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  3. Stereo tag detection: WARNING, apriltag roll/pitch out of bounds

Stereo tag detection: WARNING, apriltag roll/pitch out of bounds

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  • A afdrus

    The command voxl-vision-px4 -m detects properly the distances between camera and tag, as well as their orientation.
    Also voxl-vision-px4 -l shows the correct pose of the tag in local frame, however the warning keeps being there. These results lead me to think that there seems to be an issue in the relation with the fixed frame, however if I use the same config files and I simply change the detector from any stereo pipe to tracking everything works fine and WARNING, apriltag roll/pitch out of bounds is gone.

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    afdrus
    Regular
    wrote on last edited by
    #4

    Sorry to insist, but I am not able to move forward with this issue, can anyone help?

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    • ModeratorM Offline
      ModeratorM Offline
      Moderator
      ModalAI Team
      wrote on last edited by
      #5

      Can you please help with which version of software you are using? voxl-vision-px4 has been deprecated. Have you tried with the latest?

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      • ModeratorM Moderator

        Can you please help with which version of software you are using? voxl-vision-px4 has been deprecated. Have you tried with the latest?

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        afdrus
        Regular
        wrote on last edited by
        #6

        @Moderator Thank you for your reply, we are currently using voxl SDK 0.9.5. All the libraries that come with this SDK are up to date. I did not try with the latest version, but the bug should be easy to replicate with a stereo setup on a voxl2.

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        • ModeratorM Moderator

          Can you please help with which version of software you are using? voxl-vision-px4 has been deprecated. Have you tried with the latest?

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          afdrus
          Regular
          wrote on last edited by
          #7

          @Moderator I just tried the same with SDK 1.0.0 and the result is the same, can't understand which transformation is wrong, could the parameters in the extrinscs.conf be involved?

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          • A afdrus

            @Moderator I just tried the same with SDK 1.0.0 and the result is the same, can't understand which transformation is wrong, could the parameters in the extrinscs.conf be involved?

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            afdrus
            Regular
            wrote on last edited by
            #8

            @Moderator Any updates on this issue?

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            • A afdrus

              @Moderator Any updates on this issue?

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              afdrus
              Regular
              wrote on last edited by
              #9

              Nothing changed on v1.1.0

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              • A afdrus

                Nothing changed on v1.1.0

                ModeratorM Offline
                ModeratorM Offline
                Moderator
                ModalAI Team
                wrote on last edited by
                #10

                @afdrus since the stereo sensors have different orientation than tracking, did you change R_tag_to_fixed ?

                You can find that error in the source code at this link below. That should help you debug
                https://gitlab.com/voxl-public/voxl-sdk/services/voxl-vision-hub/-/blob/master/src/geometry.c?ref_type=heads#L613

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                • ModeratorM Moderator

                  @afdrus since the stereo sensors have different orientation than tracking, did you change R_tag_to_fixed ?

                  You can find that error in the source code at this link below. That should help you debug
                  https://gitlab.com/voxl-public/voxl-sdk/services/voxl-vision-hub/-/blob/master/src/geometry.c?ref_type=heads#L613

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                  afdrus
                  Regular
                  wrote on last edited by
                  #11

                  @Moderator Thank you for your response!
                  I thought that, as the name of the transformation suggest, R_tag_to_fixed did not depend on the orientation of the camera but rather on the orientation between the tag and fixed frame. I would expect to set the camera orientation in the extrinsics.conf file.

                  Hoever if I run voxl-vision-hub --debug_tag_local I get the following

                  ID  0 T_tag_wrt_local -4.74  2.63  0.89  Roll  1.45 Pitch  0.05 Yaw -2.14
                  WARNING, apriltag roll/pitch out of bounds
                  ID  0 T_tag_wrt_local -4.74  2.63  0.89  Roll  1.39 Pitch  0.04 Yaw -2.16
                  WARNING, apriltag roll/pitch out of bounds
                  ID  0 T_tag_wrt_local -4.73  2.63  0.89  Roll  1.32 Pitch  0.06 Yaw -2.08
                  ID  0 T_tag_wrt_local -4.74  2.63  0.89  Roll  1.40 Pitch  0.05 Yaw -2.13
                  ID  0 T_tag_wrt_local -4.74  2.64  0.89  Roll  1.40 Pitch  0.04 Yaw -2.14
                  

                  No matter what values I put in extrinsics.conf or in R_tag_to_fixed, the Roll keeps being around 1.4 radians

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                  • A afdrus

                    @Moderator Thank you for your response!
                    I thought that, as the name of the transformation suggest, R_tag_to_fixed did not depend on the orientation of the camera but rather on the orientation between the tag and fixed frame. I would expect to set the camera orientation in the extrinsics.conf file.

