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2016-12-29 14:32:49 -0600 commented question Problem compiling Opencv 2.4.8 - cudaarithm.a linking

Here, the same problem... Ubuntu 16.04.1 OpenCV 3.2.0-dev

How come??? Wield...
2016-09-27 19:31:45 -0600 commented question OpenCV-git with OpenCL ?

jiapei:~$ nvcc --version nvcc: NVIDIA (R) Cuda compiler driver Copyright (c) 2005-2016 NVIDIA Corporation Built on Fri_Jul_15_14:46:45_CDT_2016 Cuda compilation tools, release 8.0, V8.0.33
2016-09-27 19:31:42 -0600 commented question OpenCV-git with OpenCL ?

jiapei:~$ nvidia-smi Tue Sep 27 17:22:50 2016
+-----------------------------------------------------------------------------+ | NVIDIA-SMI 367.44 Driver Version: 367.44 | |-------------------------------+----------------------+----------------------+ | GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC | | Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. | |===============================+======================+======================| | 0 GeForce GTX 980M Off | 0000:01:00.0 On | N/A | | N/A 42C P8 7W / N/A | 379MiB / 4029MiB | 1% Default | +-------------------------------+----------------------+----------------------+
2016-09-27 19:31:38 -0600 commented question OpenCV-git with OpenCL ?

My Cuda is of version 8.0.34, and Cuda comes with OpenCL libOpenCL.so.1.0.0 by default. I agree with you Tetragramm. I just wanted to express NVidia implementation of OpenCL is of version 1.0.0, but it seems OpenCV-git is ONLY compatible with OpenCL version 2.x ????
2016-09-27 16:19:47 -0600 asked a question OpenCV-git with OpenCL ?

At the very beginning, my working environment:

jiapei:~$ nvidia-smi Tue Sep 27 17:22:50 2016
+-----------------------------------------------------------------------------+ | NVIDIA-SMI 367.44
Driver Version: 367.44
| |-------------------------------+----------------------+----------------------+ | GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC | | Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. | |===============================+======================+======================| | 0 GeForce GTX 980M Off | 0000:01:00.0 On |
N/A | | N/A 42C P8 7W / N/A | 379MiB / 4029MiB | 1%
Default | +-------------------------------+----------------------+----------------------+

+-----------------------------------------------------------------------------+ | Processes:
GPU Memory | | GPU PID Type Process name
Usage | |=============================================================================| | 0 1099 G
/usr/lib/xorg/Xorg
187MiB | | 0 2838 G
compiz
109MiB | | 0 4202 G
...s-passed-by-fd --v8-snapshot-passed-by-fd 81MiB | +-----------------------------------------------------------------------------+

jiapei:~$ nvcc --version nvcc: NVIDIA

(R) Cuda compiler driver Copyright (c) 2005-2016 NVIDIA Corporation Built on Fri_Jul_15_14:46:45_CDT_2016 Cuda compilation tools, release 8.0, V8.0.33

  1. If I enable Cuda OpenCL, it seems Cuda OpenCL is of version 1.x, and it seems current OpenCV-git nees OpenCL 2.x ?????

  2. I activelly didn't activate anythhing related to OpenCL, but still obtained the following error message.

[ 39%] Linking CXX shared library ../../lib/libopencv_cudaimgproc.so cd /home/jiapei/Downloads/computervision/opencv/build/modules/cudaimgproc && /usr/bin/cmake -E cmake_link_script CMakeFiles/opencv_cudaimgproc.dir/link.txt --verbose=1 /usr/bin/c++ -fPIC -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Winit-self -Wpointer-arith -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fno-omit-frame-pointer -ffast-math -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -pg -g -fvisibility=hidden -fvisibility-inlines-hidden -fopenmp -Wno-undef -Wno-missing-declarations -Wno-shadow -Wno-unused-parameter -O3 -DNDEBUG -DNDEBUG -shared -Wl,-soname,libopencv_cudaimgproc.so.3.1 -o ../../lib/libopencv_cudaimgproc.so.3.1.0 CMakeFiles/opencv_cudaimgproc.dir/src/hough_circles.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/match_template.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/gftt.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/blend.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/canny.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/histogram.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/bilateral_filter.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/generalized_hough.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/corners.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/hough_lines.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/color.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/mssegmentation.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/mean_shift.cpp.o CMakeFiles/opencv_cudaimgproc.dir/src/hough_segments.cpp.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_corners.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_blend.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_hough_circles.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_clahe.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_color.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_debayer.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_hough_lines.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_mean_shift.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_canny.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_bilateral_filter.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_generalized_hough.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_hist.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_match_template.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_build_point_list.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_hough_segments.cu.o CMakeFiles/cuda_compile.dir/src/cuda/cuda_compile_generated_gftt.cu.o -L/usr/local/cuda-8.0/lib64 ../../lib/libopencv_cudafilters.so.3.1.0 -ldl -lm -lpthread -lrt -lGLU -lGL -llapack -lf77blas ...

