I am a beginner in openCV. I want to detect some images, do I need to generate cascade file similar to one present in face detection sample app? What is the correct way?

asked 2015-12-23 05:11:01 -0600

Priyanka Agarwal gravatar image

I have installed opencv-3.0.0 using the installer from "http://downloads.sourceforge.net/opencvlibrary/opencv-3.0.0.exe". I am running the utilities opencv_createsamples and opencv_traincascade directly after running the installer. Is this the correct way to run the utilities?

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"Is this the correct way to run the utilities?" - yes, i'd think so.

http://docs.opencv.org/ref/master/dc/...

http://answers.opencv.org/questions/q...

berak gravatar imageberak ( 2015-12-23 05:26:22 -0600 )edit

Thanks for the response Berak. Can you help me get the steps to generate a correct cascade file?

Priyanka Agarwal gravatar imagePriyanka Agarwal ( 2015-12-23 05:54:51 -0600 )edit

read a bit, try out, come back with actual problems ?

berak gravatar imageberak ( 2015-12-23 06:11:55 -0600 )edit

I tried generating a cascade file for detecting a car. I have 500 images in negative folder and one positive image. I used the below commands: 1. opencv_createsamples -img car.png -num 550 -w 48 -h 24 –vec cars.vec 2. 2. opencv_traincascade -data data -vec cars.vec -bg bg.txt -numStages 10 -minhitrate 0.999 -maxfalsealarm 0.1 -featureType LBP -numPos 1 -numNeg 500 -w 48 -h 24 3. I replaced the cascade file in face-detection sample app with this new generated cascade file.

But many false positives gets detected too along with the car. Probably the cascade file which I generated is not correct enough to detect only the car which I supplied as a positive image.

Priyanka Agarwal gravatar imagePriyanka Agarwal ( 2015-12-23 06:23:16 -0600 )edit

I am going through many other links and materials, but any suggestion will be of great help.

Priyanka Agarwal gravatar imagePriyanka Agarwal ( 2015-12-23 06:24:31 -0600 )edit

you're trying with one positive ( -img car.png) only ? that won't work. decide, which orientation(front,back,side) you want, it will only work for one. then use the annotation tool , and gather a few hundred positives

berak gravatar imageberak ( 2015-12-23 06:24:59 -0600 )edit

Thanks Berak. Yes I am trying with one positive, because my goal is to detect a particular image. Is that not possible with OpenCV?

Priyanka Agarwal gravatar imagePriyanka Agarwal ( 2015-12-23 06:28:47 -0600 )edit

a particular image ? what do you mean exactly ?

berak gravatar imageberak ( 2015-12-23 06:40:30 -0600 )edit

I have an image of a company's logo and now I want to detect it. This logo can be present anywhere, on top of any thing. As soon as I get this logo in my camera feed, I want to detect it and mark it.

Priyanka Agarwal gravatar imagePriyanka Agarwal ( 2015-12-23 06:43:38 -0600 )edit

so, that means, you need to collect images of your logo, not whole cars, right ? why didn't you say so before ?

still, you need as many cropped images of that logo as you can get. also, try to keep it as close to 1 orientation as possible.

berak gravatar imageberak ( 2015-12-23 06:49:38 -0600 )edit
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