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For accurate license plate readings, plate characters in the field of view should appear between 30 and 45 pixels high. Estimate positioning based on the camera’s resolution using the following chart:
| Resolution | Megapixels | Approximate Max Car Widths* | Maximum Width |
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| Analog | 0.3 | 1.0 | 5' (1.5 m) |
| 1024 x 768 | 0.7 | 1.4 | 7’ (2.1 m) |
| 1280 x 1024 | 1.3 | 1.8 | 9’ (2.7 m) |
| 1600 x 1200 | 2.0 | 2.2 | 11’ (3.3 m) |
| 2048 x 1536 | 3.0 | 2.9 | 14.5’ (4.4 m) |
Mounting
Choose to offset the camera either vertically or horizontally, and use the tables below to judge how far from the recording point a camera may be mounted:
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Sample Vertical Mounting Values
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| Horizontal Distance to Car (D): | 10’ (3 m) | 12’ (3.7 m) | 16’ (4.9 m) | 20’ (6.1 m) | 30’ (9.1 m) | 40’ (12.2 m) | 50’ (15.2 m) |
| Max Mounting Height (H) | 7’ (2.1 m) | 8’ (2.4 m) | 10’ (3 m) | 12’ (3.7 m) | 17’ (5.2 m) | 22’ (6.7 m) | 27’ (8.2 m) |
- Horizontal — Mount the camera at the same height as the license plates. The formula for calculating max mounting side deflection (M) based on distance to the car (D) is D/2 = M
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Sample Horizontal Mounting Values
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| Horizontal Distance to Car (D): | 10’ (3 m) | 12’ (3.7 m) | 16’ (4.9 m) | 20’ (6.1 m) |
| Max Mounting Side Deflection (M): | 5’ (1.5 m) | 6’ (1.8 m) | 8’ (2.4 m) | 10’ (3 m) |
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Diagonal mounting (positioning the camera both above and to the side of the recording point) is not recommended. |
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After you have obtained the license key, enter it in the License Settings dialog in System Manager:
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- In the Configure panel of System Manager, select the appliance name. The system settings will appear to the right.
- Click Common Operations, then click License Settings.
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3. In the License Settings dialog, click Add/Update License Key.
4. Type the license key in the pop-up box.
5. Click the Add/Update License Key button.
6. The License Settings window will update to reflect that a license key was applied.
7. Click Close to return to the Configure panel. |
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Install LPR Plug-In
Installing LPR Plug-in Package
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- Launch 3VR System Manager.
- In the Configure panel, click the plus sign beside the appliance name.
- Right-click the Plug-ins folder and select Add Plug-in.
- In the resulting Confirm dialog box, click Install to proceed.
- Navigate to the folder containing the plug-in file (Plugin-LPR-1.0.1.1547-en-us.3pg ) and click to highlight the file.
- Click OK. The plug-in will now begin installing.
- When the plug-in is installed, it will appear below Plug-ins in System Manager.
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Binding Cameras to Plug-in
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- Click the plug-in name to view its settings.
- On the right side of System Manager, select the Bound Cameras field and click the ... button.
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3. In the Bind Plug-in to Cameras dialog box, click the check box beside each camera that should be configured to capture license plates. 4. Click OK to return to the Configure panel. |  Image Modified
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Configuring Global Plug-In Settings
The first step in plug-in configuration is to edit the global settings. To access this dialog:
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- In the Configure panel, select the plug-in name to view its settings.
- Click Edit Settings.
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Select Plate Region
In the Edit Global Settings dialog, open the Plate Region drop-down menu and select the appropriate value:
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If a value other than US_Standard was selected for the Plate Region (step 4.1), you will need to enter a valid license key for premium LPR before proceeding with configuration:
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- Copy (select the text and press Ctrl+C) the 32-character code from the Licensing Question field in the Edit Global Settings dialog.
- Paste (press Ctrl+V) the licensing question into an email to 3VR Technical Support (support@3VR.com).
In your email, you must include the system serial number and the number of cameras of PLPR purchased (reference the PO
number of the order if available). Please also provide your contact information and the customer/reseller company name. - 3VR Technical Support will respond with the matching 30-character key within 1 business day.
