General > General high-speed discussion
Measuring Speed
thebishop:
--- Quote from: wilheldp on September 19, 2017, 03:07:21 PM ---
--- Quote from: thebishop on September 19, 2017, 01:48:13 PM ---https://www.amazon.com/Stripe-Black-White-Fabric-Yard/dp/B00QFHHK32/ref=pd_sbs_201_3?_encoding=UTF8&psc=1&refRID=80BQSVXYM05QWKWJXACC ?
:)
--- End quote ---
That might be crazy enough to work. I could cut off some of the black strips and make 1-foot segments to put below the 1-inch segments. I wonder how accurate their 1" strips are...not that any of this is going to be super-precise anyway.
--- End quote ---
The important thing is that the striping is uniform, then you can simply adjust by measuring the exact width.
NoDak:
--- Quote from: thebishop on September 20, 2017, 12:12:09 AM ---
--- Quote from: wilheldp on September 19, 2017, 03:07:21 PM ---
--- Quote from: thebishop on September 19, 2017, 01:48:13 PM ---https://www.amazon.com/Stripe-Black-White-Fabric-Yard/dp/B00QFHHK32/ref=pd_sbs_201_3?_encoding=UTF8&psc=1&refRID=80BQSVXYM05QWKWJXACC ?
:)
--- End quote ---
That might be crazy enough to work. I could cut off some of the black strips and make 1-foot segments to put below the 1-inch segments. I wonder how accurate their 1" strips are...not that any of this is going to be super-precise anyway.
--- End quote ---
The important thing is that the striping is uniform, then you can simply adjust by measuring the exact width.
--- End quote ---
True, that is the big thing. One would need to have some in front of them and measure with a calipers to find the actual width.
pstest:
cheap and dirty way to make a checkered fiducial backdrop is in MS Excel - Choose the cell size desired. Blacken cell A1 and then every other cell in that column go to column B and blacken cell B2 and then every other cell int hat column - repeat until you have a grid - size the grid for your application and print as many copies required to complete your backdrop - glue the printed grids to a piece of cardboard required for your backdrop - measure distance of camera lens to backdrop.
gyppor:
If you need something long a telescoping staff for a laser level could work, can be had relatively cheap and off the shelf from a survey place. The only issue I can see is they're not very wide.
http://www.ebay.ca/itm/2-pcs-of-CST-4M-Metric-Telescoping-Aluminum-Rod-Metric-E-06-804MM-with-Bag-/142216661926?hash=item211cc60ba6:g:-pQAAOSw241YVvGl
AimedResearch:
You might be looking for a quilter's ruler or cutting mat. They are sold clear (for your own background) or white among other colors.
Honestly, if a TV show is using a grid (behind or outside the plane of travel) it is only for show. If you are interested in accuracy, you use an image calibration in the plane of travel. This means you have a second image file for your calibration grid in the plane of travel and reference it for your tests. You update the calibration every time you move the camera or adjust the lens. If you only have video editing software, then you make the calibration image transparent and overlay it to your test videos. If you have decent motion analysis software, then you can have on-screen point tracking.
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