Processing Forum

Calculating Angle between two Lines in 3d Space using IMU data & Trigonometry

[0 Replies]
- 10-Aug-2013 12:25 PM
- Forum: Programming Questions
I have 4 points in 3d space: A,B,C,D

These are connected by three lines AB, BC and CD.

What I need:

Yaw and Roll of CD relative to BC

What I know:
Points A,C

Pitch Yaw and Roll of AB and BC

Distance AB and BC

The problem:
I am not really sure. I almost have it all put together, but I get weird artifacts when drawing visualizations. Little things are not behaving as they should (i.e. I believe a line should be horizontal, the numeric output is horizontal, but processing draws it with a slight incline). The problem is that it part of a bigger project and I am having trouble locating the problem. I would like to be able to make sure that my math is solid. If anyone could help me think through this, it would help me a lot.

I will not post the whole code, as I think it might be overkill, but start with the parts which are most critical.

(I am happy to post the rest, if it helps, but at the moment what is most important to me is to know that the following functions are doing what I think they are.)

Step1 - Calculate B

StartingPoint = A

BONE_LENGTH = Distance AB

Endpoint = B
1. PVector CalculateEndPoint()
2. {
3. float endpointY = sin(rotation.y)*BONE_LENGTH;
4. //cos(pitch) = adjecant / hypothenuse
5. //projection is the line AB projected onto the 'ground plane'
6. float projectionXZ = cos(rotation.y)*BONE_LENGTH;
7. //sin(yaw) = opposite / hypotenuse
8. float endpointZ = cos(rotation.x)*projectionXZ;
9. // float eX = sqrt((projectionXZ*projectionXZ)-(eZ*eZ));
10. float endpointX = sin(rotation.x)*projectionXZ;
12. endPoint.set(eX+startingPoint.x, eY+startingPoint.y, eZ+startingPoint.z);
13. return endPoint;
14. }
Step2 - Calculate C

Using the same method as above, jut this time:

StartingPoint = B

BONE_LENGTH = Distance BC

Endpoint = C

Step3a- Calculate yaw between BC and CD

PVector C & D are simply the coordinates of their respective points

(D was given and C I calculated in steps 1 and 2)

Yaw is BCs absolute yaw angle, which i given
1. float GetYaw (PVector C, float yaw BC, PVector D) {
2. return = yaw+ (atan((D.x - C.x)/(D.z - C.z)));
3. }
What I want out of the angle between BC and CD projected down on the floor plane.
Step3b - Calculate difference in roll of BC and pich CD

PVector C & D are simply the coordinates of their respective points

(D was given and C I calculated in steps 1 and 2)

Roll is BCs absolute roll angle
1. float GetRoll (PVector C, float rollBC, PVector D) {
2. return relativeRotation = rollBC- atan((D.y - C.y)/(D.z - C.z));
3. }
I know its sort of wierd talking of roll in this situation. In order to better conceptualize what I want to achieve here, imagine there is a camera hanging on the wall. It is filming an analogue watch which is hanging, somewhat offset, on the oppoite wall. I want to know the angle between the minute pointer and the center of the image.

The center of the image would be my point D. The angle which the minute pointer is at would be my Roll angle.

(and I only know where this imaginary clock is, because I know its at the end of line BC)

Is it clear what I am trying to do here?
*

Does my logic make sense?

Help me optimize my code please (Arduino, Serial & Firmata)

[4 Replies]
- 27-May-2013 08:24 AM
- Forum: Integration and Hardware
Could somebody please glance at my code and tell me if I am making any obvious mistakes? Somehow it is introducing a significant amount of lag, which I cannot account for.

I am using two Arduinos. Arduino1 reads 8 capacitive sensors and sends them to my computer via serial connection. The other Arduino2 is running Firmata and controlls 8 motors.

