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First tests with background patterns generated on a screen

A project log for Schlieren-Videography

With this project I want to show you how you can make Schlieren-Videography at home. To do so we will use the Moiré-effect.

Mark Dammer MM0DQMMark Dammer MM0DQM 08/08/2016 at 15:564 Comments

These tests use background patterns on a screen instead of a printed moire. The idea is to be able to project the pattern on a screen or wall for larger scale schlieren videography.

Test setup with stripe pattern on screen and Logitech c930e camera

On top the test setup with a stripe pattern on the external screen an a Logitech c930e camera.

In the first video a stripe pattern similar to the printed moire patterns is used:

This video is an attempt to get a better image by using a chequerboard pattern:

Discussions

Jarrett wrote 08/08/2016 at 17:00 point

What are the chances that this could work with real world backgrounds?

I know that moving scenery would ruin the effect, but I wonder if there's some way of processing it, still. Perhaps with two camera to identify and filter out the background somehow.

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Mark Dammer MM0DQM wrote 08/08/2016 at 18:14 point

Real world backgrounds can work if they offer enough contrast. It's definitely worth experimenting! The main problem is that the signal - the very small changes in light intensity caused by the schlieren effect - is very small compared to the "noise" in the form of movement etc.

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Jarrett wrote 08/08/2016 at 18:26 point

Part of the reason I ask is because that technique would be pretty fantastic for paragliding. Finding thermals is difficult, mostly done with educated guesses and following birds, but a thermal air camera? Amazing.

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Jan--Henrik wrote 08/08/2016 at 18:56 point

Earlier I tried a version, which could work outside, as reference-image I used the last one taken, it was not that great, but worked. I think that can work.

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