Improve interpolation of OBD gauges in video overlay?
Posted: Thu Sep 25, 2014 11:58 am
Hi Harry,
I'm using an external 5 Hz GPS tracker and my car delivers unfortunately only 1 Hz OBD data (not a too old-fashioned car - a 2009 BMW Z4 Coupé ... however, no CAN Bus yet).
I assume that HLT is aligning all data according to the GPS data interval.For the lap data files, this means that the time interval between the lines is 0.2 sec and every line is updated with new GPS positional data. For OBD data (rpm, throttle, ...), however, there are always blocks of 5 lines (= 1 sec) with the same data value due to the low 1 Hz frequency.
When I now do a video overlay with this data, the rpm and throttle display is very jerky because all gauges are obviously updated every 0.2 sec with some interpolation for the change in the gauge.
Due to the above-mentioned 5 line blocks, the OBD values stay the same for 0.8 sec, and in the remaining 0.2 sec, HLT creates the gauge movement towards the next value (again present as a 5 line block) by interpolation and thus creates the jerkiness of the display (0.8 sec stop - 0.2 sec move - 0.8 sec stop - 0.2 sec move ...).
When I use 1 Hz GPS along with the 1 Hz OBD, the gauges were moving smoothly because there was nothing similar in the data to the 5 line blocks in the OBD data, as it was updated at the same rate as the GPS data.
Is there a chance that you will modify the video overlay that the individual update rates for different gauges are used for the interpolation of the gauges so that they run more smoothly on low-frequency OBD cars? This would be a great improvement in video overlay appearence for everybody running HLT with a low-frequency OBD car in combination with a high-frequency GPS.
BR,
Michael
I'm using an external 5 Hz GPS tracker and my car delivers unfortunately only 1 Hz OBD data (not a too old-fashioned car - a 2009 BMW Z4 Coupé ... however, no CAN Bus yet).
I assume that HLT is aligning all data according to the GPS data interval.For the lap data files, this means that the time interval between the lines is 0.2 sec and every line is updated with new GPS positional data. For OBD data (rpm, throttle, ...), however, there are always blocks of 5 lines (= 1 sec) with the same data value due to the low 1 Hz frequency.
When I now do a video overlay with this data, the rpm and throttle display is very jerky because all gauges are obviously updated every 0.2 sec with some interpolation for the change in the gauge.
Due to the above-mentioned 5 line blocks, the OBD values stay the same for 0.8 sec, and in the remaining 0.2 sec, HLT creates the gauge movement towards the next value (again present as a 5 line block) by interpolation and thus creates the jerkiness of the display (0.8 sec stop - 0.2 sec move - 0.8 sec stop - 0.2 sec move ...).
When I use 1 Hz GPS along with the 1 Hz OBD, the gauges were moving smoothly because there was nothing similar in the data to the 5 line blocks in the OBD data, as it was updated at the same rate as the GPS data.
Is there a chance that you will modify the video overlay that the individual update rates for different gauges are used for the interpolation of the gauges so that they run more smoothly on low-frequency OBD cars? This would be a great improvement in video overlay appearence for everybody running HLT with a low-frequency OBD car in combination with a high-frequency GPS.
BR,
Michael