(more)
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2014-09-03 23:07:53 -0600 asked a question Build OpenCV 3.0 with Visual Studio 2013 ?

Fail to build Hi, all:

OS: Windows 8.1 IDE: VS2013 (VC12) OpenCV: 3.0-alpha Cuda: 6.5

I just don't want to use those built libraries already extracted from 3.0-alpha, but I really hope to use the libraries built manually. Therefore, I used CMake 3.0.1 to have everything configured and generate the entire solution for OpenCV 3.0 alpha.

However, when I tried to build the core module, namely, opencv_core, I obtained the following error message:

4>  'ptxas' is not recognized as an internal or external command,
4>  operable program or batch file.
4>  gpu_mat.cu

4>  CMake Error at cuda_compile_generated_gpu_mat.cu.obj.cmake:264 (message):
4>    Error generating file
4>    C:/Packages/computervision/opencv-3.0.0/rebuild/modules/core/CMakeFiles/cuda_compile.dir/src/cuda/Debug/cuda_compile_generated_gpu_mat.cu.obj


4>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V120\Microsoft.CppCommon.targets(170,5): error MSB6006: "cmd.exe" exited with code 1.

It looks like VS2013 is not able to produce .cu.obj file correctly. Can anybody give me a hand?

Thank you ... Best Regards Pei
2013-07-29 12:02:21 -0600 asked a question OpenCV 2.4.6.1 CMake Errors...

Hi, all:

Environment: Ubuntu 13.04 + OpenCV 2.4.6.1

CMake Errors in build/CMakeFiles/CMakeError.log are briefly summarized as: 1. linux/videodev.h:No such file or directory 2. sys/videoio.h:No such file or directory 3. ffmpeg/avformat.h: No such file or directory

I did a brief investigation,

  1. ./modules/highgui/src/cap_libv4l.cpp : #include <linux/videodev.h> ./modules/highgui/src/cap_v4l.cpp : #include <linux/videodev.h>
  2. ./modules/highgui/src/cap_v4l.cpp : #include <sys/videoio.h>
  3. modules/highgui/src/ffmpeg_codecs.hpp : #include <ffmpeg/avformat.h>

Conclusions can be drawn as:

  1. HAVE_CAMV4L, HAVE_CAMV4L2, HAVE_VIDEOIO should be exclusively defined. For instance, in my case, Ubuntu 13.04 corresponds to HAVE_CAMV4L2. When I do ccmake ../ -- the out of source build, where can I specify it's HAVE_CAMV4L, HAVE_CAMV4L2 or HAVE_VIDEOIO?
  2. I didn't use the default ffmpeg installed from the default Ubuntu 13.04 repository, but use the most recent ffmpeg 2.0 instead. It seems I've got /usr/include/libavformat/avformat.h, but not ffmpeg/avformat.h. How can I specify, I'm having HAVE_LIBAVFORMAT_AVFORMAT_H instead of HAVE_FFMPEG_AVFORMAT_H ?

