---
title: "Understand system health metrics"
canonical: "https://help.vicon.com/space/ShogunLive121/1253212306/Understand%20system%20health%20metrics"
format: markdown
---
To provide you with a quick way to identify issues with camera calibration, health icons are displayed throughout Shogun Live, and health scores showing centroid connection and image error are displayed in both the System Health Report (see [Understand System Health Report](https://vicon-help.atlassian.net/wiki/spaces/ShogunLive121/pages/1253212273)) and for individual cameras in the Cameras view. Shogun Live also enables you to see when cameras have been knocked and to monitor their temperature.
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## Understand the system health icons
Throughout Shogun Live, the color red is used as a warning of possible issues, the color green is used as an indicator of good system health, while the colors between these extremes (orange, amber, yellow) are used to indicate an interim state.
For example, the color of centroids that are displayed in the **Cameras** view indicates the current state of camera calibration:
- Centroids that are not contributing are displayed in red in the **Cameras** views, indicating that the relevant camera is not well calibrated.
- Centroids from uncalibrated cameras are displayed in gold.
- Centroids from calibrated cameras are green, indicating they are now contributing.
In a **3D View**, the color of the markers shown in the representations of the cameras also indicates whether or not the camera is contributing to the reconstructions. As elsewhere in Shogun, for example in the **System Health Report**, the color red indicates an issue, and helps you to identify a problematic camera.
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On the **System** tab, the camera icons give you an overall indication of the cameras' status.
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| Icon | Meaning |
| --- | --- |
| | Camera is active or connected (and calibrated) |
| | Camera is not calibrated |
| | Camera is (manually) disabled |
| | Camera is connected but not contributing |
| | Camera is disconnected |
| | Camera has been bumped since calibration |
| | General warning symbol indicating an error |
| | Camera was loaded from a previous Shogun session but not yet connected to this instance of Shogun |
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## Use health scores to identify camera calibration issues
You can view the following scores for all cameras and individual cameras in the System Health Report panel (see [Understand System Health Report](https://vicon-help.atlassian.net/wiki/spaces/ShogunLive121/pages/1253212273)), and for individual cameras in the Cameras view.
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### Centroid connection score
The centroid connection score is the percentage of centroids that are connected to labeled object points, calculated over a fixed time window. To be included in the centroid connection score, centroids must be connected to object points. A low centroid score can indicate issues with a particular camera.
> ℹ️ **Note**
> ℹ️ Static centroids that aren't connected to object points (eg, from unused passive markers at the edge of the volume, or from unmasked reflections on a metallic camera truss) are eventually filtered from inclusion in this score by an online masking process. This online masking affects only the centroid connection score and is used to prevent such centroids from affecting the centroid connection score (it would not be clear if the low score indicated centroids from non-object sources, or poor connection of the centroids associated with the object(s) of interest).
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### Image error score
The image error score is the average error for those centroids that are connected to labeled object points. The error here is the distance (in pixels) between a centroid and the projection of the associated labeled object point into the associated camera view.
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The following examples illustrate common calibration issues:
| Example | Calibration issue |
| --- | --- |
|  | **Good/perfect calibration**
This shows a zoomed section of a camera view.
The centroids are displayed as circles with internal crosses to help show the exact centers.
All centroids are connected to labeled object points (indicated by the green lines) and so the Centroid Connection score is high (100%). The centroid centers line up with the projections of the object points in this camera view, and the Image Error score is very low. |
|  | **Noisy calibration **
The estimated calibration for this camera no longer perfectly matches the true calibration. The calibration is close enough that all the centroids can still be connected to the corresponding labeled object point, but the projections of those points are further away from the equivalent centroids.
This results in a high (good) Centroid Connection score, but the Image Error score is higher (worse) than normal, indicating a problem.
This situation might result in some extra noise/jitter in the object's path, particularly as the set of cameras that can see that object change, but in general the object would still be expected to track. |
|  | **Bad calibration (drift) **
The true calibration of the camera has drifted since the initial calibration. Even though the difference is relatively small, it is large enough that that none of the centroids are connected to object point. Unconnected centroids are indicated by being drawn in red.
The Centroid Connection score is very low (0% connected). As there are no connected centroids, it is not possible to compute the Image Error score.
