Back to infra-red tracking ! Request for advice on devices, etc

CitizenJoe

From the archives:

eMTv

Hello again to everyone here..

So.. I've started experimenting and documenting my research on http://vjemtv.online (in French only so far, but planning to make it available in English too soon enough..)

A few questions have arisen, of course..

I'll update this post very soon (luckily tomorrow) since I'm currently gathering all the info we processed during this week's residency devoted to hardware and software research. @Woland or someone else with admin rights on the forum, could you please delete your follow-up and mine, so that we keep this thread tidy ? (yeah, I'm kind of a "neat-square-joints-between-actors" izzy user as well...)

Anyway, i'll definitely be back tomorrow with loads to share with you...

Woland

@emtv said:

1/ Using a

I think maybe you didn't finish what you were typing.

eMTv

@woland said:

<p>@emtv said:</p> <blockquote>1/ Using a</blockquote> <p>I think maybe you didn't finish what you were typing.</p>

Indeed. Sorry for that.. Coming back later !

Fred

@eMTv Hi, some of your questions have been answered but I will chime in with some advice.

For the camera I would go for a security camera, nightshot is actually an enhanced IR mode, it also uses some auto functions to adjust the image so it may not be ideal for tracking when you want camera settings locked. Search SDI box camera on ebay or Ali express, there is a lot and they are cheap. These are very easy to find and very cheap, I would use it over the DSC-F717, especially as it has a more true IR not nightshot.

An example is here:
https://nl.aliexpress.com/item...

They have a night mode aka b/w mode that moves the IR cut filter away from the sensor with a little actuator. They connect with HD-SDI and you can change the lenses (they are cheap cmount and you can find ultra wide lenses for tracking a stage). I have a lot of them in my kit, they are really great things to have and you can make manual settings that persist after power down. Connecting with SDI is a big advantage. You can find hundreds of variations with up to 1080p 60 (although sometimes this is not SMPTE compliant).

you can also step up to a known brand http://www.marshall-usa.com/op... they are basically the same thing as the security cameras, often the same sensors and image processing chip, but with a bit more thoughtful design and some extra features like serial remote for changing settings. Not all have the IR mode.

The Hoya R72 will be fine, but if you go for a camera as I suggested you need to find something that fits on a cmount lens. Also not that the glass in most lenses for cameras is treated to block some IR as well, so security cmount lenses always have IR versions. The 10nm will not make that much difference unless you have an amazing budget for very very specific IR illumination that has a very narrow band.

Take one of the GPU cards out (or sell them and try get a second hand 2080 they are going cheap now) and use a Blackmagic Design DeckLink Duo 2, it will give 2 in and 2 out or 4 in or 4 out 3g SDI signals. It should be installed on an 8x pcie slot and most likely your motherboard has a single 16x slot and an 8x slot (now filled with GPUs) . This is an amazing card and will work seamlessly with Isadora.

I think I have written almost the same post in several threads, Isadora's forum search is pretty lacking. Maybe we can sticky some or have some hot links for threads related to this (and other topics)

eMTv

Hi @Fred and thanks a lot for this detailed post.

We have already let down the idea of using Sony DSC / DSR cameras with nightshot. As far as capturing the IR illuminated scene / persons on stage, we are currently experimenting with a Panasonic VW-BP120 videosurveillance cam (with standard lens) through SDI and a low end Dazzle usb 2.0 capture card, and it's already very promising. We now want to experiment with HD-SDi industrial cameras (since we're already equiped with SDI, that would save us the trouble of ethernet setup, though it's very reliable and permitting long distance connectivity too).

As far as the IR-Pass filter is concerned, I've got a couple of questions :

1/ is it useful with a black and white cam which already has IR vision, or only to cut out the visible light from a colour camera ?

2/ we mentioned here the Lee 87 filter (which I bought and tested +/- successfully, with only one sheet on the black and white Panasonic CCTV cam I just told you about, but maybe I should have splitted and added several layers of it in front of the lens ?) - others also indicated Lee 299 neutral tech filter. What do you think ?

I won't go into much more details right now, because it's already late in the afternoon and we're quitting the theater today, so I need to go pack now, but since I've started documenting the whole thing quite extensively on my website, I'll get my head onto translating it all into English over there, and it'll be a nice and clear way of keeping you guys posted on this reasearch work, as you've all been verey helpful (and I'm thinking also about @Kathmandale on the IR cut discussion topic that I unearthed from the depths of this wonderful Troikatronix community :) )

Take care, and speak soon !

Oh, and thanks for the advice about the Decklink PCI card setup. We won't sell the 2nd graphic card because we need it for another project, but might switch from one to the other depending on what project we're working on or touring !

Fred

All cameras have an IR cut filter built in, IR light will ruin the photos otherwise, unless the camera has an IR mode (sometimes called night mode, and on the cheap sdi security cameras it is called black and white). With no IR cut filter all frequencies of light can reach the sensor. The IR pass filter stops visible light and let's IR pass so the image is only made from IR light. This makes a big difference when doing tracking, visible light on the stage will not alter the image.

eMTv

Hi all, I've eventually translated my latest research insights, including lots of priceless advice coming from your experience feedback, so thank you so much, for I've got a quite clear view of the way I'll handle this..

Please have a look here if you're interested : Real-Time IR Tracking + Body Projection Mapping and don't hesitate to leave some more feedback, over there, and/or in this thread, if/as you wish.

MANY MANY THANKS AGAIN.

Fred

@emtv I had a scan through your notes, don't underestimate the IR pass filter, I would avoid the floppy disk or light filter route, at least compare a proper IR pass filter I have had great success with midwest optics stuff and they have a Cmount filter adaptor https://midopt.com/filters/bp8... floppy disk filters will make your live much harder when it comes to lighting.

Also you are talking about finding paint that doesn't reflect IR, I am guessing so you get good contrast between the bodies and the set. It may be much easier to go the other way, use IR lighting to light the set like crazy and use whatever paint you like, just don't light the bodies with IR, contrast is contrast it doesn't matter which way as you can always invert the image.

eMTv

@fred I mentioned the floppy disk or camera film DIY method for those interested in trying it out, and will do myself out of curiosity, with screen captures of result with each filter.

About finding some paint or material to cut the set / props from IR scene, I believe it would be more appropriate to go this way and not the other way round to achieve our goal in this piece, since we would like the users / actors to be tracked +/- anywhere on the stage...

Fred

@emtv I don't know your set, but often lighting the thing that does not move is easier than lighting the thing that does, so carefully lighting the set with IR and not lighting the stage could be an easier solution. As long as you have good contrast between the set and the actors you can always adjust the image and invert it. I could imagine trying to always light the actors everywhere on stage and not spilling on the set could be more difficult.