Refactor image mesh processing and background removal functionality

- Updated NODE_GROUP_NAME from "O Refine DA3 Surface" to "O DA3 Surface".
- Introduced `remove_surface_background` function to filter out background faces and compact geometry.
- Enhanced `build_image_mesh` to conditionally remove background faces based on a new property.
- Added `snapform_remove_background` and `snapform_keep_original` properties to operators for better control over background handling.
- Updated UI to reflect new properties and improved resolution scaling logic.
- Refactored tests to cover new background removal functionality and ensure proper geometry handling.
- Adjusted geometry nodes and validation scripts to remove references to background handling.

src/snapform/worker.py

@@ -473,6 +473,12 @@ def export_prediction_attributes(prediction, output_directory):
     return output_path
 
 
+def remove_background_faces(faces, foreground_mask):
+    """Return only triangles whose vertices all belong to the foreground."""
+    foreground_points = foreground_mask.reshape(-1)
+    return faces[foreground_points[faces].all(axis=1)]
+
+
 def export_image_mesh_data(
     prediction,
     image_path,
@@ -505,9 +511,9 @@ def export_image_mesh_data(
     raw_depth = depth_frames[0]
     confidence = confidence_frames[0]
     intrinsics = np.asarray(prediction.intrinsics[0], dtype=np.float32)
-    progress(2, "Unprojecting camera geometry")
+    progress(2, "Unprojecting the depth grid")
     points = unproject_camera_depth(raw_depth, intrinsics)
-    progress(3, "Preparing DA3 and BEN2 attributes")
+    progress(3, "Preparing confidence and background data")
     foreground_mask = np.ones(raw_depth.shape, dtype=bool)
     if foreground_path is not None:
         foreground_mask = foreground_mesh_mask(
@@ -518,7 +524,7 @@ def export_image_mesh_data(
         raw_depth,
         confidence,
     )
-    progress(4, "Building editable source topology")
+    progress(4, "Building source triangles")
     faces = mesh_triangle_faces(
         points,
         raw_depth,
@@ -527,11 +533,13 @@ def export_image_mesh_data(
         False,
         0.0,
     )
+    if foreground_path is not None:
+        faces = remove_background_faces(faces, foreground_mask)
     if not len(faces):
         raise ValueError(
             "DA3 output does not contain any valid surface faces"
         )
-    progress(5, "Projecting UV and structured attributes")
+    progress(5, "Preparing source UV and attributes")
     vertices, faces = compact_mesh(
         points.reshape(-1, 3),
         faces,
@@ -551,7 +559,7 @@ def export_image_mesh_data(
     reference_depth = float(np.median(valid_depth))
     output_directory = Path(output_directory)
     output_directory.mkdir(parents=True, exist_ok=True)
-    progress(6, "Writing surface data")
+    progress(6, "Writing source surface data")
     result_path = output_directory / "mesh.npz"
     np.savez_compressed(
         result_path,
@@ -564,7 +572,8 @@ def export_image_mesh_data(
         **attributes,
     )
     texture_path = output_directory / "texture.png"
-    with Image.open(image_path) as image:
+    texture_source = foreground_path or image_path
+    with Image.open(texture_source) as image:
         image.convert("RGBA").save(texture_path, format="PNG", compress_level=1)
     return result_path, texture_path
 
@@ -1650,7 +1659,7 @@ def reconstruct(args, model_cache=None, cancel_check=None):
                 write_status(
                     args.status,
                     0.88 + 0.09 * step / total,
-                    f"Post-processing {step}/{total}: {label}",
+                    f"Preparing surface data {step}/{total}: {label}",
                 )
 
             export_image_mesh_data(