[v0.1.19] 2026-04-16

- Updated helios-core to v1.3.71

## Plant Architecture
- Added `writePlantStructureUSD()` to export a plant as a USD articulated rigid body for NVIDIA IsaacSim physics (capsule links, spherical joints with E*I/L spring/damper drives, organ mass bodies)
- Added growth animation export via `registerGrowthFrame()`, `writePlantGrowthUSD()`, `clearGrowthFrames()`, and `getGrowthFrameCount()` for time-sampled USD animations importable into Blender

## Context
- Added `updateTimeseriesData()` method to replace the value of an existing timeseries data point at a specified (date, time)
- Added compound-object geometry queries: `getObjectType()`, `getObjectCenter()`, `getObjectBoundingBox()`, `getObjectPrimitiveUUIDs()` (single/list/nested), plus per-type getters for tile, sphere, box, disk, tube, and cone objects (center, size, subdivision count, normal, vertices, radius, node/radius data, axis, length, volume)
- Added primitive geometry queries: `getPatchCenter()`, `getPatchSize()`, `getTriangleVertex()`, `getVoxelCenter()`, `getVoxelSize()`, `getPatchCount()`, `getTriangleCount()`, `getPrimitiveBoundingBox()` (single UUID or list)
- Added `setPrimitiveColor()` for mutating the color of one primitive or a list of primitives, accepting either `RGBcolor` or `RGBAcolor`
- Added `clearPrimitiveData()` and `listPrimitiveData()` for removing and inspecting per-primitive data fields
- Added domain cropping: `cropDomainX()`, `cropDomainY()`, `cropDomainZ()`, and `cropDomain()` to restrict all primitives (or a supplied UUID list) to given XYZ bounds

Author: bnbailey-psl

docs/CHANGELOG.md

@@ -1,5 +1,21 @@
 # Changelog
 
+# [v0.1.19] 2026-04-16
+
+- Updated helios-core to v1.3.71
+
+## Plant Architecture
+- Added `writePlantStructureUSD()` to export a plant as a USD articulated rigid body for NVIDIA IsaacSim physics (capsule links, spherical joints with E*I/L spring/damper drives, organ mass bodies)
+- Added growth animation export via `registerGrowthFrame()`, `writePlantGrowthUSD()`, `clearGrowthFrames()`, and `getGrowthFrameCount()` for time-sampled USD animations importable into Blender
+
+## Context
+- Added `updateTimeseriesData()` method to replace the value of an existing timeseries data point at a specified (date, time)
+- Added compound-object geometry queries: `getObjectType()`, `getObjectCenter()`, `getObjectBoundingBox()`, `getObjectPrimitiveUUIDs()` (single/list/nested), plus per-type getters for tile, sphere, box, disk, tube, and cone objects (center, size, subdivision count, normal, vertices, radius, node/radius data, axis, length, volume)
+- Added primitive geometry queries: `getPatchCenter()`, `getPatchSize()`, `getTriangleVertex()`, `getVoxelCenter()`, `getVoxelSize()`, `getPatchCount()`, `getTriangleCount()`, `getPrimitiveBoundingBox()` (single UUID or list)
+- Added `setPrimitiveColor()` for mutating the color of one primitive or a list of primitives, accepting either `RGBcolor` or `RGBAcolor`
+- Added `clearPrimitiveData()` and `listPrimitiveData()` for removing and inspecting per-primitive data fields
+- Added domain cropping: `cropDomainX()`, `cropDomainY()`, `cropDomainZ()`, and `cropDomain()` to restrict all primitives (or a supplied UUID list) to given XYZ bounds
+
 # [v0.1.18] 2026-03-18
 
 - Updated helios-core to v1.3.70

docs/plugin_plantarchitecture.md

@@ -728,12 +728,14 @@ PlantArchitecture provides comprehensive file I/O capabilities to save and load
 
 ### Overview
 
-Four file I/O methods are available:
+The following file I/O methods are available:
 
 1. **`writePlantStructureXML()`**: Save complete plant structure to XML for later loading
 2. **`readPlantStructureXML()`**: Load saved plant structures from XML files
 3. **`writePlantMeshVertices()`**: Export all mesh vertices for external processing
 4. **`writeQSMCylinderFile()`**: Export to TreeQSM format for biomechanical analysis
+5. **`writePlantStructureUSD()`**: Export plant structure as a USD articulated rigid body for NVIDIA IsaacSim physics simulation
+6. **`registerGrowthFrame()`** / **`writePlantGrowthUSD()`** / **`clearGrowthFrames()`** / **`getGrowthFrameCount()`**: Capture and export per-step growth snapshots as a time-sampled USD animation file (importable into Blender)
 
 All methods work with both string paths and `pathlib.Path` objects, and correctly handle relative/absolute paths.
 
