Wrong instance segmentation map with many objects

[s70c3]

Hi! Thanks for the awesome blender util!

I use your util to create a segmentation map for bunch of clumped objects created with instances and geocodes. I realized before creating instance map and reassigned with data.copy(). The problem is that I have more than 100 objects on area, but some objects still have the same color on instance map, limited to 20-30. I used a lot of attempts to change inst_id, but situation stayed the same. How can I fix it?

Here is the code (some hacks was used to work with material, so code is not perfect)

for img_num in range(1):
    # remove all MESH objects
    bpy.ops.wm.read_homefile()
    update_camera(bpy.data.objects['Camera'])
    update_light(bpy.data.objects['Light'])
    with bpy.data.libraries.load('rocks.blend') as (data_from, data_to):
        data_to.collections = data_from.collections
    with bpy.data.libraries.load('froth_gm.blend') as (data_from, data_to):
        data_to.materials = data_from.materials
    

    # bpy.ops.mesh.primitive_cube_add(size=1, location=(0,0,0))
    cube =  bpy.data.objects.get('Cube')
    
    modifier=cube.modifiers.new("Bubbles", "NODES")
    modifier.node_group = geometry_nodes_node_group1(seed=(2,4, 3), dists=(70.0, 50.0, 50))
    
    for scene in bpy.data.scenes:
      scene.cycles.device = 'GPU'

    prefs = bpy.context.preferences
    cprefs = prefs.addons['cycles'].preferences
    bpy.context.scene.render.engine = 'CYCLES'
    bpy.context.preferences.addons[
        "cycles"
    ].preferences.compute_device_type = "CUDA" # or "OPENCL"
    # bpy.context.scene.cycles.samples = 32
    # Set the device and feature set
    bpy.context.scene.cycles.device = "GPU"
    
    result = bpycv.render_data()
    # save result
    cv2.imwrite(
        f"img{img_num}.jpg", result["image"][..., ::-1]
    )  # transfer RGB image to opencv's BGR
    
    # modifier=cube.modifiers.new("Bubbles", "NODES")
    modifier.node_group = geometry_nodes_node_group2(seed=(2, 4, 3),  dists=(70.0, 50.0, 50))
    
    cube.select_set(True)
    bpy.context.view_layer.objects.active = cube
    bpy.ops.object.mode_set(mode='OBJECT')
    bpy.ops.object.mode_set(mode='EDIT')
    bpy.ops.mesh.select_all(action='SELECT')
    bpy.ops.object.mode_set(mode='OBJECT')
    bpy.ops.object.duplicates_make_real()
    
    for i, o in enumerate(bpy.data.objects):
        if o.type in ("MESH", "CURVE"):
            o.data=o.data.copy()
            o["inst_id"] = randint(1, 8)*1000+i
   
    bpy.context.scene.render.engine = 'BLENDER_EEVEE'

    bpy.context.scene.render.resolution_y = 512
    bpy.context.scene.render.resolution_x = 512
    
    bpy.context.view_layer.cycles.use_denoising = True
    bpy.context.view_layer.cycles.denoising_store_passes = True
    bpy.context.scene.cycles.samples = 200
    # Set the device and feature set
    bpy.context.scene.cycles.device = "GPU"
    
    result = bpycv.render_data(render_image=False)
    objs = {
                obj.name: obj for obj in bpy.data.objects if obj.type in ("MESH", "CURVE")
            }
    
    print(len(objs))
    cv2.imwrite(f"mask{img_num}.png", np.uint16(result["inst"]))
    cv2.imwrite(f"demo-vis{img_num}.jpg", result.vis()[..., ::-1])

Here are the examples of render and instance map.