Measuring Speed by Video

[rcs2022]

Currently my eagletree is out, so I don't have any means to measure the speed of my savage except by taping my phone on it and using the phone GPS, which not that good of an idea, and accuracy dunno how accurate the phone will be. The speed radar gun i surmise is the most accurate way, second comes an accurate GPS, I was relying on my GPS module hooked up to my eagletree, should be quite accurate but had no means to verify.

Anyway, without any of the above available, thought of using a video camera to do so, here's how:

Placed the camera close to ground to be at the level of the savage, tried to do the runs perpendicular to the FOV of the camera, after recording the video, did some screen captures of successive frames as such:
















Combine alltogether in a photo editing software, merging the layers in one layer as so:



Use the ruler option and set vertical guides in the center of the wheels for some frames:





Knowing the length of the wheel base of my truck is 39.5cm, and the video is 30 frames per second, can calculate the total length traveled in the 5/30 seconds, and after some calculations....... i get 83 km/hr, should be accurate enough, the run was quite perpendicular to the cam.

Note my truck with the 1717 and XL2 is geared for 104.6 km/hr @3.7V

I'd like to test this theory versus my eagletree gps when i get it back working. Thought of sharing it in the meantime.