Improve interpolation of OBD gauges in video overlay?

Request and discussion on new / to change features
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schluerfi1978
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Improve interpolation of OBD gauges in video overlay?

Post by schluerfi1978 »

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
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Harry
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Re: Improve interpolation of OBD gauges in video overlay?

Post by Harry »

Please export one lap to .hlptrl and send it to me. Please add a link to this thread. I can't promise a time line currently as I have lots to do with iOS and unsolved issues, but I will keep it in my list.

Harry
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schluerfi1978
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Re: Improve interpolation of OBD gauges in video overlay?

Post by schluerfi1978 »

OK, I just sent you an e-mail with the data and a link to an example video!
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Harry
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Re: Improve interpolation of OBD gauges in video overlay?

Post by Harry »

The data is enough, I need to check the pattern.
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scociu
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Re: Improve interpolation of OBD gauges in video overlay?

Post by scociu »

Reviving this thread as i don't think it's worth creating a new one.

I seem to run into an issue where the obd data is not interpolated at all in the overlay. The update rate seems to be at a steady 2hz when checking with real-time analysis. Next thing i think will try disabling all PIDs except for the rpm one, to see if it improves the situation.
BT1
XGPS160
iphone 5s
Alfa 156 GTA 2003 (OBD2 no can)

Video: https://www.youtube.com/watch?v=qIH5MKCi1Pc
I can export the lap data as well or do a trace session, just let me know.
BT1 - XGPS160 - iphone 5s - Alfa 156 GTA 2003 (OBD2 no can)
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Harry
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Re: Improve interpolation of OBD gauges in video overlay?

Post by Harry »

Please let us know about the LapTimer version you had recorded the lap overlaid with. Furthermore, which OBD update rate do you get displayed typically (see Sensor List or Engine View).

- Harry
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scociu
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Re: Improve interpolation of OBD gauges in video overlay?

Post by scociu »

LapTimer GranPrix 20.0.17
I think the OBD update rate is the one for the full set if PIDs as the other one was higher than 2hz, close to 8hz if i recall correctly.
BT1 - XGPS160 - iphone 5s - Alfa 156 GTA 2003 (OBD2 no can)
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Harry
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Re: Improve interpolation of OBD gauges in video overlay?

Post by Harry »

Please export the lap overlaid to .hlptrl and send it to me (Harry@gps-laptimer.de). Please include a note "Improve interpolation of OBD gauges in video overlay?" so I get the context.

- Harry
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scociu
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Re: Improve interpolation of OBD gauges in video overlay?

Post by scociu »

Lap export sent.

Attaching here two photos of the OBD sensor information, before(as in the lap in question) and after PID exclusion. Didn't get to test if there is any improvement in the overlay interpolation after doing the exclusion.
obd-sensor.jpg
obd-sensor.jpg (57.19 KiB) Viewed 1991 times
BT1 - XGPS160 - iphone 5s - Alfa 156 GTA 2003 (OBD2 no can)
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Re: Improve interpolation of OBD gauges in video overlay?

Post by Harry »

You will not see a change. The problem is an optimization added for high update rate OBD / GPS configurations added to v20.0.17. It seems introduces steps for low update rate OBDs :-(

LapTimer v20.0.18 will come with a fix.

Harry
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