Problem with pytorch3d lighting when rendering a 3d mesh

Question

I'm trying to render a 3d mesh from 11 point of views, but I get images where the mesh is not lighted like or with a non-white background, just like these ones: not lighted mesh partly lighted mesh but with a non-white background

I tried to calculate the light location from the camera's location using R and T so that i can ensure that the camera position change, the light will follow, but its gives 3 good images from 11. This is my settings:

# I go throw theses parameters with a loop to execute the next block
elev: [0, 60, 120, 180, 240, 300],
azim: [60, 120, 180, 240, 300],

# For the third coordinate of the light position I took z equal to the camera distance of the object and tried to calculate x and y from R and T.

z= camera_dist

# Initialize the camera with camera distance, elevation, and azimuth angle
                    R, T = look_at_view_transform(dist, elev = eleva, azim = azimu)

                    cameras = FoVPerspectiveCameras(device=device, R=R, T=T, znear=1.5, zfar=10.0, fov=75.0)
                    
                    # Extract translation vector and rotation matrix components
                    
                    # Convert T to a 2D tensor
                    T = T.view(1, 3)
                    # Extract the translation vector
                    translation = -T[:, :3]
                    # Invert the rotation matrix
                    R_inv = R[:, :3, :3].transpose(1, 2)
                    # Calculate the camera location in world coordinates
                    camera_location = torch.matmul(R_inv, translation.unsqueeze(-1)).squeeze(-1)
                    # Extract x and y
                    x, y= camera_location[0, :2].tolist() # Adjusted to get the values from the tensor
                    print(f"Camera Location: x={x}, y={y}, z={z}")
                    
                    lights = PointLights(
                    device=cameras.device,
                    # location=center + torch.tensor([R, T, light_distance], dtype=torch.float32)[None, :],
                    location = [[x, y, z]],
                    diffuse_color=torch.tensor([[1.0, 1.0, 1.0]], dtype=torch.float32),
                    )

                    # Initialize rasterizer by using a MeshRasterizer class
                    rasterizer = MeshRasterizer(
                        cameras=cameras, raster_settings=raster_settings )

                    # éclaircir la mesh
                    # Place a point light in front of the object. As mentioned above, the front of the mesh is facing the
                    # -z direction.

                    # The textured phong shader interpolates the texture uv coordinates for
                    # each vertex, and samples from a texture image.
                    # shader = SoftSilhouetteShader( device = device,cameras = cameras, materials=materials, lights=lights)
                    shader = HardFlatShader(device = device, cameras = cameras, materials=materials, lights=lights )

                    # Create a mesh renderer by composing a rasterizer and a shader
                    renderer = MeshRenderer(rasterizer, shader)

do you have any suggestions?