The Nitros depth subscriber is incorrectly configured

[abertino-cpmfg]

According to depthImageFromNitrosViewAsync (line 140 of image_conversions.cpp), depth images should be in either float32 or uint16 format. However, the nitros subscriber is incorrectly configured to only accept rbg8 images, leading to type negotiation failing and a fallback to cpu-based messaging. Line 254 of nvblox_node.cpp creates the subscription without specifying a compatible type, leading the message filter to select it based on MessageType::GetDefaultCompatibleFormat(), which is rgb8 for images. Thus, the subscriber negotiates expecting a color image, fails, and falls back to using a standard ros2 subscription.

Here is the relevant section in image_conversions.cpp

bool depthImageFromNitrosViewAsync(
  const NitrosView & view, DepthImage * depth_image,
  rclcpp::Logger logger, const CudaStream & cuda_stream)
{
  CHECK_NOTNULL(depth_image);

  if (view.GetEncoding() == "32FC1") {
    return depthFromFloatHostOrDeviceAsync(
      reinterpret_cast<const float *>(view.GetGpuData()),
      view.GetHeight(), view.GetWidth(), depth_image,
      cuda_stream);
  } else if (view.GetEncoding() == "16UC1" || view.GetEncoding() == "mono16") {
    return depthFromIntDeviceAsync(
      reinterpret_cast<const int16_t *>(view.GetGpuData()),
      view.GetHeight(), view.GetWidth(), depth_image, cuda_stream);
  } else {
    RCLCPP_ERROR_STREAM(logger, "Invalid depth image encoding: " << view.GetEncoding());
    return false;
  }
}

The relevant section in nvblox_node.cpp

depth_image_subs_.emplace_back(
        std::make_shared<nvidia::isaac_ros::nitros::message_filters::Subscriber<NitrosView>>(
          this, base_name_depth + "/image",
          input_qos_profile));

And the relevant sections in managed_nitros_message_filters_subscriber.hpp

Subscriber(
    NodeType * node, const std::string & topic,
    const rmw_qos_profile_t qos = rmw_qos_profile_default)
{
  subscribe(node, topic, qos);
}

void subscribe(
    NodeType * node, const std::string & topic,
    const rmw_qos_profile_t qos = rmw_qos_profile_default) override
{
  subscribe(node, topic, qos, rclcpp::SubscriptionOptions());
}

void subscribe(
    NodeType * node,
    const std::string & topic,
    const rmw_qos_profile_t qos,
    rclcpp::SubscriptionOptions options,
    const std::string & compatible_data_format = "",
    const NitrosDiagnosticsConfig & diagnostics_config = {})
{
  unsubscribe();

  if (!topic.empty()) {
    topic_ = topic;
    rclcpp::QoS rclcpp_qos(rclcpp::QoSInitialization::from_rmw(qos));
    rclcpp_qos.get_rmw_qos_profile() = qos;
    qos_ = qos;
    options_ = options;

    sub_ = std::make_shared<ManagedNitrosSubscriber<NitrosTypeViewT>>(
      node,
      topic,
      compatible_data_format !=
      "" ? compatible_data_format : MessageType::GetDefaultCompatibleFormat(),
      [this](const NitrosTypeViewT & nitrosViewMsg) {
        this->cb(EventType(std::make_shared<const MessageType>(nitrosViewMsg.GetMessage())));
      },
      diagnostics_config,
      rclcpp_qos
    );

    node_raw_ = node;
  }
}