Calibrating a device will enable users to set their location and direction with high accuracy within the vGIS environment. The calibration screen can be accessed in two ways. The first, shows up before entering the AR mode (headset icon) for the first time. The second, can be accessed by selecting the "Recalibrate" option from the main menu.
There are two methods to calibrate a device:
- vGIS Calibration Method
- High-Precision GNSS
vGIS Calibration Method
vGIS calibration method begins in the aerial map view (Fig. 1). Several features become available to aid users in calibrating their device:
Selecting this option will open a menu to the GPS and Bookmark buttons. Selecting GPS will re-center the screen to the current position of the user, and from there allow the user to manually select the area to work with, by scrolling on the screen. Selecting Bookmark will move the aerial map to the bookmark location of the selected team/project. Bookmarks may be pre-set by the company administrator(s) to aid users in calibrating their devices. See Team/Project Selection for more information on bookmarks.
Selecting this button will open up a menu of pre-set layers, with the user being able to select which layers they would like to view. See Managing Layers for more information on layers.
Selecting this button will open up a menu of different map services, with the users being able to select the desired map service.
QR Code Calibration
In the bottom left of the calibration screen, the user can use the QR code calibration method. This method requires planning in advance which points would be used and recording the latitudinal and longitudinal information of each point. The user will then need to print out a QR code for each recorded point from https://vgis.meemim.com/qr-code, position the printout on the position of the point, and then scan each QR code by using this calibration method. If successful, the vGIS system will place a yellow sphere on the scanned QR code. Note, that if you are using a single QR code, you can establish the alignment with help from the "vGIS Calibration".
Calibrating the Device (vGIS Method)
The calibration method requires that the user can identify that their position on the map corresponds to the same position in the real world. The best way to achieve calibration is to start in a position that has identifiable markers in both the aerial map and the real world. Good starting locations include markers like manhole covers, water inlets, telephone poles, road markings, etc.
The white dot in the center of the screen represents the device user, and the blue beam represents the direction that the device user is facing. If the blue dot is not present on the screen, then tap the re-center button. This will re-center the aerial map around the user’s position.
- Upon entering the calibration screen the user will be prompted to “Adjust Your Position” (Fig. 2).
- Perform a pinch-to-zoom gesture on the screen to zoom into the aerial map. This will increase the positioning accuracy. Next, drag a finger across the screen to move the aerial map until the small blue dot on the map corresponds with the device’s location in the real world.
- Once satisfied with the positioning, tap the Next button.
Note: do not change your physical location or move around until you have completed the next step.
Setting your direction (Azimuth/Bearing)
- Once the device's position has been established, the screen will split with the top portion showing a view from the device’s camera, and the bottom portion showing the aerial map (Fig. 2).
- Identify an object that is clearly visible in both the aerial map and the real world. The ideal distance of this objective should be between 50-100 meters (150-300 feet). Objects like straight sections of the curb, manhole covers, telephone poles, road markings, and building corners are all excellent candidates for alignment.
- Drag a finger across the bottom split-screen until the line of sight is aligned with the selected object.
- Once satisfied with the direction, tap the Done button.
Note: the white line pointing straight up from the white dot, and into the split-screen above. This line represents the user’s line of sight.
Aligning Your Direction
- Once the position and direction have been established, the device will prompt the user to “Align With Objects”.
- Move your device camera to align the line of sight in the top split-screen with the selected object in the real world.
- Once satisfied with the alignment, tap the Done button.
- Upon successful completion, both the device’s location and azimuth will be locked in and calibrated. The user may now start navigating in augmented reality.
Once in the augmented reality view, users will have several options to adjust their visuals/position.
- Adjust: Users can adjust their position in the 3D space by pressing the "Adjust" button. In the augmented reality view they will be able to further adjust their elevation, direction, and horizontal placement.
- Layers: Layers allow users to select and deselect the objects they would like to visualize. See Layers
- Menu: The menu allows users to select all sorts of options, including teams/projects, re-calibration, etc. See Main menu.
- Tools: Tools allow users to select various tools that could aid in AR viewing. These include tools like distance trackers, measurement tools, and the most commonly used options.
High-Precision GNSS Calibration Method
If the device is connected to a high-precision GNSS, the location of the device will already be locked in and calibrated. Unlike the vGIS calibration method, the user will not need to adjust their position, but will still need to lock in their direction (azimuth):
- The Walk calibration method begins with a full camera view on the device screen.
- An arrow line will be drawn in front of the user, and they will be prompted to walk on a straight line in the direction of the line (Fig. 3)
- Once the azimuth is locked and calibrated (approximately 10 steps) the user may start navigating augmented reality.
Note: As you move around the job site, make sure the GNSS antenna stays in the same position relative to your phone, tablet or HoloLens.
|Location Accuracy||Directional Accuracy|
|vGIS (high quality aerial maps)||Up to 5 cm/2 in||+/- 0.1°|
|vGIS (low quality aerial maps)||10-20 cm/4-8 in||+/- 0.3°|
|Built-in GPS||30 m/100 ft||+/- 15° *|
|High-precision GNSS devices||Up to 10 cm/4 in; sub-meter in most cases||+/- 1.5°|
|RTK devices||Up to 1 cm||+/- 1.5°|
* Directional accuracy of magnetic compass can be impacted by environmental variables, such as presence of vehicles or other large metal objects.