Sensoray 2251 Rev.A - Manual (Page 36)

The second threshold is the motion vector threshold. The recommended range is 0-1600. For
testing purposes(with sensitivity = 80), start at MV=700. The MV threshold will detect slow
motion across the target better than SAD.
Finally, there is a sensitivity value. It may be set from 0-100. A recommended start setting is 80.
In general, higher thresholds may be used for higher sensitivity settings.
Mathematically, motion detection in the chip is calculated as follows:
H/w comes up with a set of MV for each MB in each direction, MV = ((Vx * Vx) + Vy*Vy))
>> 2).
If ((Vx*Vx+Vy*Vy)>>2)>MV_THRESHOLD), then this MB is motion detected.
If (Sad>SAD_THRESHOLD), then this MB is also motion detected.
If the detected MB is in a specified region, a motion map is produced and a notification
sent to the user.
The motion detection configuration structure is as follows (mid2250types.h) (The last region is
reserved):
typedef struct
{
MID2250_PointCorrds_t ULPoint[ 4 ];
MID2250_PointCorrds_t BRPoint[ 4 ];
unsigned short u32SADThresholdValues[ 4 ];
unsigned short u32MVThresholdValues[ 4 ];
unsigned short u32SensitivityValues[ 4 ];
} MID2250_MDConfig_t;
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