Kinect 3D Touch

curoiusbr..

in Contributed Library Questions • 6 months ago

Hi Everyone,

I am using SimpleOpenNi with processing 2.08b. I want to know how to calculate the distance between two objects ? Here in this case I want to calculate the distance between hand and a object.

The first picture shows that depthmap of the scene

Actually what I want to do is that if somehow I can check if I am touching any object or not. Here what I did, I have hand coordinates ( handPosition.x, handPosition.y, handPosition.z) and from the rgb frame ( frame = kinect.rgbImage(); ) I am detecting the depth of the pixel at (handPosition.x, handPosition.y)

-------------------------------------------

// I have a frame size(640,480);

-----------------------

int[] depthvalues = kinect.depth();

int loc = handPosition.x + handPosition.y * 480

int mm = depthvalues[loc];

-------------

if ( abs(mm - handPosition.z ) < threshold )

{

println("You have touched an object");

}

------------------

Problems: handPosition.z gives me some 3 digit values where as mm gives me some 6 digit values. I dont understand why this is happening?

Somewhere I read the handPosition does not repsensts real depth coordinates. it has been converted using this fucntion " convertRealWorldToProjective "

void onCreateHands(int handId, PVector position, float time) {

kinect.convertRealWorldToProjective(position, position);

handPositions.add(position);

}

void onUpdateHands(int handId, PVector position, float time) {

kinect.convertRealWorldToProjective(position, position);

handPositions.add(position);

}

Replies(3)

curoiusbr..

Re: Kinect 3D Touch

6 months ago

If anyone of you didn't understand my question then I am explaining it again.

Problems:

1. Hand coordinates gives me the projected screen coordinate of the Hand where as kinect.depthMap(); gives me Realworld coordinates.

2. I don't somehow this code is working but the only problem is that when I bring my hand in front of any objects it picks the color of the object before touching it

3. What I am doing

a. first tracking the coordinates of the hand in the current frame and passing its 3D coordinates to depthLoc(x,y,z) function

b. depthLoc() function calculates the depth at the location (_x+50,_y+50) which is slightly away from hand's location to avoid the picking color of the hand itself.

c. depthLoc() basically calculating the depth of the pixel at this location and calculating the difference between hand's Z coordinate and the depth calculated at this point (_x+50,_y+50) ....................... [ difference (_z - mm) ] and if this is less then 20 or some threshold then it would pick the color of the object

4. Finally it is not working well it is randomly picking the color I dont know how .

please please please please help

dr.mo

Re: Kinect 3D Touch

6 months ago

i am not going to try to understand your code. from your question i gather that you already know the hand position, so all you need to know is where the object is!!

however, i get the sense that what you mean is ANY object. including a wall? what does touching mean exactly? what happens when you touch an object?

i can imagine, given your approach, that you want to determine this given the distance between an object behind your hand and the hand (both in the z direction). this should be simple if the background and any objects are static. otherwise possibly very hard.

so in the static background case:

1) determine the background without the person - you can ask the person to leave the scene and then just store the depth frame.

2) compute the average depth over a small area (5x5 pixels) in the current depth frame where the hand is, this will somewhat reduce the z -noise in the depth frame.

3). compute the average depth over a small area in the stored background depth frame (over the same are as in 2)

4) compare values from 2) and 3) and if the difference is below a threshold you have a 'touch'

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curoiusbr..

Re: Kinect 3D Touch

5 months ago

Hi Dr.Mo. ,

Here is the video of my working code...

1. Link: http://youtu.be/oWEKS5Opa-o

2. Link: https://www.youtube.com/watch?v=oWEKS5Opa-o

Please have a look and tell me why it is picking the garbage color without touching anything. I am worried if can fix it.

I want it to pick color only when I touch any surface that's all.

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Kinect 3D Touch

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