OpenCV：训练级联分类器

Question

I am trying to train a cascade classifier using OpenCV, a tutorial & UIUC Image Database for Car Detection . However, the training 'hangs' at stage 0 and never generates any files; in the tutorial, results are seen in a matter of minutes.

I am running OpenCV 2.4.8, which I have installed using conda, on a 2015 MBP running Yosemite (10.10.5)

Steps:

1. Downloaded the dataset & saved the positive images in a pos folder and the negative images in a neg folder

2. generated a txt file for the positive images

   find pos -iname "*.pgm" > cars.txt sed -i '' 's/.pgm/.pgm 1 0 0 100 40/g' cars.txt

3. generated a txt file for the negative images

   find neg -iname "*.pgm" > bg.txt

4. generated a vec file from cars.txt

   opencv_createsamples -info cars.txt -num 550 -w 48 -h 24 -vec cars.vec

5. create a data dir

   mkdir data

6. train cascade

   opencv_traincascade -data data -vec cars.vec -bg bg.txt -numPos 500 -numNeg 500 -numStages 2 -w 48 -h 24 -featureType LBP

Output:

PARAMETERS:
cascadeDirName: data
vecFileName: cars.vec
bgFileName: bg.txt
numPos: 500
numNeg: 500
numStages: 2
precalcValBufSize[Mb] : 256
precalcIdxBufSize[Mb] : 256
stageType: BOOST
featureType: LBP
sampleWidth: 48
sampleHeight: 24
boostType: GAB
minHitRate: 0.995
maxFalseAlarmRate: 0.5
weightTrimRate: 0.95
maxDepth: 1
maxWeakCount: 100

===== TRAINING 0-stage =====
<BEGIN
POS count : consumed   500 : 500
NEG count : acceptanceRatio    500 : 1

I have waited for several hours but the training never progresses nor does it generate any files in my data directory. What is causing the 'hanging'?

Answer 1

For what it's worth, I ran into the same symptom and it was driving me crazy. Uninstalling and reinstalling opencv fixed it . The exact command that was hanging suddenly worked fine. It could be you have an old version of opencv lingering somewhere like I had:

$ brew uninstall opencv
Uninstalling /usr/local/Cellar/opencv/2.4.12... (225 files, 36M)
opencv 2.4.11_1 is still installed.
Remove them all with `brew uninstall --force opencv`.

$ brew uninstall --force opencv
Uninstalling opencv... (222 files, 35M)

$ brew install opencv --with-tbb

At any rate, something to consider.

Answer 2

I run into the same problem. It turns out using haar cascade training works just fine. You could specific more stages for it to improve accuracy.

Answer 3

I just don't see how you expect to get anything good out of two training stages. You should train until your -acceptanceRatioBreakValue reaches 10e-5. You've ordered 10 burgers from OpenCV but left after only getting 2.

See here: http://docs.opencv.org/3.1.0/dc/d88/tutorial_traincascade.html#gsc.tab=0

Answer 4

使用 --use-tbb （来自自制软件）编译 OpenCV 为我解决了这个问题，我相信这是 OS X 上 GCD 实现的一个错误，如下所述： https : //github.com/opencv/opencv/issues/4765