@@ -887,6 +889,66 @@ The exported file contains tab-separated values with the following information f
 - Tree architecture studies
 - Integration with TreeQSM analysis tools
 
+### Export USD Articulated Rigid Body (IsaacSim Physics)
+
+Export the plant structure as a PhysX articulation in USDA (ASCII USD) format for NVIDIA IsaacSim physics simulation. Each tube segment becomes a capsule-shaped rigid link connected by spherical joints whose local frames encode the rest-pose orientation. Spring/damper drives are derived from beam bending stiffness (`K = E*I/L`). Leaves, fruits, and flowers are represented as mass bodies attached by spring links.
+
+**Basic Usage:**
+
+```python
+from pyhelios import Context, PlantArchitecture
+from pyhelios.types import *
+
+with Context() as context:
+    with PlantArchitecture(context) as plantarch:
+        plantarch.loadPlantModelFromLibrary("almond")
+        plant_id = plantarch.buildPlantInstanceFromLibrary(vec3(0, 0, 0), age=50.0)
+
+        # Default physics parameters
+        plantarch.writePlantStructureUSD(plant_id, "almond.usda")
+
+        # Custom physics parameters
+        plantarch.writePlantStructureUSD(
+            plant_id, "almond_custom.usda",
+            elastic_modulus=8e9,         # Young's modulus (Pa)
+            wood_density=750.0,          # kg/m^3
+            damping_ratio=0.15,
+            leaf_mass_per_area=0.04,     # kg/m^2
+            fruit_mass=0.005,            # kg
+        )
+```
+
+### Growth Animation Export (USD for Blender)
+
+Capture per-step plant geometry snapshots during a growth simulation and export them as a time-sampled USDA animation that imports directly into Blender. Organs that appear during growth are toggled visible at the appropriate frame.
+
+**Basic Usage:**
+
+```python
+from pyhelios import Context, PlantArchitecture
+from pyhelios.types import *
+
+with Context() as context:
+    with PlantArchitecture(context) as plantarch:
+        plantarch.loadPlantModelFromLibrary("bean")
+        plant_id = plantarch.buildPlantInstanceFromLibrary(vec3(0, 0, 0), age=5.0)
+
+        # Capture a frame after each growth step
+        for _ in range(10):
+            plantarch.advanceTime(2.0)
+            plantarch.registerGrowthFrame(plant_id)
+
+        print(f"Captured {plantarch.getGrowthFrameCount(plant_id)} frames")
+
+        # Export as a 1-second-per-frame animation
+        plantarch.writePlantGrowthUSD(plant_id, "bean_growth.usda", seconds_per_frame=1.0)
+
+        # Reset frame storage when done
+        plantarch.clearGrowthFrames(plant_id)
+```
+
+This export is visual-only — no physics prims, joints, or collision shapes are written. For physics simulation, use `writePlantStructureUSD()` instead.
+
 ### Path Handling
 
 All file I/O methods accept both string paths and `pathlib.Path` objects, and correctly handle relative/absolute paths while preserving the user's working directory.

helios-core

@@ -1672,6 +1672,25 @@ PYHELIOS_API void getDate(helios::Context* context, int* day, int* month, int* y
 PYHELIOS_API void addTimeseriesData(helios::Context* context, const char* label, float value,
                                      int day, int month, int year, int hour, int minute, int second);
 
+/**
+ * @brief Update the value of an existing timeseries data point
+ * @param context Pointer to the Context
+ * @param label Name of the timeseries variable
+ * @param day Day of month (1-31) of the existing point
+ * @param month Month (1-12) of the existing point
+ * @param year Year of the existing point
+ * @param hour Hour of day (0-23) of the existing point
+ * @param minute Minute of hour (0-59) of the existing point
+ * @param second Second of minute (0-59) of the existing point
+ * @param new_value Replacement value to assign at the specified timestamp
+ *
+ * Throws a runtime error if the variable does not exist or if no point with the
+ * specified (date, time) is found. Use addTimeseriesData() to append a new point.
+ */
+PYHELIOS_API void updateTimeseriesData(helios::Context* context, const char* label,
+                                        int day, int month, int year, int hour, int minute, int second,
+                                        float new_value);
+
 /**
  * @brief Set the Context date and time from a timeseries data point index
  * @param context Pointer to the Context
@@ -2147,6 +2166,89 @@ PYHELIOS_API unsigned int* filterPrimitivesByDataFloat(helios::Context* context,
 PYHELIOS_API unsigned int* filterPrimitivesByDataInt(helios::Context* context, unsigned int* uuids, unsigned int count, const char* label, int value, const char* comparator, unsigned int* result_count);
 PYHELIOS_API unsigned int* filterPrimitivesByDataString(helios::Context* context, unsigned int* uuids, unsigned int count, const char* label, const char* value, unsigned int* result_count);
 
