MD cars going past my house - Creative Uses of CHDK - CHDK Forum

MD cars going past my house

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MD cars going past my house
« on: 11 / May / 2009, 20:39:30 »
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I'm sure someone else has done this but I decided to do it myself

http://www.youtube.com/watch?v=-iEQqmknzs8#

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Offline @rt

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Re: MD cars going past my house
« Reply #1 on: 25 / June / 2009, 02:46:03 »
Interesting... If the feature is supposed to be fast enough to capture lightning,
why are the cars all in different places?
Shouldn't they be captured as soon as they enter the frame?

Maybe I'm missing something.. I'm a freakin one post newbie :D
If not actually, then potentially.

Re: MD cars going past my house
« Reply #2 on: 25 / June / 2009, 10:09:22 »
Much depends on how many detection cells they have enabled (rows and columns), the sensitivity threshold to detect that motion, and how much motion is occurring during shooting. If one car has already triggered a shoot event, then the camera has to cycle and prepare itself for the next MD and shoot event. The time it takes to save a file and reset to detect motion. If there is already activity in the FOV after it comes out of its save-file and reset cycle then it will shoot immediately again after it is done saving the previous image. If there is no motion then it waits to detect some.

If you look at these frames you'll see a recurring theme going on. Either a car has just entered from either side, or there's one in the middle with another one at either edge. I suspect the one in the middle triggered one event from a previous frame, then the one at the edge triggered another event as the first one reached the middle. There are the few where there is a car alone in the center. This is most likely due to the camera already being busy saving and resetting, when ready the one already moving in the middle of the FOV will trigger the camera again. (edit) Notice too the wildly swinging trees and branches, and the abrupt changes from sunlight to clouds. All of these can trigger motion detection depending on how you set the sensitivity levels in the script parameters.

Some of the added benefits of the MD system is that you can set which rows and columns you want to use for detection and mask out all others. Had the originator of this sequence set the MD script parameters so only one small detection cell in the middle of his viewfinder was active, then only cars in the very center would have triggered an image, instead of what is occurring, any motion anywhere is triggering a shot.

Had they also used their camera's "Color Accent" mode if it has it, and only had it display red colors, all else being B&W, then they could also have set the script's "Measure Mode" (Y,U,V,R,G,B) to a value of 3. That causing it to detect only changes on the Red channel. Then only red cars in the middle would have triggered a shot. If you have RAW or DNG saving enabled then those files are unaffected by the "Color Accent" effect that is only applied to the JPG files.

« Last Edit: 25 / June / 2009, 10:38:55 by NewbieToobie »

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Offline @rt

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Re: MD cars going past my house
« Reply #3 on: 25 / June / 2009, 17:34:30 »
Ok, Thanks for clearing it up.
I since had a play with a motion detect script and understand :)
If not actually, then potentially.


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Offline don

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Re: MD cars going past my house
« Reply #4 on: 30 / June / 2009, 13:05:34 »
hi, I did a video very much like yours.
 I set my canon a610 into my mailbox with a chdk MD script,I can't remember exactly which one.
I did have the mask on and adjusted so that only motion in the very center caused activation.

[url=http://www-us.flickr.com/photos/88476838@N00/3430095918/]http://www-us.flickr.com/photos/88476838@N00/3430095918/
[/url]
I discarded all the pictures going in the opposite direction,
I discarded about 10% of the rest for being of large trucks or being to far left or right.
Considering that the cars were going anywhere from 45mph to 80? mph, I thought it did a great job.
I would post the video here but I never could figure out how to do that,,lol
« Last Edit: 30 / June / 2009, 13:26:05 by don »

 

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