Inverse motion detection

sbryan01

2

« on: 29 / December / 2008, 15:54:23 »

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I just got a new A590IS, and have a specific use that I want to try with the camera. I have not yet tried any CHDK features or scripts on it.

I know that there are motion detection implementations that will fire the shutter if enough change occurs between frames. What I have in mind is kind of similar but was wondering if it is already supported / easy / possible. What I want to be able to do is to shoot a photo from exactly the same location and perspective at some later date, without using a tripod or physical landmarks.

The idea is to flicker the old image with the current display back and forth so that I can establish when I am in the same position as I originally was when the first photo was taken. In essence, this is kind of an inverse motion detection because I want to take the photo manually after I have minimized the changes in perspective / position using feedback from the display. Good enhancements wouild be to also automatically set the zoom to the position used in the first photo before the second one is taken.

Is this possible / hard / easy?

Thanks in advance for all replies.

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fudgey

1705
a570is

Re: Inverse motion detection

« Reply #1 on: 29 / December / 2008, 16:44:30 »

The motion detector is not usable for this (but I did write an AntiMD script months ago, it's in the scripts forum), but you can use edge overlay for this exact purpose by saving an overlay and then loading it later.

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sbryan01

2

Re: Inverse motion detection

« Reply #2 on: 29 / December / 2008, 17:23:58 »

Fudgey,

Thanks for the pointers. Yes, the edge overlay sounds exactly like what I am looking for, provided that you can overlay the saved edges with the current "live" image and manually shoot when the edges are aligned. Ideally, the first photo and its overlay should be saved (because the before and after photos are of interest). Is this overlay capability easily accessed from a script? Do I need to download any particular build to get this feature? I have looked briefly at the scripting language and it is not obvious to me how special commands from specific builds with special capabilities are accessed.

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fudgey

1705
a570is

Re: Inverse motion detection

« Reply #3 on: 30 / December / 2008, 14:02:46 »

There are no scripts involved with edge overlay. It's for interactive shooting. Look for it in the CHDK menu.

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