The images associated with SharpZ3 reads and hits are stored on disk in G64 files by an Archiver. You can estimate the disk space required to store these images if you know the average number of reads and hits processed by the ALPR Manager per day.
For every license plate read or hit processed by the ALPR Manager, the Archiver stores a set
of four images:
- One context camera image (in either high resolution or low resolution)
- One ALPR camera image (cropped to show only the license plate)
- One context camera thumbnail image
- One ALPR camera thumbnail image
The size of the image set depends on the model of the Sharp camera and whether the context camera is configured to take images in high resolution or low resolution.
Use the following formula to estimate the disk space you need for the desired image retention
periods.
Disk space = (ReadsPD x ImageSize x ReadIRP) + (HitsPD x ImageSize x HitIRP)where:
- ReadsPD
- Average number of reads per day.
- ImageSize
- Estimated image size per read (depends on the Sharp model and configuration).
- ReadIRP
- Read image retention period (see ALPR Manager's Properties tab).
- HitsPD
- Average number of hits per day.
- HitIRP
- Hit image retention period (see ALPR Manager's Properties tab).
If your patrol vehicles are equipped with wheel imaging cameras, double the number of hits per day in your formula (there is typically one wheel image per hit).
The following table gives you the rough estimates of the image size per read based on the Sharp model and configuration.
| Type of image | SharpZ3 image size |
|---|---|
| High-resolution configuration | |
| Context camera image | ~160 KB |
| ALPR camera image (cropped) | ~2 KB |
| Context camera thumbnail image | ~2 KB |
| ALPR camera thumbnail image | ~1 KB |
| Total image size per read: | ~165 KB |
| Low-resolution configuration | |
| Context camera image | - |
| ALPR camera image (cropped) | - |
| Context camera thumbnail image | - |
| ALPR camera thumbnail image | - |
| Total image size per read: | - |
NOTE:
- If a read or hit is protected and must be kept beyond its specified retention period, it requires more disk space for its associated images than what is calculated for a single event. Because the Archiver stores multiple ALPR images in a single G64 file, if one image in the file is protected, then all other images in the file are also protected. This uses up more disk space over time. However, an image whose corresponding read or hit has been deleted can no longer be read because the G64 files are encrypted.
- If the Archiver is assigned to more than one ALPR Manager, add the numbers for all ALPR Manager roles together.