<< return to Pixycam.com

Identification of variables in hello_world for arduino.

Pixy Software
#1

Hello everyone. I finally managed to connect to the forum.
I’m excited about this project. Congratulations for Pixy.
After giving more than one lap, I managed to understand the meaning of the variables (static int i), (uint16_t blocks). I believe that (i) identifies the corresponding Array to each detected object (blocks) indicates the number of detected objects. Please correct me if not. However I do not quite understand is the role that the variable (j). I beg a little patience for my stupidity and I’m starting and I would deeply understand the meaning of this little program to move forward.

Thanks and regards.

#2

Manuel,

Thanks for trying Pixy. I’m assuming you’re asking about the @‘j’@ variable in the @‘loop’@ method in the ‘hello_world.ino’ arduino example. In this case, the @‘j’@ variable is used as an index to the pixy.blocks array. Whereas, @pixy.blocks[0]@ is the first element in the array, @pixy.blocks[1]@ is the second, and so on.

John

#3

Thanks for your answer John.
I now understand much better the performance of this program.
However, I would like you to confirm me whether the following items are correct:

  • (blocks). Number of detected objects.
  • (i). Identification number of each object. Used to identify the Array.
  • (j). Identification number of a particular Array index.

I have many questions still unanswered. I will start with these:

  • How Pixy assigned the number (i) to recognize each object?
  • In each detection the same number is assigned to a particular object?
  • The identification is always performed by a number?

For now, it is more than enough.
Thanks in advance and best regards.

#4

Hi Manuel,

  • Yes, you are correct that @blocks@ is the number of objects (or “blocks of pixels”) that match a signature.
  • ‘@i@’ is just used as a counter to keep track of how many calls to @pixy.getBlocks();@ we’ve made. Then on the 50th one, we print out the block data to Serial.
  • Yes, ‘@j@’ is used as an index to access all of the blocks in the array.

For your second set of questions:

  • Pixy doesn’t actually assign a number to each object, ‘@i@’ is just used to count how many times we’ve asked Pixy for block data.
  • Please see the description of variable ‘@i@’ above.
  • The distinction between objects is made using @Block.signature@, not ‘@i@’.

Hope this helps.

Scott

#5

Thanks Scott.
Your explanations have helped me a lot. I’m looking forward to receiving my new Pixy to start experimenting with it. I try to run a small project for identification and counting of manufactured products, by color code. This is an implementation of small-scale traceability.

Thanks and I hope to continue with your help. My level is too basic.

#6

Happy to help, Manuel! Feel free to post on the forums or email us with any questions you have.

Scott