Leap Motion C++ Creating a Visual Hand

[gkumagai]

Hey, I have been developing with the Leap Motion for the past month in C++ in Visual Studio.

By the method explained below, I have created a visualization of the hand using the Leap Motion SDK and OpenGL. I was wondering if there is a function I am missing in the Leap motion function to create a hand that resembles the Diagnostic Visualizer in the Leap Motion Control Panel ? Since in my hand, the bone's are not connected and are discontinuous. In contrast, the visualizer has bones that are connected and continuous throughout all ranges of motion.

Diagnostic Visualizer (in Leap Motion Control Panel):

My Hand:

My hand was developed using the following:
- Using bone.length() to determine the length of each bone in the finger (distal, intermediate, proximal, metacarpal) which was used to draw the rectangular prisms
- Each bone's position was determined by using bone.center() and translating the rectangular prism that represents that bone by this vector.
- The orientation of each bone was determined by the following:
fingerTransform = bone.basis();
fingerTransform.toArray4x4(fingerTransform_values);
glPushMatrix();
translate(fingerPipPos);
glMatrixMode(GL_MODELVIEW);
glMultMatrixf(fingerTransform_values);
...
- The spheres for the knuckles were translated by bone.prevJoint()

Thanks!

[Joe_Ward]

I printed out the joint positions of the fingers to be sure, but as you can see the "next joint" of one bone is exactly the same value as the "prev joint" of the next bone.

Finger0
    b0 p:(-72.761330, 182.305008, 39.177826) n:(-72.761330, 182.305008,39.177826)
    b1 p:(-72.761330, 182.305008, 39.177826) n:(-42.698833, 208.338745,19.379961)
    b2 p:(-42.698833, 208.338745, 19.379961) n:(-23.042648, 218.873962,-1.195370)
    b3 p:(-23.042648, 218.873962, -1.195370) n:(-11.299082, 221.120651,-18.249361)
Finger1
    b0 p:(-90.539101, 189.739105, 30.592447) n:(-71.456863, 221.748596,-23.238134)
    b1 p:(-71.456863, 221.748596, -23.238134) n:(-63.430676, 241.529160,-54.957947)
    b2 p:(-63.430676, 241.529160, -54.957947) n:(-46.808094, 240.263443,-68.551216)
    b3 p:(-46.808094, 240.263443, -68.551216) n:(-34.009480, 232.250046,-70.333900)
Finger2
    b0 p:(-96.948830, 183.686417, 24.083649) n:(-83.120163, 208.085281,-31.309366)
    b1 p:(-83.120163, 208.085281, -31.309366) n:(-71.168983, 221.783600,-70.162270)
    b2 p:(-71.168983, 221.783600, -70.162270) n:(-48.916325, 216.777298,-81.125175)
    b3 p:(-48.916325, 216.777298, -81.125175) n:(-35.094444, 208.273865,-77.083992)
Finger3
    b0 p:(-101.621414, 175.526596, 18.504839) n:(-93.539291, 190.972260,-34.443989)
    b1 p:(-93.539291, 190.972260, -34.443989) n:(-68.947914, 191.747131,-65.680099)
    b2 p:(-68.947914, 191.747131, -65.680099) n:(-46.555801, 182.056381,-62.150333)
    b3 p:(-46.555801, 182.056381, -62.150333) n:(-37.389477, 174.728851,-50.370491)
Finger4
    b0 p:(-101.512672, 163.429123, 14.754340) n:(-99.640495, 172.980499,-35.921680)
    b1 p:(-99.640495, 172.980499, -35.921680) n:(-76.165092, 171.429016,-56.819218)
    b2 p:(-76.165092, 171.429016, -56.819218) n:(-62.345840, 167.164444,-47.133331)
    b3 p:(-62.345840, 167.164444, -47.133331) n:(-60.003414, 164.419418,-32.224106)

You can do the same easily enough to verify the data on your end.

Perhaps you are rotating with some translation already, which might cause the bones to rotate around the wrong position?

[DanielGonçalves]

Hey gkumagai
I've made a hand model myself. It's still under construction. All I did was to use the bone joint coordinates using prevJoint and nextJoint functions, as well as the forearm center, and then draw lines connecting the points I wanted. Im sure you can use cilinders or whatever you want instead of lines to make it a better model.
Remember that the thumb has only 3 bones ( the first bone of finger 0 does not exist although it outputs coordinates - I lost a whole day figuring that out xD

Here are some picks of how my model is right now. I simply made a VRML world using Matlab's Simulink and constantly feeding the bone coordinates.

[Yakobom]

Hi. Any chance you could share the code for drawing the hand in c++ and OpenGL? There is no actual working example for this.

[John-snow]

You are really too smart, I can only get a spatial position of a point in MATLAB use leap motion and control the robot model. Do you mind sharing source code? Then it can easy figure the hands in matlab evironment