+// ==================== Object Geometry Queries ====================
+PYHELIOS_API unsigned int getObjectType(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getObjectCenter(helios::Context* context, unsigned int objID);
+PYHELIOS_API void getObjectBoundingBox(helios::Context* context, unsigned int objID, float* min_corner, float* max_corner);
+PYHELIOS_API void getObjectBoundingBox_batch(helios::Context* context, unsigned int* objIDs, unsigned int count, float* min_corner, float* max_corner);
+PYHELIOS_API unsigned int* getObjectPrimitiveUUIDs_batch(helios::Context* context, unsigned int* objIDs, unsigned int count, unsigned int* size);
+PYHELIOS_API unsigned int* getObjectPrimitiveUUIDs_nested(helios::Context* context, unsigned int* flat_objIDs, unsigned int* inner_counts, unsigned int outer_count, unsigned int* size);
+
+// Tile
+PYHELIOS_API float getTileObjectAreaRatio(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getTileObjectAreaRatio_batch(helios::Context* context, unsigned int* objIDs, unsigned int count, unsigned int* size);
+PYHELIOS_API float* getTileObjectCenter(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getTileObjectSize(helios::Context* context, unsigned int objID);
+PYHELIOS_API int* getTileObjectSubdivisionCount(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getTileObjectNormal(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getTileObjectTextureUV(helios::Context* context, unsigned int objID, unsigned int* size);
+PYHELIOS_API float* getTileObjectVertices(helios::Context* context, unsigned int objID, unsigned int* size);
+
+// Sphere
+PYHELIOS_API float* getSphereObjectCenter(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getSphereObjectRadius(helios::Context* context, unsigned int objID);
+PYHELIOS_API unsigned int getSphereObjectSubdivisionCount(helios::Context* context, unsigned int objID);
+PYHELIOS_API float getSphereObjectVolume(helios::Context* context, unsigned int objID);
+
+// Box
+PYHELIOS_API float* getBoxObjectCenter(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getBoxObjectSize(helios::Context* context, unsigned int objID);
+PYHELIOS_API int* getBoxObjectSubdivisionCount(helios::Context* context, unsigned int objID);
+PYHELIOS_API float getBoxObjectVolume(helios::Context* context, unsigned int objID);
+
+// Disk
+PYHELIOS_API float* getDiskObjectCenter(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getDiskObjectSize(helios::Context* context, unsigned int objID);
+PYHELIOS_API unsigned int getDiskObjectSubdivisionCount(helios::Context* context, unsigned int objID);
+
+// Tube
+PYHELIOS_API unsigned int getTubeObjectSubdivisionCount(helios::Context* context, unsigned int objID);
+PYHELIOS_API unsigned int getTubeObjectNodeCount(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getTubeObjectNodes(helios::Context* context, unsigned int objID, unsigned int* size);
+PYHELIOS_API float* getTubeObjectNodeRadii(helios::Context* context, unsigned int objID, unsigned int* size);
+PYHELIOS_API float* getTubeObjectNodeColors(helios::Context* context, unsigned int objID, unsigned int* size);
+PYHELIOS_API float getTubeObjectVolume(helios::Context* context, unsigned int objID);
+PYHELIOS_API float getTubeObjectSegmentVolume(helios::Context* context, unsigned int objID, unsigned int segment_index);
+
+// Cone
+PYHELIOS_API unsigned int getConeObjectSubdivisionCount(helios::Context* context, unsigned int objID);
+PYHELIOS_API float* getConeObjectNodes(helios::Context* context, unsigned int objID, unsigned int* size);
+PYHELIOS_API float* getConeObjectNodeRadii(helios::Context* context, unsigned int objID, unsigned int* size);
+PYHELIOS_API float* getConeObjectNode(helios::Context* context, unsigned int objID, int number);
+PYHELIOS_API float getConeObjectNodeRadius(helios::Context* context, unsigned int objID, int number);
+PYHELIOS_API float* getConeObjectAxisUnitVector(helios::Context* context, unsigned int objID);
+PYHELIOS_API float getConeObjectLength(helios::Context* context, unsigned int objID);
+PYHELIOS_API float getConeObjectVolume(helios::Context* context, unsigned int objID);
+
+// ==================== Primitive Geometry Queries ====================
+PYHELIOS_API float* getPatchCenter(helios::Context* context, unsigned int uuid);
+PYHELIOS_API float* getPatchSize(helios::Context* context, unsigned int uuid);
+PYHELIOS_API float* getTriangleVertex(helios::Context* context, unsigned int uuid, unsigned int number);
+PYHELIOS_API float* getVoxelCenter(helios::Context* context, unsigned int uuid);
+PYHELIOS_API float* getVoxelSize(helios::Context* context, unsigned int uuid);
+PYHELIOS_API unsigned int getPatchCount(helios::Context* context, bool include_hidden);
+PYHELIOS_API unsigned int getTriangleCount(helios::Context* context, bool include_hidden);
+PYHELIOS_API void getPrimitiveBoundingBox(helios::Context* context, unsigned int uuid, float* min_corner, float* max_corner);
+PYHELIOS_API void getPrimitiveBoundingBox_batch(helios::Context* context, unsigned int* uuids, unsigned int count, float* min_corner, float* max_corner);
+
+// ==================== Primitive Color Mutation ====================
+PYHELIOS_API void setPrimitiveColor(helios::Context* context, unsigned int uuid, float* color);
+PYHELIOS_API void setPrimitiveColor_batch(helios::Context* context, unsigned int* uuids, unsigned int count, float* color);
+PYHELIOS_API void setPrimitiveColorRGBA(helios::Context* context, unsigned int uuid, float* color);
+PYHELIOS_API void setPrimitiveColorRGBA_batch(helios::Context* context, unsigned int* uuids, unsigned int count, float* color);
+
+// ==================== Primitive Data Introspection / Cleanup ====================
+PYHELIOS_API void clearPrimitiveDataByLabel(helios::Context* context, unsigned int uuid, const char* label);
+PYHELIOS_API void clearPrimitiveDataByLabel_batch(helios::Context* context, unsigned int* uuids, unsigned int count, const char* label);
+PYHELIOS_API const char** listPrimitiveData(helios::Context* context, unsigned int uuid, unsigned int* count);
+
+// ==================== Domain Cropping ====================
+PYHELIOS_API void cropDomainX(helios::Context* context, float* xbounds);
+PYHELIOS_API void cropDomainY(helios::Context* context, float* ybounds);
+PYHELIOS_API void cropDomainZ(helios::Context* context, float* zbounds);
+PYHELIOS_API void cropDomainXYZ(helios::Context* context, float* xbounds, float* ybounds, float* zbounds);
+PYHELIOS_API unsigned int* cropDomainByUUIDs(helios::Context* context, unsigned int* uuids, unsigned int count, float* xbounds, float* ybounds, float* zbounds, unsigned int* out_size);
+
 #ifdef __cplusplus
 }
 #endif