If I am running the serial consule of Arduino, the readings from Arduino1 appear snappy and fast. In my own software however, it lags behind by ~500ms

Here is the code:
2. //handles the touch issues.
3. // incoming touch is a serial connection, outgoing touch runs via firmata
5. //array for storing incoming values, arranged according to evernote pins??
6. int[] incomingValues = new int[8];
7. //threshholds for deciding whether there is contact or not
8. int[] thresholds = new int[8];
9. //array for storing motor connections
10. int[] motorPins = new int[8];
13. import processing.serial.*; //import the Serial library
14. import cc.arduino.*;
16. Arduino arduino;
18. char end = '\n'; // /nl is the end of the message
19. String incomingString; // the string which is read
20. Serial port; // The serial port
21. String[] a; //string for temporarily storing the incoming values
23. void setup() {
24. println(Arduino.list()); //list all arduinos connected
25. arduino = new Arduino(this, Arduino.list()[3], 57600);
27. port = new Serial(this, Serial.list()[2], 9600);
28. incomingString = port.readStringUntil(end);
29. port.clear(); // function from serial library that throws out the first reading, in case we started reading in the middle of a string from Arduino
30. incomingString = null; // initially, the string will be null (empty)
33. //set all pins as output and set then low
34. for (int i = 0; i <= 13; i++) {
35. arduino.pinMode(i, Arduino.OUTPUT);
36. arduino.digitalWrite(i, Arduino.LOW);
37. }
38. //assign which motor is connected to wich pin (i.e. motor 0 is connected to pin 11)
39. motorPins[0] = 11;
40. motorPins[1] = 10;
41. motorPins[2] = 9;
42. motorPins[3] = 8;
43. motorPins[4] = 7;
44. motorPins[5] = 6;
45. motorPins[6] = 5;
46. motorPins[7] = 3;
47. //assign the thresholds for each sensor (i.e. if sensor 2 has a reading higher then 3 its a contact)
48. thresholds[0] = 1;
49. thresholds[1] = 2;
50. thresholds[2] = 3;
51. thresholds[3] = 2;
52. thresholds[4] = 2;
53. thresholds[5] = 2;
54. thresholds[6] = 2;
55. thresholds[7] = 2;
56. }
58. void draw() {
59. while (port.available () > 0) { //as long as there is data coming from serial port, read it and store it
60. incomingString = port.readStringUntil(end);
61. }
62. if (incomingString != null) { //if the string is not empty
63. a = split(incomingString, ", ");
64. //this is done in order to remap the incoming values so they are in the apropreate order
65. incomingValues[0] =int(a[6]);
66. incomingValues[1] =int(a[7]);
67. incomingValues[2] =int(a[0]);
68. incomingValues[3] =int(a[1]);
69. incomingValues[4] =int(a[2]);
70. incomingValues[5] =int(a[4]);
71. incomingValues[6] =int(a[3]);
72. incomingValues[7] =int(a[5]);
74. //print the values for debugging
76. for (int i = 0; i<8; i++) {
77. print(incomingValues[i]);
78. print(", ");
79. }
80. println();
81. }
83. //set the motors high or low, depending on if there is a touch or not
84. for (int i = 0; i<8; i++) {
85. if (incomingValues[i] - thresholds[i] > 0) {
86. arduino.digitalWrite(motorPins[i], Arduino.HIGH);
87. }
88. else {
89. arduino.digitalWrite(motorPins[i], Arduino.LOW);
90. }
91. }
92. }
Any suggestions on how to improve the code would be welcome. I would prefer not to change the code running on the Arduinos (there is a lot more going on, everything Arduino related is working fine, I am not 100% sure which version of the code is running on them :-/ ...)

Hope you can help me
Cheers

p.

Signal Processing Library

[1 Reply]
- 10-Mar-2012 12:57 PM
- Forum: Library and Tool Development
Hi Everyone

Partly as a programming exercise, and partly becouse I believe it would be useful both for myself and others, I have decided to write a signal processing library.

Right now the idea is that you create a SignalPath for each each sensor value you receive.

If there is an incoming value, you assign it to the Path. The signal is then run through all filters specified.

At the end of the loop you close the signal path. No further filtering will occur until there is another incoming value.

A complete signal path, might look something like this:

(assuming all incoming data is stored in data[] and there is some array of SignalPathes, called accFilter
1. for (int i = 0; i < data.length; i++) {
2. accFilter[i].assign(data[i]);
3. }
5. for (int i = 0; i < accFilter.length; i++) {
6. accFilter[i].offset(250); //i do this, so that the range is in the positive spectrum
7. //accFilter[i].highpass(0.08); //i could do this, if I am only interested in motion, rather than position
8. accFilter[i].lowpass(0.8); //i do this to smoothen the data readings.
9. }
11. // do something here, like some fancy visualization
13. for (int i = 0; i < accFilter.length; i++) {
14. accFilter[i].closePath();
15. }
Ideally there should be a second type of filter which can sort of "fill in the blanks" if the incoming data comes at longer time-intervals.

