Advice for Lens M12

[ucacfxt]

Hi there,

we are going to place an order for 8 Slim V100 cameras for a Virtual Reality setup.

The idea is to place the cameras all around a large projection screen (3 x 2.5 meters), looking towards the center (and the user) to perform head and 2 wands tracking. We will be using Rigid Bogy Tracking (three objects)

As we don't care too much about occlusion, we would like to go vor a very wide FOV, so here are some questions:

1) Any experience with Lens M12? Is the calibration going to be ok? Is the software properly compensating for extreme lenses distortion?

2) Are active markers really necessary with this FOV? Or can we try to build IR illuminators with plenty of LEDs shooting in all the directions?

3) Are the WideFOV led in the catalog (LED : Ultra Wide Angle IR 850nm) usable as IR illuminators on the cameras? How many of them would be needed for each camera?

4) It is my understanding that the standard cameras (FlexV100) have strobed IR led ring syncronised to the CMOS sensor to reduce heat generation & maximise brightness. Is it possible to achieve this in some way with the slimv100?

Thanks in advance for your advice!

Franco

[Jim]

Hello:

Your application sounds like a great fit for the Rigid Body Toolkit.

We would tend to recommend the FLEX cameras here, as they will be much easier to setup, having the sync connections and strobes already set for you. The SLIM camera is for OEM applications, but you could certainly use it. Keep in mind that you will have to wire up the sync connection out of the back of the camera. This connector also has the Strobe output, so you could trigger your own IR strobe if needed, but you would have to construct the strobe assembly.

We use M12 lenses all the time, overall we like them, but there are large differences in their quality. When you go lower than 3.5mm, the distortion can be very large, and the software will have a harder time correcting for it. If you use our 4.5mm lens, the distortion will be very low.

Active markers are recommended when you are going over 45 degrees horizontally, as that is the FOV of the IR Strobe we have on the FLEX camera. Yes, you could build your own, and point the IR LEDs in all different directions, or find wider FOV LEDs. I think up to about 60 degrees is okay, for a practical limit. That happens to be about 3.5mm EFL on the lens (to match their FOVs).

I would NOT use our WideFOV LED for illuminators. Their output is about 180 degrees, very wide, which is great for being an Active LED target, but not good for illumination. There are many LED suppliers out there, I can post some if you want.

In general, if you want to take on a project, and understand that it will require some work, then the SLIM sounds like an okay option for you, but if you want an "out of the box" setup, I would really stick with the FLEX V100, as 6 of them would cover your area nicely and track the wands and head really well.

[ucacfxt]

Dear Jim,

Thanks a lot for the info.
So, in short you suggest to stick to FLEX cameras.

One last question then: I've seen that the default lens for the FLEX cameras is 45 degrees, that is very narrow for our setup. Is there any way to purchase FLEX:100 cameras equipped with 60� FOV lenses? Or is there a way to replace the lenses built-in in the FLEX cameras? Last week I was visiting a collegue lab that have it and got the impression that the lenses was blocked.

Thanks in advance for your advice,

Franco

[Jim]

Yes, we can do a special order with 3.5mm lenses on the FLEX product. This will also come with the stock 4.5mm lens, so you can change them out. There is a small set screw that is inside the case, which you can access from the top of the camera, but some people forget to loosen this, and it damages the lenses.

If you use the 3.5mm lens, it will work, but the accuracy of the camera will be less than with the 4.5mm setup.