Trellis generating duplicate inner mesh walls

[firesightstudios]

Most generations add an entire inner shell of the mesh.

I was able to create a function in blender that can 99% remove the inner shell but results in some random issues

Stats on Model post Trellis2 Generation at 1024 Resolution and 2048 Texture Size

POST TRELLIS 2 Generation:

Post Healing Script - Removing Inner Walls:

Blender 5.1.0
Base Blender Script used:

import bpy
import bmesh
from mathutils.bvhtree import BVHTree

class GeometryAlgorithm:
    Mathematical targeted healing of AI mesh anomalies.

    @staticmethod
    def heal_geometry(obj):
        if bpy.context.active_object and bpy.context.active_object.mode != 'OBJECT':
            bpy.ops.object.mode_set(mode='OBJECT')

        bpy.ops.object.select_all(action='DESELECT')
        obj.hide_set(False)
        obj.select_set(True)
        bpy.context.view_layer.objects.active = obj

        # 1. Apply Transforms (Crucial for Mixamo auto-rigger)
        bpy.ops.object.transform_apply(location=False, rotation=True, scale=True)
        bpy.ops.mesh.customdata_custom_splitnormals_clear()

        bpy.ops.object.mode_set(mode='EDIT')


        # ==========================================
        # --- PASS 1: LINE-OF-SIGHT SEED & SPREAD ---
        # ==========================================
        bm = bmesh.from_edit_mesh(obj.data)
        bm.faces.ensure_lookup_table()
        
        # Deselect everything to prepare for seeding
        for f in bm.faces:
            f.select = False

        verts_co = [v.co for v in bm.verts]
        faces_indices = [[v.index for v in f.verts] for f in bm.faces]
        tree = BVHTree.FromPolygons(verts_co, faces_indices)

        seed_count = 0
        
        # 1. Raycast Seed: If a face's normal points directly at the sky, it's 100% outer shell.
        for f in bm.faces:
            # Nudge the origin slightly to prevent hitting the face itself
            origin = f.calc_center_median() + (f.normal * 0.0001)
            loc, _, _, _ = tree.ray_cast(origin, f.normal)
            
            if loc is None:
                f.select = True
                seed_count += 1
                
        # 2. Extreme Bounds Seed: An absolute guarantee to find the outer limits of the mesh
        if bm.verts:
            extremes = [
                min(bm.verts, key=lambda v: v.co.z), max(bm.verts, key=lambda v: v.co.z),
                min(bm.verts, key=lambda v: v.co.x), max(bm.verts, key=lambda v: v.co.x),
                min(bm.verts, key=lambda v: v.co.y), max(bm.verts, key=lambda v: v.co.y)
            ]
            for v in extremes:
                for f in v.link_faces:
                    if not f.select:
                        f.select = True
                        seed_count += 1

        bmesh.update_edit_mesh(obj.data)

        if seed_count > 0:
            # 3. The Spread: Select everything connected to the outer shell seeds!
            # This perfectly protects backpacks, deep armpits, and tight crevices.
            bpy.ops.mesh.select_linked()
            
            # 4. The Purge: Delete everything that is detached/inside (The Phantom Inner Wall)
            bpy.ops.mesh.select_all(action='INVERT')
            bpy.ops.mesh.delete(type='FACE')


        # ==========================================
        # --- PASS 2: SURGICAL BMESH STRAY EDGE SNIP ---
        # ==========================================
        # Re-initialize bmesh after the face deletion
        bm = bmesh.from_edit_mesh(obj.data)
        for _ in range(2):
            bm.edges.ensure_lookup_table()
            bm.verts.ensure_lookup_table()
            
            stray_edges = [e for e in bm.edges if len(e.link_faces) == 0]
            if stray_edges:
                bmesh.ops.delete(bm, geom=stray_edges, context='EDGES')

            stray_verts = [v for v in bm.verts if len(v.link_faces) == 0]
            if stray_verts:
                bmesh.ops.delete(bm, geom=stray_verts, context='VERTS')
                
        bmesh.update_edit_mesh(obj.data)


        # ==========================================
        # --- PASS 3: SAFE MACRO GEOMETRY HEALING ---
        # ==========================================
        for _ in range(3):
            bpy.ops.mesh.select_all(action='SELECT')
            
            # Since the phantom inner shell was vaporized, it is now 
            # 100% safe to run the vertex merge without the walls pinching together!
            bpy.ops.mesh.remove_doubles(threshold=0.0005)

            # Blender's native interior face selector handles any remaining micro-webbing
            bpy.ops.mesh.select_all(action='DESELECT')
            bpy.ops.mesh.select_interior_faces()
            bpy.ops.mesh.delete(type='FACE')

            # Instantly bridges any holes shut left by the purge.
            bpy.ops.mesh.select_all(action='SELECT')
            bpy.ops.mesh.fill_holes(sides=100)


        # ==========================================
        # --- PASS 4: DEGENERATE FACE CLEANUP ---
        # ==========================================
        bpy.ops.mesh.select_all(action='SELECT')
        bpy.ops.mesh.delete_loose()
        
        # Safely eliminates the 88k micro-faces AI tools generate
        bpy.ops.mesh.select_all(action='SELECT')
        bpy.ops.mesh.dissolve_degenerate(threshold=0.002)

        # Force all normals outward to fix Mixamo voxelizer holes
        bpy.ops.mesh.select_all(action='SELECT')
        bpy.ops.mesh.normals_make_consistent(inside=False)


        # ==========================================
        # --- CLEANUP ---
        # ==========================================
        try:
            bpy.ops.object.mode_set(mode='SCULPT')
            bpy.ops.paint.mask_clear()
        except Exception:
            pass

        bpy.ops.object.mode_set(mode='OBJECT')