Cheers Pei
2013-07-29 08:58:11 -0600 commented question OpenCV 2.4.6.1 OpenNI 2.2 missing OPENNI_PRIME_SENSOR_MODULE_BIN_DIR

Now, there seems to be a bit progress. The only issue is now:

* WARNING, PrimeSensor Module binaries directory (set by OPENNI_PRIME_SENSOR_MODULE_BIN_DIR variable) is not found or does not have PrimeSensor Module binaries. *
2013-07-29 06:03:07 -0600 commented question OpenCV 2.4.6.1 OpenNI 2.2 missing OPENNI_PRIME_SENSOR_MODULE_BIN_DIR

Hi, Steven: I've tried what you said already. My OpenNI 2.2 is now put under /opt/OpenNI-Linux-x86-2.2,

> :/opt/OpenNI-Linux-x86-2.2$ ls > Documentation install.sh NOTICE primesense-usb.rules Samples > Include LICENSE OpenNIDevEnvironment Redist Tools

and, I did modify OPENNI_INCLUDES and OPENNI_LIBRARY respectively to /opt/OpenNI-Linux-x86-2.2/Include and /opt/OpenNI-Linux-x86-2.2/Redist and made sure everything I could do already. However, problem continues... Also, still, how to set OPENNI_PRIME_SENSOR_MODULE and OPENNI_PRIME_SENSOR_MODULE_BIN for OpenNI 2.2????
2013-07-28 22:29:15 -0600 asked a question OpenCV 2.4.6.1 OpenNI 2.2 missing OPENNI_PRIME_SENSOR_MODULE_BIN_DIR

Hi, all:

Environment Ubuntu 13.04 OpenCV 2.4.6.1 OpenNI 2.2

Always got the warning while building OpenCV 2.4.6.1, with the following warning messages

WARNING, OpenNI library directory (set by OPENNI_LIB_DIR variable) is not found or does not have OpenNI libraries.

WARNING, OpenNI include directory (set by OPENNI_INCLUDE_DIR variable) is not found or does not have OpenNI include files.

WARNING, PrimeSensor Module binaries directory (set by OPENNI_PRIME_SENSOR_MODULE_BIN_DIR variable) is not found or does not have PrimeSensor Module binaries.

As said here http://community.openni.org/openni/topics/compiling_opencv_with_openni_2, OpenCV now only implemented a wrapper for OpenNI 1.X, but not OpenNI 2.2 ...

How to make OpenCV 2.4.6.1 be able to built with OpenNI 2.2?

Cheers Pei
2013-07-25 19:35:20 -0600 commented answer Built-in camera not automatically detected in OpenCv 2.4.2 with OpenNI

Hi, Steven, Thank you for your prompt reply. Yup, now, I upgraded to OpenCV 2.4.6.1 However, I don't know why cheese is not able to detect Kinect but with lsusb Bus 002 Device 009: ID 045e:02ad Microsoft Corp. Xbox NUI Audio Bus 002 Device 008: ID 045e:02b0 Microsoft Corp. Xbox NUI Motor Bus 002 Device 010: ID 045e:02ae Microsoft Corp. Xbox NUI Camera

Now, OpenCV 2.4.6.1 is able to start capturing from the Logitech C920 . Does that mean, I need to re-install OpenNI? oh, I'm using OpenNI 1.5.4, do I have to upgrade it to OpenNI 2.2 ?

Thanks again.
2013-07-23 21:12:23 -0600 asked a question CvCapture_OpenNI::CvCapture_OpenNI : Failed to enumerate production trees: Can't create any node of the requested type!

Hi, all:

Environment： Ubuntu 13.04 + OpenCV 2.4.6 + OpenNI 1.5.4

Testing my simple code, but obtained the following error message:

Opened device HD Pro Webcam C920 successfully (handle = 1) Done. CvCapture_OpenNI::CvCapture_OpenNI : Failed to enumerate production trees: Can't create any node of the requested type! Sorry, fail to open the webcam! Exit! 0 0 0 0 0

I'm wondering if it's possible for me to specify the user-specified way to open a camera? I only have my Logitech C920 connected to the computer, but why OpenCV 2.4.6 tries to open the camera with OpenNI? I would like to use unicap to open my C920, instead of using OpenNI how to do that?

Cheers Pei
2013-07-23 05:00:09 -0600 answered a question Built-in camera not automatically detected in OpenCv 2.4.2 with OpenNI

I've got exactly the same problem as asked here. I'm using Ubuntu 13.04 + OpenNI 1.5.4 with a Kinect.

Do you have a solution now?

Best Regards Pei
2013-07-10 10:23:43 -0600 asked a question Detect Corners Using cornerHarris ?

