpp"
+using namespace geopro::core;
+
+TEST(Idw, ReproducesSampleAtNode) {
+    PointSet pts;
+    pts.x = {0.0, 10.0}; pts.y = {0.0, 0.0}; pts.z = {0.0, 0.0}; pts.v = {100.0, 200.0};
+    GridSpec spec{ /*nx*/3, /*ny*/1, /*nz*/1, /*ox*/0, /*oy*/0, /*oz*/0, /*dx*/5, /*dy*/1, /*dz*/1,
+                   /*power*/2.0, /*maxDist*/1e9 };
+    IdwInterpolator idw;
+    ScalarVolume vol = idw.interpolate(pts, spec);
+    EXPECT_NEAR(vol.at(0, 0, 0), 100.0, 1e-6);   // x=0 命中点1
+    EXPECT_NEAR(vol.at(2, 0, 0), 200.0, 1e-6);   // x=10 命中点2
+    EXPECT_GT(vol.at(1, 0, 0), 100.0);
+    EXPECT_LT(vol.at(1, 0, 0), 200.0);
+}
+
+TEST(Idw, BlanksOutsideMaxDist) {
+    PointSet pts; pts.x = {0.0}; pts.y = {0.0}; pts.z = {0.0}; pts.v = {50.0};
+    GridSpec spec{2,1,1, 0,0,0, 100,1,1, 2.0, /*maxDist*/1.0};
+    IdwInterpolator idw;
+    ScalarVolume vol = idw.interpolate(pts, spec);
+    EXPECT_NEAR(vol.at(0,0,0), 50.0, 1e-6);       // 命中
+    EXPECT_TRUE(std::isnan(vol.at(1,0,0)));        // 超距 -> NaN(blank)
+}