- Copy (CTRL-C) and paste (CTRL-V) the key from the email into the Licensing Answer field in System Manager.
Click OK to save and return to the Configure panel. | Note |
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The Licensing Status field will display “Invalid” until the 3VR system software is restarted. |
In the Configure panel, right-click the appliance name and
select Restart 3VR Software.
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7. In the pop-up box that appears, click Restart to proceed.
Wait 1-2 minutes for the software to restart. When the restart is complete, verify that the plug-in was correctly licensed: 8. Sign in to System Manager.
9. Under Plug-ins, select the LPR plug-in.
10. Click Edit Settings.
11. Check the Licensing Status field. If the number of cameras bound to the plug-in is less than or equal to the number of licensed
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12. If more cameras are bound than are licensed or there is another problem with the Licensing Answer, the Licensing Status
field will display “invalid”. | Note |
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If more cameras are bound to the plug-in than are licensed for
Premium LPR, the plug-in will ignore any cameras in excess of
the number of LPR cameras purchased. |
13. If necessary, unbind cameras and restart the 3VR software, then re-check the Licensing Status. |
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Configuring Per-Camera Plug-In Settings
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- After binding the plug-in to cameras (step 3.2), links to edit camera-specific settings will appear under Bound Cameras for each camera.
- Click a link (for example Edit “17. Garage West”) to edit the settings for that camera.
The following settings must be configured for each camera
bound to the LPR plug-in: |  Image Modified
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Setting Text Size
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In the Text Size tab of the Edit Settings dialog, resize the orange
box until it is approximately the height of license plate characters in the underlying video feed. | Note |
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This is especially important for license plates with wide borders. The positioning of the box in the video player is irrelevant. |
This is especially important for license plates with wide borders.
The positioning of the box in the video player is irrelevant.
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For best results, wait until a car enters the field of view,
then click the pause button ( Image Modified) to freeze the video on the current frame. |
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Setting Plate Angle
In the Plate Angle tab of the Edit Settings dialog, click and drag the end points of the line so that it is represents the tilt of a typical license plate as it appears in the camera view. This setting help the LPR algorithm compensate for a camera that is positioned slightly to the left or right of the capture point.
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Cameras with a wide field of view encompassing two or more traffic streams must have lanes configured in the field of view. Lanes are configured in the Lanes tab of the Edit Settings dialog.
To draw a new lane:
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- Click the polygon icon (located below the video player).
- Click the video player to begin drawing a lane. Each click of
the mouse will create a new line segment. To complete the
polygon, click the mouse at your start position (the initial
vertex).
The width of the lane should be approximately the width of
the back of a car as it appears in the camera view. - When the lane has been created, edit the Name of the lane
and make sure that the check box in the Enabled column is
checked. - Repeat for any remaining lanes appearing in the field of view.
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- The name of the lane will appear on license plate events captured by the camera.
- Lanes may optionally be configured for cameras with only one lane appearing in the field of view, but they are required
for multi-lane cameras. - Once a lane (or multiple lanes) has been defined for a camera, any part of the field of view outside of the lanes will not
be analyzed for plates. Consequently, lanes can be used to define an exclusion zone for the LPR analytic. However, if
lanes are configured and then disabled, no plates will be captured - the analytic will not return to scanning the full frame
until the lanes are deleted. - Lanes should be drawn slightly larger than the width of a typical car as it appears in the camera view.
- Only megapixel cameras should be configured with multiple lanes.
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Finalizing Configuration
Restart System Software
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- In the Configure panel, right-click the appliance name and select Restart 3VR Software.
- In the pop-up box that appears, click Restart to proceed. Wait 1-2 minutes for the software to restart.
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Verify Successful Configuration
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Text Size: Size Tolerance
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| This setting controls the amount that the text on a license plate can vary in size from the size specified by the orange Text Size box. |  Image Modified
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| Increasing this value will result in more false positives and also increase the CPU load required for the analytic. Decreasing it will result in fewer license plate matches (as some plates may be rejected due to their out-of-bounds height). |  Image Modified
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Parameters: Minimum Track Time for an Event
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