Hi, all:

Sorry to ask such a naive question, but it does keep me annoying I'm trying to see the Harris Corner effect using the modified code here https://code.ros.org/trac/opencv/browser/trunk/opencv/samples/cpp/tutorial_code/TrackingMotion/cornerHarris_Demo.cpp?rev=5982 with my Logitech USB camera. However, from time to time, the code in the above linkage looks on all the pixels inside the captured image as corners ---- namely, a picture full of corners. Does anybody meet the same situation? How can we avoid such "all pixels are corners" situation?

Best Regards Pei
2013-06-24 19:21:46 -0600 asked a question Not all tools are enabled in OpenCV4Android ?

Hi, all:

One more naive question. I strictly followed http://code.opencv.org/projects/opencv/wiki/Building_OpenCV4Android_from_trunk trying to build my own OpenCV4Android. Quite different from the configuration of OpenCV for my desktop, now none of TBB, OpenCL, OpenGL, GTK is enabled. So, my question is: 1) Should all these tools be ignored in OpenCV4Android ? I mean, maybe, the default Android doesn't come with these packages, and Android has already ignored these packages by itself? 2) Is there a way for me to configure the settings so that I can enable those tools, as what I've done for OpenCV 4 Desktop? 3) Why Eigen is automatically enabled when configuring OpenCV4Android?

