Video Quality/Hardware Advice

[Yosemite]

I am not a video professional, not even an amateur. Over the last several years I have been asked by my heavy construction industry related clients to provide them with pre- and post-construction videos of roadway surfaces that they use to reach their work sites during their heavy construction projects; note that my clients are not roadway construction contractors, rather they travel across the roadways with semi-trucks to deliver heavy equipment to various locations along large linear projects sometimes spanning up to 100 miles. The purpose of the videos is to record the quality conditions of the roadway surfaces before and after construction so that they can document damages to the roadway surfaces that may have been present before their work began and to confirm damages that they may have actually caused and are responsible for repairing. I should note that the primary roadways of concern are secondary roads not interstates or state highways as these are built to significantly higher strengths, but the secondary roadways are often relatively thin layers of asphalt that can be damaged more easily. I have done this previously by attaching a GoPro to the hood of a vehicle and driving the roads that they use over the course of construction; note that this may include many miles of roads (up to 100 miles) and may take up to six months to complete. While the videos that I have provided have been mostly acceptable, I am looking for advice on how to improve the quality of the video images such that fine details in the roadway surfaces can be viewed better (cracks in roads can be hard to see at 25 mph). I have noticed that pausing a video or trying to manually slow it down often only results in blurry images. So my questions are, how can I produce very high quality videos that can provide very clear images capable of displaying fine cracks (e.g. 1/4" spider cracks, etc.) in the moving video but also when video is paused to study the crack, pothole, etc.; are there recommendations for higher quality cameras (recall I was using a GoPro), better formats, better framerates, etc. I should note that my typical video delivery method is to save the videos to an external hard drive(s) and turn the hard drive over to them for their use. Thank you in advance for any advice you can provide.

[dellsam34]

The solution to your problem if frame rate, If you want to pause a video with no motion blur you need the highest frame rate possible without affecting the overall brightness level of the scene, the key to keeping the brightness level within a reasonable level is the light conditions, Make sure you shoot in a well lit conditions such as a sunny day and use the highest possible frame rate. I don't have recommendations for hardware and frame rates but hope other members who are familiar with shooting sports can chime in and recommend the right gear for you.

[Bwaak]

For a sharp frame grab you need high shutter speed. 25 MPH is about 36 ft/s or 432 in/s. With shutter speed of 1/500 s you will get about 1 inch smear in a frame. You can go from here. IDK whether GoPro allows to manually set shutter speed or to select shutter speed priority mode. Remember to do it in bright light, otherwise the image will be dim or noisy.

[dellsam34]

Yes, Shutter speed, I was looking for that technical word and used frame rate instead which is technically wrong because you could shoot 30p only but with higher shutter speed. With a very bright sunny day he could go lower than 1/500, maybe 1/2000 or less with the right lens and filters and may need a SLR video camera with more sensitive imaging sensor, not sure if the go pro is up to that.

[Cornucopia]

Shutter speed and FrameRate are inter-related. In video, one cannot ever have a slower shutter speed than the framerate, and usually the shutter speed is 1/2 the duration of the framerate (180 degree shutter angle), so 25FPS = shutter speed of 1/25sec when using 360degree angle (full open throughout frame duration) or 1/50sec when using 180degree angle (1/2 duration), or 1/100sec when using 90degree angle). Of course, shorter shutter speed duration means less exposure = darker image, so you must somehow compensate for proper exposure (more light, more open iris, higher gain/sensitivity).

Capture of freeze motion is based on speed, but it is also (actually more accurately) based on the DISTANCE. And that distance in the frame is based on both the distance away from the lens and which direction the motion is heading (less noticeable if heading toward/away, more noticeable if heading across frame). a 25MPH motion looks a LOT more drastic at 10 feet away than at 50 feet away or 200 feet away. There are calcs that can figure out exactly what you need to set your equipment to based on all these factors.


Scott

[dellsam34]

Some use drone shooting at low altitude, It is probably the best option for your purpose, Not good enough if you want to count the number of gravels on the road but good enough for showing the road condition and at that altitude you wouldn't have too much of motion blur.