# Prepare Volume ### Preparing the Setup Area #### Reducing IR Interference In preparation for the calibration process, you will want to prepare your environment by blocking or removing any physical elements that might interfere with your cameras. This includes open windows that might let sunlight in, reflective surfaces throughout the volume, lights which emit IR (incandescent, halogen, high pressure sodium), IR based devices, spare markers, etc. #### Flooring Avoid spaces with reflective or flexible flooring. Reflective flooring can introduce IR interference, and flexible flooring can negatively impact your system's calibration. If either is unavoidable, consider installing mats to reduce reflectivity or dampen movement in the floor. ### Positioning, Cabling and Configuring Hardware #### Planning Camera Placement For 360° camera setups, your goal should be to maximize camera overlap and minimize wasted camera coverage. General tips include the following: * Mount cameras at the desired maximum height of the capture volume, and aim them so they look straight across the top of the volume. * For cameras with rectangular FOVs, mount so the imager is in landscape mode. (Note that in some OptiTrack cameras, the orientation of the imager and the case are opposite each other.) In very small setup areas, cameras can be aimed in portrait to increase vertical coverage, but this typically reduces camera overlap, which can reduce marker continuity and data quality. * Distribute the cameras equidistantly around the setup area. * Aim corner and side cameras straight ahead and cameras adjacent to the corner down the baseline of the volume gutter. #### Cabling When placing cameras, keep cable length restrictions in mind. Ethernet cables can extend up to 100m from camera to switch. USB cameras must have no more than 5m of cable and no extensions between the camera and hub. The hub must be connected directly to the computer with no more than one 5m USB cable and up to two 5m *active* USB extensions for a total of 15m between the computer and the hub. #### USB Load Balancing When connecting hubs to the computer, load balancing becomes important. Most computers have several USB ports on the front and back, all of which go through two USB controllers. It is recommended (especially in larger camera count systems) that you evenly split the cameras between the USB controllers to best make use of the available bandwidth. #### Network setup OptiTrack Ethernet cameras connect to the computer through a Gigabit (1000 Mb/second) Ethernet port. Camera network traffic should be segmented from the office or other local area networks to avoid interference and congestion. If the computer used for capture is connected to an existing network, then a second Ethernet port or add-on network card can be used for connecting the computer to the camera network. For best performance, do not connect devices other than the capture computer to the camera network. Add-on network cards should be installed if additional network ports are required. *Note: if your Ethernet cameras have trouble connecting to the system, you might need to turn off your computer's firewall.* ### Calibrating Your System #### Camera Masking Once the environment has been prepped, you can easily mask out any remaining light sources—like IR interference from the other cameras in the volume—using one of several camera masking tools: The simplest option is to use Motive’s one-click auto-masking feature. It will instantly mask bright spots in all cameras, simultaneously. You can also clear all masking with a single click. If you need to manually mask some portions of a camera, Motive has tools for drawing a circle mask, drawing a square mask, or using the pencil tool for drawing and erasing single pixels. Note that you can also use the "block visible" button on the calibration pane to mask all bright spots, simultaneously. #### Wanding Once 2D camera masking is complete, begin the calibration process by clicking the "start wanding" button. The calibration engine will begin recording samples as soon as the calibration wand is detected. The calibration engine pane will turn green once a sufficient number of samples have been collected. However, while capturing a sufficient sample count is important, the primary goal during wanding is to maximize coverage, both in the 2D camera views and throughout the desired physical capture volume. You should not stop wanding until sufficient coverage has been achieved. To thoroughly cover the physical volume, walk a grid pattern throughout the space—covering every area that you desire to capture, from the floor to the top of the volume. You will know when you have sufficient camera coverage when each 2D camera view is thoroughly covered edge-to-edge with well-distributed wanding samples. #### Calculation After completely wanding the capture volume, and once the 2D camera views have sufficient coverage, you can move on to calculation. After beginning calculation, simply wait for the calibration to converge on a solution. To generate the most accurate calibration possible, you can allow the engine to continue to calculate for as long as you deem necessary. However, the time to achieve an exceptional calibration will usually only run a couple of minutes. During calculation, you can monitor progress in 3D by opening the 3D volume view, which will contain a cloud of wand samples. Initially, the samples will be red, which indicates higher sample error. The samples will begin turning blue as the quality improves. A completely blue sample cloud indicates that the calculation is nearing completion. Confirm the progress of the calculation by referring back to the calibration engine pane, which should show that individual camera qualities are all excellent or exceptional, along with a notification that the calibration is ready to apply. #### Applying the Results After the results are applied, you will be prompted to save a recording of the wanding. After saving the wanding, the ground plane can be set, which will complete the calibration process and prompt you to save the calibration file. #### Verifying the Results Run the Volume Accuracy Tool to verify the quality of the calibration. This tool measures the deviation between the *measured* and *actual* lengths of the calibration wand. Run this tool any time that a measurement of volume accuracy is required. ### See Also For more information on preparing the volume, visit the Calibration, Cameras Pane, Devices Pane, and Application Settings glossary entries.