Ask Your Question

njaa's profile - activity

2019-10-21 15:57:07 -0500 received badge  Notable Question (source)
2019-06-10 20:00:53 -0500 received badge  Notable Question (source)
2017-04-06 23:33:14 -0500 received badge  Taxonomist
2017-03-28 07:57:15 -0500 received badge  Popular Question (source)
2016-06-16 16:06:16 -0500 received badge  Popular Question (source)
2014-03-02 08:07:11 -0500 received badge  Nice Answer (source)
2012-12-12 18:59:12 -0500 asked a question Stereo Calibration (HTC Evo 3D)

Hi,

I try to calibrate the stereo camera of my Evo 3D. Therefore I use the stereo_calib.cpp sample and a set of stereo images:

Left:

image description

Right:

image description

Result:

image description

But as you can see the result is weird. When I use the sample images everything works fine:

image description

image description

image description

Somebody can tell me what I'm doing wrong? The images are of size 270x480 while the sample images are 480x640. Could this be a problem? And of course the quality of the second image is worse (HTC Evo problem). But for me it seems there is a general problem. Please help :)

2012-11-16 06:03:54 -0500 received badge  Scholar (source)
2012-11-14 06:07:21 -0500 asked a question Calculate histogram along line

Hi,

I have a binary image and I would like to determine the amount of white pixels along different angles. Let`s say the starting Point (F) is at the middle of the bottom row. Based on this 0° means all white pixels to the right of F and 180° means all white pixels to the left of F in the bottom row. So at the end I would like to have a histogram with x-axis holding the angle (from 0 to 180) and y-axis the number of white pixels.

Is this possible with the OpenCV calcHistogram function? Or do you have any idea how to do this efficiently?

Hope you understand the problem since I`m not allowed(?) to attach images here.

Thank you.

2012-09-24 03:17:44 -0500 received badge  Teacher (source)
2012-09-21 14:33:21 -0500 answered a question Inverse Perspective Mapping

push :)

No Computer Vision experts here?

2012-09-21 14:31:14 -0500 answered a question Unresolved inclusions in OpenCV android tutorial 4.

I had the same errors, but I don't know anymore how I solved it.

But these are my current settings which do work:

In the Project Properties:

  • Android -> Add the OpenCV Library
  • C/C++ build -> build command -> ${NDKROOT}/ndk-build (in Windows it's ndk-build.cmd I think)
  • C/C++ -> Environment -> add NDKROOT
  • C/C++ General -> Paths and Symbols -> Add the following:

    1. ${NDKROOT}/sources/cxx-stl/gnu-libstdc++/libs/armeabi-v7a/include
    2. ${NDKROOT}/sources/cxx-stl/gnu-libstdc++/include
    3. ${ProjDirPath}/../../sdk/native/jni/include
    4. ${NDKROOT}/platforms/android-9/arch-arm/usr/include
2012-09-14 12:14:19 -0500 asked a question Inverse Perspective Mapping

Hi,

I would like to generate the birds eye view of an input image (given as Mat) with OpenCV. The intrinsic and extrinsic parameters of the camera are known.

Among other things I need to know the Viewpoint of the camera (l,h,d) and the viewing direction:

IPM.jpeg

So my question is how can I determine these parameters with the help of the known intrinsic and extrinsic parameters? Or have I to measure them otherwise?

Thank you.

2012-08-14 15:03:27 -0500 answered a question Native Camera Samples

Anybody out there who can use the native camera with HTC one X?

Edit: Using the Optimus 3D doesn't work as well. Though there is no error message, but the screen stays black...

2012-08-12 08:47:27 -0500 asked a question Native Camera Samples

I try to run one of the Sample Projects which uses the native Camera (e.g. Tutorial 2) with the HTC One X but it does not work. The following line:

mCamera = new VideoCapture(Highgui.CV_CAP_ANDROID);

in the code provides following log:

07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Cameras: (null)
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Picture Sizes: 320x240,480x480,640x368,640x480,800x600,1024x768,1280x720,1280x752,1280x960,1440x1080,1600x1200,1836x1080,1920x1080,2048x1152,2048x1360,2048x1536,2592x1456,2592x1520,2592x1920,2592x1944,2592x1952,3264x1840,3264x2448
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Picture Formats: jpeg,jfif,exif
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Preview Sizes: 176x144,320x240,352x288,480x480,640x480,704x576,720x408,720x480,720x576,768x432,800x448,960x720,1280x720,1280x752,1360x720,1920x1080,1920x1088
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Preview Formats: yuv420p,yuv420sp
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Preview Frame Rates: 5,8,10,15,20,24,25,30
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Thumbnail Sizes: 0x0,320x240
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Whitebalance Modes: auto,incandescent,fluorescent,warm-fluorescent,daylight,cloudy-daylight,shade,twilight
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Effects: mono,negative,none,posterize,sepia,aqua,solarize,nv-vivid,nv-emboss
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Scene Modes: auto,action,portrait,landscape,beach,fireworks,night,night-portrait,snow,sports,steadyphoto,sunset,theatre,barcode,candlelight,beauty-mode,background-blur,backlight-hdr,close-up,white-board,flowers
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Focus Modes: auto,infinity,macro,fixed,continuous-video,continuous-picture
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Antibanding Options: off,auto,50hz,60hz
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Flash Modes: auto,on,off,torch,red-eye
07-14 16:41:19.260: D/OpenCV_NativeCamera(17420): initCameraConnect: autofocus is set to mode "continuous-video"
07-14 16:41:19.260: D/OpenCV_NativeCamera(17420): initCameraConnect: preview format is set to yuv420sp
07-14 16:41:19.260: A/libc(17420): **Fatal signal 11 (SIGSEGV) at 0x0000000c (code=1)**

