fix(paint3d): soft bake erosion, boundary smoothing and wider angle threshold

Replace hard binary erosion with soft gradient (kernel normalized conv2d instead of threshold). Fix boundary_map tensor shape (was 1D, now 3D matching cos_map). Add Gaussian-blur boundary weight softening in bake_from_multiview. Raise bake_angle_thres from 75 to 85 degrees for wider view coverage.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

Author: maikramer

Paint3D/src/paint3d/hy3dpaint/DifferentiableRenderer/MeshRender.py

@@ -376,7 +376,7 @@ def __init__(
         self.use_antialias = use_antialias
         self.max_mip_level = max_mip_level
         self.filter_mode = filter_mode
-        self.bake_angle_thres = 75
+        self.bake_angle_thres = 85
         self.set_boundary_unreliable_scale(2)
         self.bake_mode = bake_mode
         self.shader_type = shader_type
@@ -1226,19 +1226,21 @@ def back_project(self, image, elev, azim, camera_distance=None, center=None, met
         if self.bake_unreliable_kernel_size > 0:
             kernel_size = self.bake_unreliable_kernel_size * 2 + 1
             kernel = torch.ones((1, 1, kernel_size, kernel_size), dtype=torch.float32).to(sketch_image.device)
+            kernel_norm = kernel / kernel.sum()
 
             visible_mask = visible_mask.permute(2, 0, 1).unsqueeze(0).float()
-            visible_mask = F.conv2d(1.0 - visible_mask, kernel, padding=kernel_size // 2)
-            visible_mask = 1.0 - (visible_mask > 0).float()  # 二值化
+            outside_proximity = F.conv2d(1.0 - visible_mask, kernel_norm, padding=kernel_size // 2)
+            visible_mask = (1.0 - outside_proximity).clamp(0, 1)
             visible_mask = visible_mask.squeeze(0).permute(1, 2, 0)
 
             sketch_image = sketch_image.permute(2, 0, 1).unsqueeze(0)
-            sketch_image = F.conv2d(sketch_image, kernel, padding=kernel_size // 2)
-            sketch_image = (sketch_image > 0).float()  # 二值化
+            edge_proximity = F.conv2d(sketch_image, kernel_norm, padding=kernel_size // 2)
+            sketch_image = (1.0 - edge_proximity).clamp(0, 1)
             sketch_image = sketch_image.squeeze(0).permute(1, 2, 0)
-            visible_mask = visible_mask * (sketch_image < 0.5)
 
-        cos_image[visible_mask == 0] = 0
+            visible_mask = visible_mask * sketch_image
+
+        cos_image = cos_image * visible_mask
 
         method = self.bake_mode if method is None else method
 
@@ -1337,6 +1339,7 @@ def back_project(self, image, elev, azim, camera_distance=None, center=None, met
 
             texture = texture.view(self.texture_size[0], self.texture_size[1], channel)
             cos_map = cos_map.view(self.texture_size[0], self.texture_size[1], 1)
+            boundary_map = boundary_map.view(self.texture_size[0], self.texture_size[1], 1)
             # texture = torch.clamp(texture,0,1)
 
         else:

Paint3D/src/paint3d/hy3dpaint/utils/pipeline_utils.py

@@ -111,13 +111,25 @@ def bake_from_multiview(self, views, camera_elevs, camera_azims, view_weights):
         project_textures, project_weighted_cos_maps = [], []
         project_boundary_maps = []
 
+        blur_radius = 5
+        _blur_k = torch.ones(1, 1, blur_radius, blur_radius, device="cuda") / (blur_radius * blur_radius)
+
         for view, camera_elev, camera_azim, weight in zip(
             views, camera_elevs, camera_azims, view_weights, strict=False
         ):
             project_texture, project_cos_map, project_boundary_map = self.render.back_project(
                 view, camera_elev, camera_azim
             )
             project_cos_map = weight * (project_cos_map**self.config.bake_exp)
+
+            bm_blurred = torch.nn.functional.conv2d(
+                project_boundary_map.permute(2, 0, 1).unsqueeze(0),
+                _blur_k.to(project_boundary_map.device),
+                padding=blur_radius // 2,
+            ).squeeze(0).permute(1, 2, 0)
+            soft_factor = (1.0 - 0.5 * bm_blurred.clamp(0, 1)).clamp(min=0.0)
+            project_cos_map = project_cos_map * soft_factor
+
             project_textures.append(project_texture)
             project_weighted_cos_maps.append(project_cos_map)
             project_boundary_maps.append(project_boundary_map)