So far all the filters are functions of the SignalProcessing class. However, I guess in order to use a given filter multiple times, these would actually need a class of their own. I will give that a try, but I am a bit fuzzy on how to do that at this moment.

The complete code I have now is here:
1. ///////////////////////////////////
2. //Signal Processing Class /////////
3. ///////////////////////////////////
5. class SignalPath
6. {
7. float inputSignal = 1; //primary input, signal to be processed
8. float referenceSignal = 1; //secondary input, used as baseline for detecting events etc. (optional)
9. float cleanSignal = 1; //for Lowpassfilter
10. float cleanSignalHighpass = 1; //for highpassfilter
11. boolean touched = false;
13. //constructors
14. SignalPath() {
15. } // Default constructor: keep default value
17. ///////////////////////////////////
18. //Generall Methods ////////////////
19. ///////////////////////////////////
21. //These are generall functions, required to setup your signal chain.
23. //A signal chain is started by assigning it an input.
24. //By doing sow you also set "touched" to false, allowing the filters to do their work
25. void assign(float a) {
26. inputSignal = a;
27. touched = false;
28. }
29. //alternative function, if you wish to also assign a baseline
30. void assign(float a, float b) {
31. inputSignal = a;
32. referenceSignal = b;
33. touched = false;
34. }
36. //a signal chain is ended by reading the output.
37. //this returns the filtered signal
38. //it also prevents any further manipulation of the signal, until a new input is assigned.
39. float read() {
40. return inputSignal;
41. }
43. void closePath() {
44. touched = true;
45. }
47. //checks whether your signal has exceeded a specific threshold
48. boolean readThreshold(float thresh) {
49. if (inputSignal>thresh) {
50. return true;
51. }
52. else {
53. return false;
54. }
55. }
57. //prints out some information. Enter a String to Identify the specific debug message
58. void debug(String txt) {
59. println(txt); //to identify it if there are several
60. println("Input Value: " + inputSignal);
61. println("Touched: " + touched);
62. println("Lowpass Reference: " + cleanSignal);
63. println("Highpass Reference: " + cleanSignalHighpass);
64. println("Baseline Signal: " + referenceSignal);
65. }
69. ///////////////////////////////////
70. //Acutal Filters ////////////////
71. ///////////////////////////////////
73. //LowPass Filter
75. //use this if your signal is very noisy. This will take out extreme spikes
76. //It takes a value between 0 and 1 as parameter (k).
77. //If the parameter is 1, the filter is so weak it has no effect
78. //If the parameter is 0, the filter has maximum effect, but this is quite useless as well
79. //This filter does introduce a slight time delay if the parameter is too high.
81. void lowpass(float k)//signal to be processed, and strength of filter
82. {
83. if (touched == false) {
84. float oldSignal = cleanSignal;
85. cleanSignal = oldSignal + k * (inputSignal - oldSignal);
86. assign(cleanSignal);
87. }
88. }
90. //HighPass Filter
92. //The opposite of the LowPass Filter
93. //Use this, if for some reason you are interested in the noise in your signal.
94. //This also works if you do not care about the actual signal,
95. //but are merely interested in the change in signal
96. void highpass(float a)//signal to be processed, and strength of filter
97. {
98. if (touched == false) {
99. float oldSignal = cleanSignalHighpass;
100. cleanSignalHighpass = oldSignal + a * (inputSignal - oldSignal);
101. assign(cleanSignalHighpass - inputSignal);
102. }
103. }
106. //Offset
107. //Adds a value to the signal
108. void offset(float offsetValue)//signal to be processed, and strength of filter
109. {
110. if (touched == false) {
111. assign(inputSignal + offsetValue);
112. }
113. }
114. }
*

Obviously this is just a start ... this is the first time I have ever written code intended for somebody elses use instead of mine...

I guess I would just like some general feedback:

- Is this useful?

- Does the way I am going about this make sense?

- Any other ways I might implement this?