I tested several other device and they curiously work. How can I solve this?

My device: HTC One X (Tegra 3), OS Version 4.0.3

2012-07-17 08:39:58 -0500 received badge  Famous Question (source)
2012-07-16 08:50:21 -0500 commented answer Installing Sample App / OpenCV Manager

The problem is that the redirection to the Play Store doesn't work ("Item not found"). So I cannot let the Manager download the latest package and I have to search for it manually. I'll try the neon-package then, thx

2012-07-16 02:08:22 -0500 received badge  Notable Question (source)
2012-07-14 15:20:00 -0500 commented answer Installing Sample App / OpenCV Manager

Thanks for the answer. Yes, I have installed the same apps now. The sample projects which do not use native camera work for me, just tutorial 2, facedetection, puzzle-15, etc. crash :/

2012-07-14 15:16:47 -0500 received badge  Popular Question (source)
2012-07-14 13:32:06 -0500 received badge  Student (source)
2012-07-14 08:24:32 -0500 received badge  Editor (source)
2012-07-14 08:05:44 -0500 asked a question Installing Sample App / OpenCV Manager

Hello,

I would like to install one of the advanced sample apps (let's say 15-puzzle) on my device (HTC One X), but I'm facing an annoying problem.

So I install the app (from eclipse or via google store) and at start up it asks for installing the OpenCV Manager. That works without problems! But then I have to install the OpenCV library package. Doing this, the Play Store opens and I get the message "Item not found". This happens all the time.

So anybody knows how to avoid this? Is there a possibility to load the packages from another source?

Thanks in advance!

Edit1: I have downloaded OCV 2.4 pack armeabi directly from the Play store and now it works :) Is this the right one or should I use "OCV 2.4 pack armeabi-v7a" or "OCV 2.4 pack armeabi-v7a neon"?

Edit2: Ok, still doesn't work. The native OpenCV camera leads to a crash.

this line: mCamera = new VideoCapture(Highgui.CV_CAP_ANDROID);

provides following log:

07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Cameras: (null)
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Picture Sizes: 320x240,480x480,640x368,640x480,800x600,1024x768,1280x720,1280x752,1280x960,1440x1080,1600x1200,1836x1080,1920x1080,2048x1152,2048x1360,2048x1536,2592x1456,2592x1520,2592x1920,2592x1944,2592x1952,3264x1840,3264x2448
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Picture Formats: jpeg,jfif,exif
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Preview Sizes: 176x144,320x240,352x288,480x480,640x480,704x576,720x408,720x480,720x576,768x432,800x448,960x720,1280x720,1280x752,1360x720,1920x1080,1920x1088
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Preview Formats: yuv420p,yuv420sp
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Preview Frame Rates: 5,8,10,15,20,24,25,30
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Thumbnail Sizes: 0x0,320x240
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Whitebalance Modes: auto,incandescent,fluorescent,warm-fluorescent,daylight,cloudy-daylight,shade,twilight
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Effects: mono,negative,none,posterize,sepia,aqua,solarize,nv-vivid,nv-emboss
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Scene Modes: auto,action,portrait,landscape,beach,fireworks,night,night-portrait,snow,sports,steadyphoto,sunset,theatre,barcode,candlelight,beauty-mode,background-blur,backlight-hdr,close-up,white-board,flowers
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Focus Modes: auto,infinity,macro,fixed,continuous-video,continuous-picture
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Antibanding Options: off,auto,50hz,60hz
07-14 16:41:19.250: D/OpenCV_NativeCamera(17420): Supported Flash Modes: auto,on,off,torch,red-eye
07-14 16:41:19.260: D/OpenCV_NativeCamera(17420): initCameraConnect: autofocus is set to mode "continuous-video"
07-14 16:41:19.260: D/OpenCV_NativeCamera(17420): initCameraConnect: preview format is set to yuv420sp
07-14 16:41:19.260: A/libc(17420): **Fatal signal 11 (SIGSEGV) at 0x0000000c (code=1)**

How can I solve this?

Edit3: I found a link with the same problem: thread.

My device: Tegra 3, OS Version 4.0.3, API 15 Installed Packages OCV 2.4 pack armeabi, 2.4 ... (more)