Cheers Pei

$ sh ./scripts/cmake_android.sh -- Detected version of GNU GCC: 47 (407) -- Performing Test HAVE_CXX_W -- Performing Test HAVE_CXX_W - Success -- Performing Test HAVE_C_W -- Performing Test HAVE_C_W - Success -- Performing Test HAVE_CXX_WALL -- Performing Test HAVE_CXX_WALL - Success -- Performing Test HAVE_C_WALL -- Performing Test HAVE_C_WALL - Success -- Performing Test HAVE_CXX_WERROR_RETURN_TYPE -- Performing Test HAVE_CXX_WERROR_RETURN_TYPE - Success -- Performing Test HAVE_C_WERROR_RETURN_TYPE -- Performing Test HAVE_C_WERROR_RETURN_TYPE - Success -- Performing Test HAVE_CXX_WERROR_ADDRESS -- Performing Test HAVE_CXX_WERROR_ADDRESS - Success -- Performing Test HAVE_C_WERROR_ADDRESS -- Performing Test HAVE_C_WERROR_ADDRESS - Success -- Performing Test HAVE_CXX_WERROR_SEQUENCE_POINT -- Performing Test HAVE_CXX_WERROR_SEQUENCE_POINT - Success -- Performing Test HAVE_C_WERROR_SEQUENCE_POINT -- Performing Test HAVE_C_WERROR_SEQUENCE_POINT - Success -- Performing Test HAVE_CXX_WFORMAT -- Performing Test HAVE_CXX_WFORMAT - Success -- Performing Test HAVE_C_WFORMAT -- Performing Test HAVE_C_WFORMAT - Success -- Performing Test HAVE_CXX_WERROR_FORMAT_SECURITY -- Performing Test HAVE_CXX_WERROR_FORMAT_SECURITY - Success -- Performing Test HAVE_C_WERROR_FORMAT_SECURITY -- Performing Test HAVE_C_WERROR_FORMAT_SECURITY - Success -- Performing Test HAVE_CXX_WMISSING_DECLARATIONS -- Performing Test HAVE_CXX_WMISSING_DECLARATIONS - Success -- Performing Test HAVE_C_WMISSING_DECLARATIONS -- Performing Test HAVE_C_WMISSING_DECLARATIONS - Success -- Performing Test HAVE_CXX_WMISSING_PROTOTYPES -- Performing Test HAVE_CXX_WMISSING_PROTOTYPES - Failed -- Performing Test HAVE_C_WMISSING_PROTOTYPES -- Performing Test HAVE_C_WMISSING_PROTOTYPES - Success -- Performing Test HAVE_CXX_WSTRICT_PROTOTYPES -- Performing Test HAVE_CXX_WSTRICT_PROTOTYPES - Failed -- Performing Test HAVE_C_WSTRICT_PROTOTYPES -- Performing Test HAVE_C_WSTRICT_PROTOTYPES - Success -- Performing Test HAVE_CXX_WUNDEF -- Performing Test HAVE_CXX_WUNDEF - Success -- Performing Test HAVE_C_WUNDEF -- Performing Test HAVE_C_WUNDEF - Success -- Performing Test HAVE_CXX_WINIT_SELF -- Performing Test HAVE_CXX_WINIT_SELF - Success -- Performing Test HAVE_C_WINIT_SELF -- Performing Test HAVE_C_WINIT_SELF - Success -- Performing Test HAVE_CXX_WPOINTER_ARITH -- Performing Test HAVE_CXX_WPOINTER_ARITH - Success -- Performing Test HAVE_C_WPOINTER_ARITH -- Performing Test HAVE_C_WPOINTER_ARITH - Success -- Performing Test HAVE_CXX_WSHADOW -- Performing Test HAVE_CXX_WSHADOW - Success -- Performing Test HAVE_C_WSHADOW -- Performing Test HAVE_C_WSHADOW - Success -- Performing Test HAVE_CXX_WSIGN_PROMO -- Performing Test HAVE_CXX_WSIGN_PROMO - Success -- Performing Test HAVE_C_WSIGN_PROMO -- Performing Test HAVE_C_WSIGN_PROMO - Failed -- Performing Test HAVE_CXX_WNO_NARROWING -- Performing Test HAVE_CXX_WNO_NARROWING - Success -- Performing Test HAVE_C_WNO_NARROWING -- Performing Test HAVE_C_WNO_NARROWING - Success -- Performing Test HAVE_CXX_WNO_DELETE_NON_VIRTUAL_DTOR -- Performing Test HAVE_CXX_WNO_DELETE_NON_VIRTUAL_DTOR - Success -- Performing Test HAVE_C_WNO_DELETE_NON_VIRTUAL_DTOR -- Performing Test HAVE_C_WNO_DELETE_NON_VIRTUAL_DTOR - Failed -- Performing Test HAVE_CXX_WNO_UNNAMED_TYPE_TEMPLATE_ARGS -- Performing Test HAVE_CXX_WNO_UNNAMED_TYPE_TEMPLATE_ARGS - Failed -- Performing Test HAVE_C_WNO_UNNAMED_TYPE_TEMPLATE_ARGS -- Performing Test HAVE_C_WNO_UNNAMED_TYPE_TEMPLATE_ARGS - Failed -- Performing Test HAVE_CXX_FDIAGNOSTICS_SHOW_OPTION -- Performing Test HAVE_CXX_FDIAGNOSTICS_SHOW_OPTION - Success -- Performing Test HAVE_C_FDIAGNOSTICS_SHOW_OPTION -- Performing Test HAVE_C_FDIAGNOSTICS_SHOW_OPTION - Success -- Performing Test HAVE_CXX_FOMIT_FRAME_POINTER -- Performing Test HAVE_CXX_FOMIT_FRAME_POINTER - Success -- Performing Test HAVE_C_FOMIT_FRAME_POINTER -- Performing Test HAVE_C_FOMIT_FRAME_POINTER - Success -- Looking for alloca.h -- Looking for alloca.h - found -- Looking for alloca -- Looking for alloca - not found -- Looking for unistd.h -- Looking for unistd.h - found -- Looking for pthread.h -- Looking for pthread.h - found -- Found ZLIB: /home/pei/Android/android-ndk-r8e/platforms/android-8/arch-arm/usr/lib/libz.so (found version "1.2.3") -- Looking for assert.h -- Looking for assert.h - found -- Looking for fcntl.h -- Looking for fcntl.h - found -- Looking for io.h -- Looking for io.h - not found -- Looking for jbg_newlen -- Looking for jbg_newlen - not found -- Looking for mmap -- Looking for mmap ... (more)
2013-04-15 03:56:38 -0600 received badge ● Editor (source)
2013-04-15 03:54:51 -0600 asked a question Enable AMD OpenCL for OpenCV 2.4.5 .

Hi, all:

Long time no see. ^_^

Environment:

  1. Ubuntu 12.10

  2. OpenCV 2.4.5

  3. AMDAPP: AMD-APP-SDK-v2.8-lnx32

  4. Video Card: AMD 6870

I'm trying to play OpenCL with OpenCV 2.4.5. I defaultly installed AMDAPP under /opt/AMDAPP

And while I do a out-of-folder build for OpenCV, I set

  1. OPENCL_ROOT_DIR /opt/AMDAPP/include (this seems to be correct)
  2. OpenCL_DIR OpenCL_DIR-NOTFOUND (always showing NOTFOUND)

I tried to let

  • OpenCL_DIR = /opt/AMDAPP/include
  • OpenCL_DIR = /opt/AMDAPP etc. but nothing worked ever.