- Any tips on turning i.e. the lowpass function into an object? Ideally I want the interface to stay as simple as it is now...

- Any algorithms you might want to contribute, or you suggest I look into?

and

- Could somebody point me at a tutorial or something for actually creating a library? to be honest I have no clue on how to actually do that part.

*

Ok, I'll continue playing with this.

Just thought I would lean back and see if I can get some feedback on the way

Cheers

p.

Object data-type

[10 Replies]
- 08-Mar-2012 03:49 PM
- Forum: Programming Questions
Hi everyone

I am using a custom library for some hardware prototypes and am running into an issue which I cant resolve.

One of the functions provided by the library is getDULData(); which returns Object[] as data-type. What I am expecting is an array of integers. However using int() gives me an error, as the int() function does not except the Object datatype.

The library comes with an example, which sadly confuses me even more, and throws an error.

it initiates the veriable "res" like this:
1. Integer[] res=null;
and within draw then assigns the Object[] to it
1. res=dul.getDULData();
When I run the code it says cannot convert Object[] to Integer[]

*
1. Here is the complete code
3. import processing.serial.*;
4. import dulRadio.*;
5. import processing.opengl.*;
6. import de.looksgood.ani.*;
1. DULRadio dul;
2. Integer[] res=null;
3. PGraphics pg;
4. String[] texts=new String[14];
6. void setup() {
7. frameRate(25);
8. size(screen.width, screen.height);
9. pg=createGraphics(screen.width, screen.height,OPENGL);
11. //Replace "COM79" with the COM port you inserted the USB stick into
12. dul=new DULRadio(this, "COM79", 115200, 13);
14. Ani.init(this);
15. }
17. void draw() {
19. pg.beginDraw();
20. pg.background(255);
21. res=dul.getDULData();
23. if (res!=null && res.length==4) {
24. float m=map(res[1], -255, 255, 0.5, 1.5);
25. float m2=map(res[2], -255, 255, 0.5, 1.5);
26. float m3=map(res[3], -255, 255, 0.5, 1.5);
27. pg.translate(width/2, height/2);
28. pg.pushMatrix();
29. pg.rotateZ(PI*m);
30. pg.rotateX(PI*m2);
31. pg.rotateY(PI*m3);
32. pg.box(100);
33. pg.popMatrix();
34. }
35. pg.endDraw();
36. }
More infos to what this is about can be found here: http://www.digitalurbanliving.dk/news/news/dul-radio.php

Its actually pretty cool :-)

*

If anyone could give me some tip on how to sort out my data-issues, I would be really grateful

Thanks

p.

Placing images with dynamic distances to eachother

[5 Replies]
- 28-Dec-2011 04:03 AM
- Forum: Programming Questions
Hi Everyone

I would like some pointers on how to approach a problem. I intend to write an android app using processing. Its for a demo, it just needs to look nice once - I am not destributing it or anything.

Here is the part that I am not sure how to approach as of yet:

I want to place multiple icons on the display.

The number of icons is not fixed and can change depending on other parameters.

The icons need to be placed randomly (or appear to be placed randomly) and should be evenly spaced.

Now comes the tricky part:

At some point, a rectangle will enter the display, reducing the size of the area which is available for the icons.

The icons should move and dynamically rearrange in order to make up for the reduced space.

*

If anyone has some suggestions on how they would approach this, I would be very thankful. I did not find any library that does what I want, though some of the wordcloud applications come close. I sort of hope that there is some library or tutorial floating around which might help me. I didnt find anything though :-/

Anyway. Any help is apreceated.

p.

Please explain what this error message means to me

[0 Replies]
- 05-Oct-2011 12:19 PM
- Forum: Programming Questions
FATAL EXCEPTION: Thread-11
java.lang.NoSuchMethodError: processing.core.PApplet.loadImage
at com.modestmaps.InteractiveMap$TileLoader.run(InteractiveMap.java:457)
at java.lang.Thread.run(Thread.java:1020)

What I *think* I understand:

InteractiveMap$TileLoader is calling on a method loadImage.
loadImage should be a method within PApplet.java, however for some reason it does not exist.
Becouse of this, the program crashes.

Now, what more information can I find in this message? What do all the numbers mean? Are they referring to lines of coad?

What does Thread 11 mean?