Depending on the number of cameras similarly affected, the tracking may start to show more severe noise/jitter and the object might start to occasionally fail to track in some parts of the volume. |
|  | **Bad calibration (bump/knock)**
The true calibration of the camera significantly differs from the software's stored calibration. This may have been caused by the camera being knocked or deliberated moved since it was last calibrated.
The Centroid Connection score is very low (as in the *Bad Calibration (drift)* example) and again the Image Error score is not computed.
The cameras affected to this extent do not contribute at all to the tracking of objects. This might result in the object failing to track in parts of the volume (depending on the extent of coverage redundancy, primarily the overlap between cameras view frustums). |
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**To display more information about the status of a camera **
1. In the **Workspace**, select the **Cameras** view.
:check_mark: **Tip**: To display the same information as that shown in the following examples, in the **View Filters**, ensure **Camera IDs** and **Always Show Health** are selected.
2. In the **System** panel, select a camera.
3. At the top of the **Cameras** view, hover the mouse pointer over the **Centroid connection score** icon:
Note that, as usual, the color of the icons at the top of the **Cameras** view provides an additional indication of the camera status.
This icon represents the centroid connection score: for the selected camera, the percentage of centroids that are contributing to reconstructions. A low centroid connection score indicates issues with the selected camera.
4. Hover the mouse pointer over the **Image error** icon:
This icon represents the image error: the distance between the 2D image of the markers on the camera and the 3D reconstructions of those markers projected back to the camera sensor.
5. To investigate a camera status further, hover the mouse pointer over any additional camera status icons to the left or right of the other two icons. These additional icons provide further information about the state of the camera: eg, a bumped camera icon and/or a camera temperature warning.
For information about bumped cameras, see [Fix bumped cameras](https://vicon-help.atlassian.net/wiki/spaces/ShogunLive121/pages/1253212445).
If one or more camera's operating temperature is inconsistent with its temperature at calibration, re-calibration is necessary (see [Calibrate cameras](https://vicon-help.atlassian.net/wiki/spaces/ShogunLive121/pages/1253212193)).
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## Observe accelerometer feedback
When a camera's accelerometer measurement exceeds its bump threshold, bump notifications are shown in the System Health Report.
It can be useful to use accelerometer bump notifications to identify problematic cameras and then use the **Recover Camera Pose **operation (see [Fix bumped cameras](https://vicon-help.atlassian.net/wiki/spaces/ShogunLive121/pages/1253212445)) to correct those cameras.
When the bump notifications are required for the process of identifying the problematic camera(s) and then using Recover Camera Pose, it may be useful to enable their display in the System panel and Workspace camera views.
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**To display bump notifications in the System panel and Cameras view:**
1. From the **Settings** menu, select **Preferences**.
2. Go to the **System Health** section and select **Show Bump Notifications Per Camera**.
Bump notifications are now displayed for individual cameras in the **Vicon Cameras** list in the **System** panel.
On Vicon cameras with accelerometers, the status indicators flash blue when the camera is bumped and (on Valkyrie and Vantage cameras only) the display changes to indicate a bumped camera.
In addition to the bump notification warning, the System Health Report also provides a Camera Accelerometer section, which displays a graph showing the maximum accelerometer signal for any camera. This is useful for showing when the cameras accelerometers are detecting motion that may not trigger the bump notification warning but may still be of interest or concern, eg, a door slamming may cause the cameras to momentarily shift but will likely return to their previous position, and the tracking may be affected for a very limited period.
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Monitor camera temperature
Several common issues with camera calibration arise from changes in temperature. Ambient temperature changes may cause thermal expansion/contraction of the camera rig causing camera positions to change from their calibrated values. Internal changes of temperature can lead to internal shifts of lens elements and the sensor that may invalidate calibrated parameters.
For this reason, Vicon cameras, have onboard temperature sensors that can be used to help monitor temperatures. The System Health Report contains a [Camera Temperatures section](https://vicon-help.atlassian.net/wiki/spaces/ShogunLive121/pages/1253212273/Understand+System+Health+Report#CameraTemperaturesSection), which collates all the temperature sensor information for the cameras that can be found in a camera's properties in the System panel (see [Monitor camera temperature (optical cameras only)](https://vicon-help.atlassian.net/wiki/spaces/ShogunLive121/pages/1253212244)).
Generally if there are no observable problems in the tracking of objects and the camera calibration health metrics such as Centroid Connectivity and Image Error do not indicate a problem then changes in temperature can be assumed to be harmless. The temperature warnings are most useful in helping to diagnose issues.