method of depth perception and access to low-level functions - Intel Realsense camera

[Shiva_K_]

For the Intel RealSense camera

Is the camera detecting distances by measuring phase?  If yes, can the phase be modulated and at what frequency?

Or is the pattern being projected enabling detection of distances?  Can the pattern being projected be changed?  What is the intensity and wavelength of the laser (or diode) used?  

We are trying to re-create blood oxygenation in depth in 3-D (i.e. upto a few cm below the skin surface) in order to enable measurement of wound healing as well as brain function.  This camera would be a simple means to do this.  

[Philip_N_]

For the f200 (probably for the others too) the wavelength is in the near infra red range of around 830-870 nm. This will, at best penetrate a couple of mm from the very top layer of skin. There is a nice forum post on one of the stickied posts that has a photo of the structured light coded pattern that is swept across the scene. 

I doubt the f200 would be able to do anything like optical coherence tomography without a lot of extra modification and extra equipment.

[Shiva_K_]

I am looking to do diffuse optical tomography (not optical coherence).  We are using 780nm IR to image upto a few cm at a few mW.  

If the real-sense laser/camera can do phase (or spatial patterning) that I can modulate, AND if the laser is 10mW or more (or if the camera is very sensitive as time passes), then, I should be able to get oxygenation at depths of upto a few cm - which has tremendous applications (from health to gaming).  

If I have access to low level functions (and knowledge of camera capabilities), we should be able to perform the requisite modulation and processing. 

[MartyG]

I don't know what the answer to your technical question is.  I do know that detecting heart-rate with the camera by reading the skin's blood flow color with the IR function was one of the early uses for RealSense suggested by Intel back in May 2014.

What especially interested me about your post was that it was similar to a RealSense idea I'd noted down last week that fell into the category of "I'll probably never use it but I'll record it anyway just in case".  I have a lot of ideas like that    :)

Here's what I wrote in my note.

"The body reacts physiologically to strong belief.  For example, if the player believes that they have taken a strong impact on the hand then the body should respond by sending blood to the affected area where it detected the stimuli in order to compensate for the “injury”.  This could be detected by the camera's IR function and interpreted as a hit on the player in a game."

"This concept could be taken further in a game creation engine such as Unity by constructing an avatar body with simulated blood fluid running through it and a RealSense-controlled heart.  The virtual heart could pump faster in response to IR readings of the player taken by the camera and pump the fluid faster or slower around the avatar body.  The fluid, which could be simulated with a thick stream of particles, could escape from any open wounds in the avatar body's surface."

[Philip_N_]

I'n not sure what the laser power rating is sorry. It is quite a divergent beam however, so even if it is 'high' power it will quickly spread that out at a usable distance to get a reflected signal back.

Have a look at https://software.intel.com/en-us/forums/topic/537872 the stickied post by samontab to get an idea of what can be changed currently.

[samontab]

From the experiments I've made, I think the RealSense camera uses the projected IR pattern to calculate the distance.

Infrared is the spectrum located in this range: 700 nm – 1000 nm. Currently, IR devices in general operate in one of these 3 wavelenghts:

- 720 or 760: Cheapest, and closest to the visible spectrum.

- 850: In between.

- 950: Most expensive, farther away from the visible spectrum

If you look at the projector while it is working you can actually see a faint red glow. This means that it is closer to the visible spectrum, so probably the wavelength is around 720 or 760 nm. This makes sense as they want to make the device as cheap as possible. If they were using 950 nm, you would not be able to see anything while the device is in operation.

Using the provided Intel SDK you can only change two relevant things: the intensity of the projected laser (from 0 to 16 in whatever units these are) and the pattern being projected (choose between 3 different pre programmed types for different levels of accuracy, and how "stretched" is the pattern). So, technically yes, you can change the projected pattern, but in a very limited way.

It would be really useful if we could project anything we want with this camera, but i seriously doubt that Intel is going to release that functionality.