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Pessanha24's profile - activity

2018-08-26 14:39:35 -0500 asked a question OpenGL to cv::cuda::GpuMat

OpenGL to cv::cuda::GpuMat Hi, It is possible to convert a rendered OpenGL object to GpuMat directly without using cv::

2016-07-17 15:06:52 -0500 commented question How to plot the Precision-Recall Curve (PRC) for a Cascade classifier correctly?

Did you solve this problem? I'm obtaining the same results but I don't know why. Thanks

2014-06-13 01:17:48 -0500 asked a question PBO to cv::Mat


Basically I need to render an object using OPENGL and read it back to the CPU for post-processing. I need to make this process as fast as possible since it will be used for object tracking in a particle filtering framework.

Actually I render the object in a window and read it back with success using glReadPixels(), but this is a very slow process.

To increase speed I´m trying to transfer the object data to a PBO, and then transferring it to the CPU in form of a cv::Mat variable (OPENCV)

PBO Initialization:

GLuint pbo;
glBindBuffer(GL_PIXEL_PACK_BUFFER, pbo);
glBufferData(GL_PIXEL_PACK_BUFFER, img.cols*img.rows*3, NULL, GL_DYNAMIC_READ);


glBindBuffer(GL_PIXEL_PACK_BUFFER, pbo);
glReadPixels(0,0, img.cols, img.rows,GL_BGR,GL_UNSIGNED_BYTE,0);

I don't know if I´m doing it right because I try to transfer the PBO to a CV::MAT using glMapBuffer() without success.

Any suggestion or comment will be welcome to help me solve this issue.

If you know a different approach that allows me to obtain speed in this process that help will be "precious".



2013-12-12 20:31:29 -0500 asked a question Contour Vector resize


This is probably a "silly" question, but the successive errors made me come to here.

I want to define my own Contour , so I can use the opencv Function "cv::drawContours".

I don´t want to use the "cv::findContours" function, I only want to add my points (obtained by Alpha Shape) to a - std::vector<std::vector<cv::point>> Contours.

What is the best way to do this? I´m getting successive errors when I try to reserve the correct needed space for my points size.

Thanks to all.

2013-12-11 23:52:25 -0500 received badge  Editor (source)
2013-12-11 23:50:57 -0500 asked a question 2D Point Cloud Contour - Exterior Histogram in Bounding Box


I need some help from you, to find the best solution for my problem.

I have a 2D point cloud (projection from a 3D object), and I need to calculate the histogram from the exterior (Red Area in the example picture) area in the respective bounding box.

I´m new in OPENCV, there is any simple way of doing this? Any function that can help me?

Can you give me some help in this "problem"?

Thanks to all

image description

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2013-09-19 10:53:49 -0500 commented question 3D model read (VRML) - OPENCV Compatibility

I want to read the model and make the 3D to 2D projection using OPENCV. My question is in the best way to load the model and make it available to work in OPENCV.

Do you have some information that can help me?


2013-09-19 09:30:11 -0500 asked a question 3D model read (VRML) - OPENCV Compatibility


I want to read a 3d model (VRML) and work in it using the OPENCV library, so I can make the 3D/2D projection.

Do you know some library that can help me in this task?

Thanks, Nuno Pessanha Santos