Has anyone ever tried to capture the laser pointer from a camera facing a projection screen … and then overlayed just that point on a high quality computer capture of the presentation? If so, how did do it?
Background
We use a HDMI to USB converter to take high resolution video into mimoLive as a source. And we know that a camera pointing at the screen is poor quality - but it does capture the presenter’s laser pointer so we can “see” what they are speaking about.
We use a bright green laser pointer so I am hoping we can reverse-chroma (normally you throw out all the bright green, but in this case we want to keep only the bright green) to capture the spot and then overlay that on the high resolution presentation … and magic, we have a moving laser spot superimposed on a high resolution presentation.
Hey Dean, this is a very cool idea and probably not too hard to implement! I’m sure @“Achim (Boinx)” will have some fun doing this… 
@“Achim (Boinx)” … That would be awesome.
That’s the missing piece to keeping our video recording as high a quality as possible.
This is an interesting idea, but something that would require a camera to be very precisely aimed in order for the overlay to be accurate. Also seems like a very expensive method to overlay a laser pointer onto a presentation, (unless you can get way with a cleverly positioned cheap webcam) because you’re basically throwing away a camera angle just to pull the laser pointer position from the live footage.
If it’s important enough to your workflow that it’s worth doing, I can’t blame you for wanting to do it though. Best of luck on this every interesting endeavor.
@mimolive@deansuhr.us @madden64freak In mimoLive 2.8b2, it should now be possible to do what you want with a bit of tinkering. There is a new “Deskew” filter that lets you fix the distortion you might get when trying to film the projection. If you can control the camera to a point where you can make the slides as dark as possible and the green laser pointer stand out, you can use the Chromakey Basic to remove the slide and just leave the green pointer. You can then overlay this over a grab of the slides via a digitizer.
Achim has only tested this in the “lab”, so if you have a chance to test this in real life, I’d like to know if it works well enough.
Thanks @“Oliver (Boinx)” and @“Achim (Boinx)” … I don’t have any formal events between now and the end of the year … nevertheless I’ll try to set this up and check it out. I need this to work on white/bright slides too so it will be interesting to check out.
In another post you mentioned using Syphon to record to disk something different than we stream. We use an ATEM switcher for our three live cameras and the addition of this new pointer camera means mimoLive is processing three input sources … ATME, screen, and the source PowerPoint/Keynote computer. With the live stream and record to disk being separate encodings that adds yet another load to the computer. I may have to retire my 16GB 2TBSSD MBP17 i&/2.4GHz in favor of a newer MBP with more GPU horsepower this proves to be too much processing load.
@madden64freak - I can aim the camera at the projected image and the camera image should be stable - both images will be the same aspect ratio so this shouldn’t be too difficult and with deskew the overlay should be very good and consistent. We produce medical conferences so the pointer is not for words - it’s about graphs, pictures and MRI’s where it’s important to connect the spoken words with the on-screen slide. It’s not quite a “must have” but it’s a strong “want to have”.
@mimolive@deansuhr.us
In another post you mentioned using Syphon to record to disk something different than we stream. We use an ATEM switcher for our three live cameras and the addition of this new pointer camera means mimoLive is processing three input sources … ATME, screen, and the source PowerPoint/Keynote computer. With the live stream and record to disk being separate encodings that adds yet another load to the computer. I may have to retire my 16GB 2TBSSD MBP17 i&/2.4GHz in favor of a newer MBP with more GPU horsepower this proves to be too much processing load.
If you can upgrade to the new MBP, you should be able to get rid of the ATEM Switcher. We’ve recently conducted tests with the “old” 15" Retina MacBook Pro and were able to process 7 HD SDI signals.
We’ll hopefully be getting our new MBP soon to be able to conduct tests.