Karthik's profile - activity

Yes..It resizes properly.... if I give the interpolation option as INTER_NEAREST or INTER_LINEAR... if i use INTER_CUBIC , there are several negative values in the resized matrix whereas I had all positive values in the original matrix..... Do you know why INTER_CUBIC generates negative float values in resized matrix.... I still used it for an Image(uchar) and got the resized image pretty well

No...aftr processing there will be floating values in Mat.... You manually assign certain pixels with float values such as 21.11,19.33,88.43 and then resize ...and display...do you get same result???

@Nyenna Did you use Float Mat ??? I think,imshow function supports only CV_8UC1 ..

@berak All values in res_B are 100.... But after processing B contains several floating point nos... In the resized Mat res_B it is not !!

I have a Mat object of type CV_32FC1 of size 300x300 ....

I tried :

B=Mat::ones(rows,cols,CV_32FC1)*100;

...process B...

Mat res_B=Mat::zeros(480,640,CV_32FC1); 

resize(B, res_B, Size(640,480), 0, 0, INTER_CUBIC);

How to resize it to size 640x480 ?? When I used the resize() function in OpenCV it doesnt seem to work...Any suggestions??

Thank you Guanta. I think shape matching is a good idea... I ll try it soon... Any OpenCV links for that?

I have two images which are taken from different positions. The 2nd camera is located to the right,up and backward with respect to 1st camera. So I think there is a perpective transformation between the two and not just affine transform since camera are at relatively different depths (am I right ??) I have few corresponding points between the two images. I think of using these corresponding points to determine the transformation of each pixel point from 1st to 2nd image.

I am confused by the functions findFundamentalMat and findHomography.... both return 3x3 matrix, what is the difference between the two ??

Is there any condition required/prerequisite to use them (when to use them)??

Which one to use to transform points from 1st image to 2nd image?? In the 3x3 matrices which the functions return, do they include the rotation and translation between the two image frames??

From wikipedia, came to kmnow that Fundamental matrix is relation between corresponding image points. In an SO answer here, it is said Essential Matrix E is required to get corresponding points... but I do not have the internal Camera matrix to calculate E.....I just have the two images.

How should I proceed to determine the corresponding point? Awaiting for suggestions.. Thank you

1. I have a processed binary image of dimension 300x300. This processed image contains few object(person or vehicle).

1. I also have another RGB image of the same scene of dimensiion 640x480. It is taken from a different position

note : both cameras are not the same

I can detect objects to some extent in the first image using background subtraction. I want to detect corresponding objects in the 2nd image. I went through opencv functions

• getAffineTransform
• getPerspectiveTransform
• findHomography
• estimateRigidTransform

All these functions require corresponding points(coordinates) in two images

In the 1st binary image, I have only the information that an object is present,it does not have features exactly similar to second image(RGB).

I thought conventional feature matching to determine corresponding control points which could be used to estimate the transformation parameters is not feasible because I think I cannot determine and match features from binary and RGB image(am I right??).

If I am wrong, what features could I take, how should I proceed with Feature matching, find corresponding points, estimate the transformation parameters.

The solution which I tried more of Manual marking to estimate transformation parameters(please correct me if I am wrong)

Note : There is no movement of both cameras.

• Manually marked rectangles around objects in processed image(binary)
• Noted down the coordinates of the rectangles
• Manually marked rectangles around objects in 2nd RGB image
• Noted down the coordinates of the rectangles
• Repeated above steps for different samples of 1st binary and 2nd RGB images

Now that I have some 20 corresponding points, I used them in the function as :

findHomography(src_pts, dst_pts, 0) ;

So once I detect an object in 1st image,

• I drew a bounding box around it,
• Transform the coordinates of the vertices using the above found transformation,

• finally draw a box in 2nd RGB image with transformed coordinates as vertices.

  But this doesnt mark the box in 2nd RGB image exactly over the person/object. Instead it is drawn somewhere else. Though I take several sample images of binary and RGB and use several corresponding points to estimate the transformation parameters, it seems that they are not accurate enough..

What are the meaning of CV_RANSAC and CV_LMEDS option, ransacReprojecThreshold and how to use them?

Is my approach good...what should I modify/do to make the registration accurate?

Any alternative approach to be used?

1- Create a symbolic link to /opt/ros/fuerte/lib/pkgconfig/opencv.pc inside the directory /user/local/lib/pkgconfig.

cd /usr/local/lib/pkgconfig

ln -s /opt/ros/fuerte/lib/pkgconfig/opencv.pc opencv.pc

2- Create the appropriate .pro file for your Qt project

TARGET= MyQtProject

TEMPLATE = APP

SOURCES += main.cpp

CONFIG += link_pkgconfig

PKGCONFIG += opencv

I have OpenCV2.4.2 installed as part of ROS(Fuerte) in my computer. I want to use an IDE for my projects, I already have installed Qt creator from Ubuntu Software center.

Can somebody help me with how to set up/configure Qt creator with the ROS opencv ?

Thank you

Hello everyone,

I am a beginner in OpenCV. I worked in matlab earlier. I have downloaded the opencv library 2.4.2 and I have no idea on how to build library files, etc. I have also downloaded and installed Microsoft Visual C++ 2010 Express. Please guide me with step by step procedure to do all the stuff and begin my project.

I am using Windows 7 64 bit.

Thank you in advance