                    Hoever if I run voxl-vision-hub --debug_tag_local I get the following

                    ID  0 T_tag_wrt_local -4.74  2.63  0.89  Roll  1.45 Pitch  0.05 Yaw -2.14
                    WARNING, apriltag roll/pitch out of bounds
                    ID  0 T_tag_wrt_local -4.74  2.63  0.89  Roll  1.39 Pitch  0.04 Yaw -2.16
                    WARNING, apriltag roll/pitch out of bounds
                    ID  0 T_tag_wrt_local -4.73  2.63  0.89  Roll  1.32 Pitch  0.06 Yaw -2.08
                    ID  0 T_tag_wrt_local -4.74  2.63  0.89  Roll  1.40 Pitch  0.05 Yaw -2.13
                    ID  0 T_tag_wrt_local -4.74  2.64  0.89  Roll  1.40 Pitch  0.04 Yaw -2.14
                    

                    No matter what values I put in extrinsics.conf or in R_tag_to_fixed, the Roll keeps being around 1.4 radians

                    ModeratorM Offline
                    ModeratorM Offline
                    Moderator
                    ModalAI Team
                    wrote on last edited by
                    #12

                    @afdrus OK, you could be right. Hopefully the source code helps? We don't use it in this way, so you may need to modify

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                    • ModeratorM Moderator

                      @afdrus OK, you could be right. Hopefully the source code helps? We don't use it in this way, so you may need to modify

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                      afdrus
                      Regular
                      wrote on last edited by
                      #13

                      @Moderator Thanks to some prints I notice that the issue comes from R_cam_to_imu which always (and only) picks up the parameters from the tracking camera in extrinsics.conf. Regardless of the pipe specified in voxl-tag-detector.conf. Hope this insight might help you in solving the issue in future releases.

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                      • A afdrus

                        @Moderator Thanks to some prints I notice that the issue comes from R_cam_to_imu which always (and only) picks up the parameters from the tracking camera in extrinsics.conf. Regardless of the pipe specified in voxl-tag-detector.conf. Hope this insight might help you in solving the issue in future releases.

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                        afdrus
                        Regular
                        wrote on last edited by
                        #14

                        I did a very quick and dummy workaround to fix the problem, most of the changes are in geometry.c in the following snippet of code:

                        int geometry_calc_R_T_tag_in_local_frame(int64_t frame_timestamp_ns,
                        										 rc_matrix_t R_tag_to_cam, rc_vector_t T_tag_wrt_cam,
                        										 rc_matrix_t *R_tag_to_local, rc_vector_t *T_tag_wrt_local, char* input_pipe)
                        {
                        	// these "correct" values are from the past aligning to the timestamp
                        	static rc_matrix_t correct_R_imu_to_vio = RC_MATRIX_INITIALIZER;
                        	static rc_vector_t correct_T_imu_wrt_vio = RC_VECTOR_INITIALIZER;
                        
                        	int ret = rc_tf_ringbuf_get_tf_at_time(&vio_ringbuf,
                        										   frame_timestamp_ns,
                        										   &correct_R_imu_to_vio,
                        										   &correct_T_imu_wrt_vio);
                        
                        	// fail silently, on catastrophic failure the previous function would have
                        	// printed a message. If ret==-2 that's a soft failure meaning we just don't
                        	// have enough vio data yet, so also return silently.
                        	if (ret < 0)
                        		return -1;
                        
                        	pthread_mutex_lock(&tf_mutex);
                        
                        	// Read extrinsics parameters
                        	int n;
                        	vcc_extrinsic_t t[VCC_MAX_EXTRINSICS_IN_CONFIG];
                        	vcc_extrinsic_t tmp;
                        
                        	// now load in extrinsics
                        	if (vcc_read_extrinsic_conf_file(VCC_EXTRINSICS_PATH, t, &n, VCC_MAX_EXTRINSICS_IN_CONFIG))
                        	{
                        		return -1;
                        	}
                        
