opencv-java / object-detection

Object detection in OpenCV and JavaFX: tennis balls recognizer

Object Recognition with OpenCV and JavaFX

Computer Vision course - Politecnico di Torino

A project, made in Eclipse (Neon), for identify and track one or more tennis balls. It performs the detection of the tennis balls upon a webcam video stream by using the color range of the balls, erosion and dilation, and the findContours method. Some screenshots of the running project are available in the screenshots folder.

Please, note that the project is an Eclipse project, made for teaching purposes. Before using it, you need to install the OpenCV library (version 3.x) and JavaFX 8 and create a User Library named opencv that links to the OpenCV jar and native libraries.

A guide for getting started with OpenCV and Java is available at http://opencv-java-tutorials.readthedocs.org/en/latest/index.html.

object-detection's Issues

Assertion failed (m.dims >= 2) at erode

Hi,

I was trying to run the code of the grabFrame method from the ObjRecognitionController class but I'm getting an error when I perform the Imgproc.erode operation:

Mat erodeElement = Imgproc.getStructuringElement(Imgproc.MORPH_RECT, new Size(12, 12));
Imgproc.erode(mask, morphOutput, erodeElement);

The error is:

OpenCV Error: Assertion failed (m.dims >= 2) in cv::Mat::Mat, file C:\builds\master_PackSlaveAddon-win64-vc12-static\opencv\modules\core\src\matrix.cpp, line 454
Exception in thread "main" CvException [org.opencv.core.CvException: cv::Exception: C:\builds\master_PackSlaveAddon-win64-vc12-static\opencv\modules\core\src\matrix.cpp:454: error: (-215) m.dims >= 2 in function cv::Mat::Mat
]
at org.opencv.imgproc.Imgproc.erode_2(Native Method)
at org.opencv.imgproc.Imgproc.erode(Imgproc.java:2007)
at MainMorphological.main(MainMorphological.java:34)

Have you had to deal with this error?do you know what the reason of the error is?

I don't know what the problem is since the mask and morphOutput elements are empty Mats and the erodeElement is exactly the same as the one you're using.

Thanks in advance.