native/include/pyhelios_wrapper_context.h

@@ -54,6 +54,16 @@ PYHELIOS_API unsigned int* getPlantCollisionRelevantObjectIDs(PlantArchitecture*
 PYHELIOS_API int writePlantMeshVertices(PlantArchitecture* plantarch, unsigned int plantID, const char* filename);
 PYHELIOS_API int writePlantStructureXML(PlantArchitecture* plantarch, unsigned int plantID, const char* filename);
 PYHELIOS_API int writeQSMCylinderFile(PlantArchitecture* plantarch, unsigned int plantID, const char* filename);
+PYHELIOS_API int writePlantStructureUSD(PlantArchitecture* plantarch, unsigned int plantID, const char* filename,
+                                         float elastic_modulus, float wood_density, float damping_ratio,
+                                         float static_friction, float dynamic_friction, float restitution,
+                                         float organ_spring_stiffness, float organ_spring_damping,
+                                         float leaf_mass_per_area, float fruit_mass, float flower_mass,
+                                         unsigned int solver_position_iterations, float min_segment_length);
+PYHELIOS_API int registerGrowthFrame(PlantArchitecture* plantarch, unsigned int plantID, float min_segment_length);
+PYHELIOS_API int writePlantGrowthUSD(PlantArchitecture* plantarch, unsigned int plantID, const char* filename, float seconds_per_frame);
+PYHELIOS_API int clearGrowthFrames(PlantArchitecture* plantarch, unsigned int plantID);
+PYHELIOS_API unsigned int getGrowthFrameCount(PlantArchitecture* plantarch, unsigned int plantID);
 PYHELIOS_API int readPlantStructureXML(PlantArchitecture* plantarch, const char* filename, bool quiet, unsigned int** plant_ids, int* num_plants);
 
 // Parameter management functions