                        	// Initialize camera matrices
                        	rc_matrix_t R_cam_to_imu_tmp = RC_MATRIX_INITIALIZER;
                        	rc_matrix_t R_cam_to_body = RC_MATRIX_INITIALIZER;
                        	rc_vector_t T_cam_wrt_imu_tmp = RC_VECTOR_INITIALIZER;
                        	rc_vector_t T_cam_wrt_body = RC_VECTOR_INITIALIZER;
                        
                        	rc_vector_zeros(&T_cam_wrt_body, 3);
                        	rc_vector_zeros(&T_cam_wrt_imu_tmp, 3);
                        
                        	rc_matrix_identity(&R_cam_to_imu_tmp, 3);
                        	rc_matrix_identity(&R_cam_to_body, 3);
                        
                        	printf("input_pipe: %s \n", input_pipe);
                        
                        	if (strcmp(input_pipe, "stereo_front") == 0)
                        	{
                        		// Pick out IMU to Body. config.c already set this up for imu1 so just leave it as is
                        		if (vcc_find_extrinsic_in_array("body", "stereo_front_l", t, n, &tmp))
                        		{
                        			fprintf(stderr, "ERROR: %s missing body to stereo_front_l, sticking with identity for now\n", VCC_EXTRINSICS_PATH);
                        			return -1;
                        		}
                        		rc_rotation_matrix_from_tait_bryan(tmp.RPY_parent_to_child[0] * DEG_TO_RAD,
                        										   tmp.RPY_parent_to_child[1] * DEG_TO_RAD,
                        										   tmp.RPY_parent_to_child[2] * DEG_TO_RAD,
                        										   &R_cam_to_body);
                        		rc_vector_from_array(&T_cam_wrt_body, tmp.T_child_wrt_parent, 3);
                        		T_cam_wrt_imu_tmp.d[0] = T_cam_wrt_body.d[0] - T_imu_wrt_body.d[0];
                        		T_cam_wrt_imu_tmp.d[1] = T_cam_wrt_body.d[1] - T_imu_wrt_body.d[1];
                        		T_cam_wrt_imu_tmp.d[2] = T_cam_wrt_body.d[2] - T_imu_wrt_body.d[2];
                        
                        		rc_matrix_multiply(R_body_to_imu, R_cam_to_body, &R_cam_to_imu_tmp);
                        
                        		printf("RPY: \n%5.2f %5.2f %5.2f\n\n",
                        		tmp.RPY_parent_to_child[0], tmp.RPY_parent_to_child[1],tmp.RPY_parent_to_child[2]);
                        
                        		printf("R_cam_to_imu_tmp: \n%5.2f %5.2f %5.2f\n %5.2f %5.2f %5.2f\n %5.2f %5.2f %5.2f\n\n",
                        		R_cam_to_imu_tmp.d[0][0], R_cam_to_imu_tmp.d[0][1], R_cam_to_imu_tmp.d[0][2],
                        		R_cam_to_imu_tmp.d[1][0], R_cam_to_imu_tmp.d[1][1], R_cam_to_imu_tmp.d[1][2],
                        		R_cam_to_imu_tmp.d[2][0], R_cam_to_imu_tmp.d[2][1], R_cam_to_imu_tmp.d[2][2]);
                        
                        		// calculate position of tag wrt local
                        		rc_matrix_times_col_vec(R_cam_to_imu_tmp, T_tag_wrt_cam, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, T_cam_wrt_imu_tmp);
                        		rc_matrix_times_col_vec_inplace(correct_R_imu_to_vio, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, correct_T_imu_wrt_vio);
                        		rc_matrix_times_col_vec_inplace(R_vio_to_local, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, T_vio_ga_wrt_local);
                        
