Pixy coordinates

Added by Ramesh Warusavitharana 3 months ago

pixy can give the height and width of the detected objects. Also it gives the coordinates as well. But just want to know what are these coordinates. Is it like the center point coordinates of the detected object or something else?


Replies (5)

RE: Pixy coordinates - Added by Jesse French 3 months ago

Hi Ramesh,
The x, y coordinates that Pixy provides indicate the center of the object in camera coordinates (pixels). The width and height are also in camera coordinates (pixels).

Hope this helps!

Jesse

RE: Pixy coordinates - Added by Ramesh Warusavitharana 3 months ago

Well i'm making a length measuring device using pixy. it tracks two led's and get the length between them in pixels then it converts to centimeters. But if i measure a known length and get the length value which unit pixel can represent, it gives different values on different field areas in pixy view field.

what could be the possible reason

(two leds are placed in an inclined surface and pixy is looking at this from the top. PLEASE SEE THE ATTACHED IMAGE)

why is the image is curved? is the camera to high?

image3.png (61.8 kB)

RE: Pixy coordinates - Added by Edward Getz 3 months ago

Hello Ramesh,
The default lens that comes with Pixy is fairly wide field of view, which leads to some distortion. A lens with a longer focal length (narrower field of view) would have less distortion.

http://www.cmucam.org/projects/cmucam5/wiki/Can_I_replace_the_lens_on_Pixy

Hope this helps!

Edward

RE: Pixy coordinates - Added by Ramesh Warusavitharana 3 months ago

Great. Can i use a m12 lens designed for 1/2.3" sensor? We can use higher image sensors larger than 1/4" right?

RE: Pixy coordinates - Added by Jesse French 3 months ago

Hi Ramesh,
It's true that you can use a lens that's designed for a larger sensor. It will give you a narrower field-of-view than the lens claims though, but it shouldn't cause anything bad to happen :)

Jesse

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