My question is: what is OpenCL_DIR if I use a AMD video card and related packages, instead of a NVidia one? Besides AMDAPP, is there anything else that I need to install for OpenCL?

Thank you..

Best Regards Pei
2013-03-05 12:25:21 -0600 received badge ● Student (source)
2013-02-13 17:24:16 -0600 asked a question OpenCV VideoCapture.open() IP Camera unstable...

Hi, all:

Environment: OS: Ubuntu 12.10 OpenCV: 2.4.9 SVN

VideoCapture.open(URL) sometimes successfully open the IP camera and starts streaming from URL. However, it's not very stable. Sometimes, it fails. The most probable reason is: the streaming from the certain URL hasn't closed the connection yet.

Any recommendations to open an IP camera stream (URL) ? Maybe, not use OpenCV to do this?

Cheers Pei
2013-02-13 16:47:07 -0600 answered a question How to open VideoCapture twice?

Thanks... Sorry for this naive question.. ^_^ Close the topic please...
2013-02-07 21:46:49 -0600 asked a question How to open VideoCapture twice?

Hi, all:

I would like to open VideoCapture twice. 1) The first time, scan all existing VideoCapture devices. 2) The second time, use some certain capture device to start capturing.

Code patch is attached.

unsigned int num = 0;
cv::VideoCapture cap;
while(true)
{
    cap.open(num++);
    if(!cap.isOpened())
        break;
    cap.release();
}
num--;

Mat frame;
cap.open(num-1);
cap >> frame;
cv::imwrite("test.jpg", frame);

I couldn't see anything wrong that I've done. But, I failed to retrieve a frame, and of course, what I saved is not a non-jpg file -- just nothing .

Can anybody help please?

Cheers Pei
2013-02-07 04:25:34 -0600 asked a question How to get a camera's UUID?

Hi, all:

I'm wondering if it's possible for me to get the camera's UUID by using OpenCV VideoCapture in C++ ? Or, is there any other recommended package to summarize all connected cameras that be able to provide more info upon VideoCapture ?

Cheers Pei
2013-01-28 05:13:34 -0600 answered a question How do I access an IP Camera?

This works for me under Windows7 + OpenCV 2.4.3
2013-01-27 15:59:14 -0600 answered a question SimpleBlobDetector and blob contours

Exactly. I've got exactly the same question to ask. It seems there used to be a function called detectEx, which is able to return the contours directly... Weird...
2012-12-20 01:44:13 -0600 asked a question OpenCV Android, testing on a Galaxy S1...

Hi, all:

I just clicked OCV T2 Use OpenCV on my Galaxy S1, but received all the following error message from LogCat. Any suggestions?