                        		// calculate rotation tag to local
                        		rc_matrix_multiply(R_cam_to_imu_tmp, R_tag_to_cam, R_tag_to_local);
                        		rc_matrix_left_multiply_inplace(correct_R_imu_to_vio, R_tag_to_local);
                        		rc_matrix_left_multiply_inplace(R_vio_to_local, R_tag_to_local);
                        	}
                        	else if (strcmp(input_pipe, "stereo_rear") == 0)
                        	{
                        		// Pick out IMU to Body. config.c already set this up for imu1 so just leave it as is
                        		if (vcc_find_extrinsic_in_array("body", "stereo_rear_l", t, n, &tmp))
                        		{
                        			fprintf(stderr, "ERROR: %s missing body to stereo_rear_l, sticking with identity for now\n", VCC_EXTRINSICS_PATH);
                        			return -1;
                        		}
                        		rc_rotation_matrix_from_tait_bryan(tmp.RPY_parent_to_child[0] * DEG_TO_RAD,
                        										   tmp.RPY_parent_to_child[1] * DEG_TO_RAD,
                        										   tmp.RPY_parent_to_child[2] * DEG_TO_RAD,
                        										   &R_cam_to_body);
                        		rc_vector_from_array(&T_cam_wrt_body, tmp.T_child_wrt_parent, 3);
                        		T_cam_wrt_imu_tmp.d[0] = T_cam_wrt_body.d[0] - T_imu_wrt_body.d[0];
                        		T_cam_wrt_imu_tmp.d[1] = T_cam_wrt_body.d[1] - T_imu_wrt_body.d[1];
                        		T_cam_wrt_imu_tmp.d[2] = T_cam_wrt_body.d[2] - T_imu_wrt_body.d[2];
                        
                        		rc_matrix_multiply(R_body_to_imu, R_cam_to_body, &R_cam_to_imu_tmp);
                        
                        		printf("R_cam_to_imu_tmp: \n%5.2f %5.2f %5.2f\n %5.2f %5.2f %5.2f\n %5.2f %5.2f %5.2f\n\n",
                        		R_cam_to_imu_tmp.d[0][0], R_cam_to_imu_tmp.d[0][1], R_cam_to_imu_tmp.d[0][2],
                        		R_cam_to_imu_tmp.d[1][0], R_cam_to_imu_tmp.d[1][1], R_cam_to_imu_tmp.d[1][2],
                        		R_cam_to_imu_tmp.d[2][0], R_cam_to_imu_tmp.d[2][1], R_cam_to_imu_tmp.d[2][2]);
                        
                        		// calculate position of tag wrt local
                        		rc_matrix_times_col_vec(R_cam_to_imu_tmp, T_tag_wrt_cam, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, T_cam_wrt_imu_tmp);
                        		rc_matrix_times_col_vec_inplace(correct_R_imu_to_vio, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, correct_T_imu_wrt_vio);
                        		rc_matrix_times_col_vec_inplace(R_vio_to_local, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, T_vio_ga_wrt_local);
                        
                        		// calculate rotation tag to local
                        		rc_matrix_multiply(R_cam_to_imu_tmp, R_tag_to_cam, R_tag_to_local);
                        		rc_matrix_left_multiply_inplace(correct_R_imu_to_vio, R_tag_to_local);
                        		rc_matrix_left_multiply_inplace(R_vio_to_local, R_tag_to_local);
                        	} 
                        	else if (strcmp(input_pipe, "tracking") == 0)
                        	{
                        
                        		printf("R_cam_to_imu: \n%5.2f %5.2f %5.2f\n %5.2f %5.2f %5.2f\n %5.2f %5.2f %5.2f\n\n",
                        		R_cam_to_imu.d[0][0], R_cam_to_imu.d[0][1], R_cam_to_imu.d[0][2],
                        		R_cam_to_imu.d[1][0], R_cam_to_imu.d[1][1], R_cam_to_imu.d[1][2],
                        		R_cam_to_imu.d[2][0], R_cam_to_imu.d[2][1], R_cam_to_imu.d[2][2]);
                        
                        		// calculate position of tag wrt local
                        		rc_matrix_times_col_vec(R_cam_to_imu, T_tag_wrt_cam, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, T_cam_wrt_imu);
                        		rc_matrix_times_col_vec_inplace(correct_R_imu_to_vio, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, correct_T_imu_wrt_vio);
                        		rc_matrix_times_col_vec_inplace(R_vio_to_local, T_tag_wrt_local);
                        		rc_vector_sum_inplace(T_tag_wrt_local, T_vio_ga_wrt_local);
                        
                        		// calculate rotation tag to local
                        		rc_matrix_multiply(R_cam_to_imu, R_tag_to_cam, R_tag_to_local);
                        		rc_matrix_left_multiply_inplace(correct_R_imu_to_vio, R_tag_to_local);
                        		rc_matrix_left_multiply_inplace(R_vio_to_local, R_tag_to_local);
                        
                        	}
                        
                        	printf("\n__________________________________________________________________________\n");
                        
                        	pthread_mutex_unlock(&tf_mutex);
                        	return 0;
                        }
                        
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