*

Next step: How would I go about fixing this?

Its an android application - if you know anything about Android & Processing, I have a more detailed post here, and would appreceate help: http://forum.processing.org/topic/modest-maps-android-help-me-fix-error

(I know I technically am cross posting here, however with this post I am just hoping for some generall help with interpreting the error message, rather than a solution to my problem, so I hope you will tolerate this.)

Thanks for any input

P.

modest maps & android --> help me fix error

[1 Reply]
- 05-Oct-2011 10:08 AM
- Forum: Android Processing
Hi Everyone

I am a bit of an amateur programmer, so I might be missing something obvious.

I am trying to run the processing version of modest maps ( http://www.tom-carden.co.uk/2008/02/18/modest-maps-vs-processing/) on my android device.

When I run my code (simplified to the bare essentials) I get following error message:

FATAL EXCEPTION: Thread-13
java.lang.NoSuchMethodError: processing.core.PApplet.loadImage
at com.modestmaps.InteractiveMap$TileLoader.run(InteractiveMap.java:457)
at java.lang.Thread.run(Thread.java:1020)

This is my code, it is the code from the website, however I removed all interactions and the gui.
1. //
  // This is a test of the interactive Modest Maps library for Processing
  // the modestmaps.jar in the code folder of this sketch might not be
  // entirely up to date - you have been warned!
  //
  
  // this is the only bit that's needed to show a map:
  InteractiveMap map;
  
  void setup() {
  
  // create a new map, optionally specify a provider
  map = new InteractiveMap(this, new Microsoft.AerialProvider());
  // others would be "new Microsoft.HybridProvider()" or "new Microsoft.RoadProvider()"
  // the Google ones get blocked after a few hundred tiles
  // the Yahoo ones look terrible because they're not 256px squares :)
  
  }
  
  void draw() {
  background(0);
  
  // draw the map:
  map.draw();
  // (that's it! really... everything else is interactions now)
  
  }
Does anyone have any suggestions on how to go about solving my problem?

Any help would be appreceated

Thanks

p.

EDIT:

My guess is that depending on whether its regular processing or android processing, that it refers to a different PApplet.java file. However, I have no clue whether that makes sense, or how to do anything about it, if that is the problem.

http://code.google.com/p/ processing/source/browse/ trunk/processing/android/core/ src/processing/core/PApplet. java?r=7046
http://code.google.com/p/ processing/source/browse/ trunk/processing/core/src/ processing/core/PApplet.java? r=7046

OSC & Android (solved)

[0 Replies]
- 03-Oct-2011 03:05 PM
- Forum: Android Processing
solved

EDIT: I thought OSC didnt work on my android - realized it was a simple typo in my code which made things go whack. oscP5 seems to work perfectly with android :-)

How to optimize complex if statement

[2 Replies]
- 24-Aug-2011 10:39 PM
- Forum: Programming Questions
I have this beast in my code:
1. if(pixel[0][5] < 800 || pixel[0][6] < 800 || pixel[0][4] < 800 ||
2. pixel[1][4] < 800 || pixel[1][5] < 800 || pixel[1][6] < 800 || pixel[1][7] < 800 || pixel[1][3] < 800 ||
3. pixel[2][4] < 800 || pixel[2][5] < 800 || pixel[2][6] < 800 || pixel[2][7] < 800 || pixel[2][3] < 900||
4. pixel[3][4] < 800 || pixel[3][5] < 800 || pixel[3][6] < 800 || pixel[3][7] < 800 || pixel[3][3] < 800 ||
5. pixel[4][5] < 800 || pixel[4][6] < 800 || pixel[4][7] < 800)
6. { do something }
any suggestions on how to simplify this?

context: I have a large array of data, and need to trigger certain actions when one value of a specific group reaches a certain number.

If someone could suggest a better way of 'asking' this, that would be amazing. (or point me to a tutorial)

Thanks

p.

Processing and Autodesk Maya

[0 Replies]
- 13-Apr-2011 08:48 AM
- Forum: General Discussion
Hi There

I am wondering, has anyone here ever used a processing sketch for creating an interactive texture on a 3d object rendered in Maya?

If so, could you give me tips on how to go about it?

Or even if not, do you have any ideas on how I would tackle this?

Thanks for any input

Cheers

p.

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