12-19 23:35:53.056: I/OCVSample::Activity(6226): Instantiated new class org.opencv.samples.tutorial2.Sample2NativeCamera 12-19 23:35:53.060: I/OCVSample::Activity(6226): called onCreate 12-19 23:35:53.080: D/CameraBridge(6226): Attr count: 3 12-19 23:35:53.099: D/OpenCVManager/Helper(6226): Service connection created 12-19 23:35:53.103: D/OpenCVManager/Helper(6226): Trying to get library path 12-19 23:35:53.290: D/OpenCVManager/Helper(6226): Trying to get library list 12-19 23:35:53.458: D/OpenCVManager/Helper(6226): Library list: "" 12-19 23:35:53.458: D/OpenCVManager/Helper(6226): First attempt to load libs 12-19 23:35:53.458: D/OpenCVManager/Helper(6226): Trying to init OpenCV libs 12-19 23:35:53.458: D/OpenCVManager/Helper(6226): Trying to load library /data/data/org.opencv.engine/lib/libopencv_java.so 12-19 23:35:53.458: D/dalvikvm(6226): Trying to load lib /data/data/org.opencv.engine/lib/libopencv_java.so 0x47ad3fa0 12-19 23:35:53.498: D/dalvikvm(6226): Added shared lib /data/data/org.opencv.engine/lib/libopencv_java.so 0x47ad3fa0 12-19 23:35:53.498: D/OpenCVManager/Helper(6226): OpenCV libs init was ok! 12-19 23:35:53.498: D/OpenCVManager/Helper(6226): First attempt to load libs is OK 12-19 23:35:53.498: D/OpenCVManager/Helper(6226): Init finished with status 0 12-19 23:35:53.498: D/OpenCVManager/Helper(6226): Unbind from service 12-19 23:35:53.501: D/OpenCVManager/Helper(6226): Calling using callback 12-19 23:35:53.501: I/OCVSample::Activity(6226): OpenCV loaded successfully 12-19 23:35:53.548: D/CameraBridge(6226): call surfaceChanged event 12-19 23:35:53.548: D/OpenCV::camera(6226): CvCapture_Android::CvCapture_Android(0) 12-19 23:35:53.548: D/OpenCV::camera(6226): Library name: libopencv_java.so 12-19 23:35:53.548: D/OpenCV::camera(6226): Library base address: 0x82000000 12-19 23:35:53.552: D/OpenCV::camera(6226): Libraries folder found: /data/data/org.opencv.engine/lib/ 12-19 23:35:53.552: D/OpenCV::camera(6226): CameraWrapperConnector::connectToLib: folderPath=/data/data/org.opencv.engine/lib/ 12-19 23:35:53.552: E/OpenCV::camera(6226): ||libnative_camera_r4.0.3.so 12-19 23:35:53.552: E/OpenCV::camera(6226): ||libnative_camera_r2.2.0.so 12-19 23:35:53.552: E/OpenCV::camera(6226): ||libnative_camera_r4.2.0.so 12-19 23:35:53.552: E/OpenCV::camera(6226): ||libnative_camera_r4.1.1.so 12-19 23:35:53.552: E/OpenCV::camera(6226): ||libnative_camera_r3.0.1.so 12-19 23:35:53.552: E/OpenCV::camera(6226): ||libnative_camera_r4.0.0.so 12-19 23:35:53.552: E/OpenCV::camera(6226): ||libnative_camera_r2.3.3.so 12-19 23:35:53.552: D/OpenCV::camera(6226): try to load library 'libnative_camera_r4.2.0.so' 12-19 23:35:53.556: D/OpenCV::camera(6226): CameraWrapperConnector::connectToLib ERROR: cannot dlopen camera wrapper library /data/data/org.opencv.engine/lib ...

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2012-12-20 01:26:16 -0600 commented answer Android OpenCV support

Hi, Karthi. I met exactly the same problem that you mentioned. I'm using a Galaxy S1 for the testing. Have you found the solution already?
2012-12-20 01:22:20 -0600 commented question Device not found. Camera not supported.

I'm testing Sample2NativeCamera on a real device Galaxy S1, and unfortunately, I've got exactly the same problem as you mentioned here. Did u solve the problem already? If so, how?

Thanks Pei
2012-12-20 01:22:08 -0600 answered a question Device not found. Camera not supported.

I'm testing Sample2NativeCamera on a real device Galaxy S1, and unfortunately, I've got exactly the same problem as you mentioned here. Did u solve the problem already? If so, how?

Thanks Pei
2012-12-03 16:59:33 -0600 asked a question Failed to build OpenCV-2.4.3 on Raspberry Pi

Hi, all:

I failed to build opencv-2.4.3 on raspberry pi, the error messages:

[ 73%] Building CXX object modules/gpu/CMakeFiles/opencv_perf_gpu.dir/perf/perf_imgproc.cpp.o

Please submit a full bug report, with preprocessed source if appropriate. See <file: usr="" share="" doc="" gcc-4.6="" readme.bugs=""> for instructions. make[2]: * [modules/gpu/CMakeFiles/opencv_perf_gpu.dir/perf/perf_imgproc.cpp.o] Error 4 make[2]: Leaving directory '/home/pi/Download/OpenCV-2.4.3/build' make[1]: [modules/gpu/CMakeFiles/opencv_perf_gpu.dir/all] Error 2 make[1]: Leaving directory '/home/pi/Download/OpenCV-2.4.3/build' make:** [all] Error 2

Cheers Pei
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