Samples would be of great help

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Hi Samuel,
thanks for your efforts with JavaCV.
Since me and a lot of other programmers are not very much familiar with
OpenCV, I would appreciate a few samples showing how e.g. the cvFindFace
function works.

Cheers,
Martin

Original issue reported on code.google.com by martin.h...@gmail.com on 12 Mar 2010 at 11:24

[GoogleCodeExporter]

Hello,

Sorry for not replying earlier. Apparently, by default, Google Code does not 
notify
project owners about new issues... I will have to figure out how to use this 
system
properly..

In any case, yes samples, documentation, etc. would be nice. I am not sure 
if/when I
will get around this, but one I idea I just had would be to port to Java the 
samples
in C from OpenCV. It shouldn't be too hard. 

BTW, if anyone creates samples they would like to check in the JavaCV 
repository, let
me know

Samuel

Original comment by samuel.a...@gmail.com on 20 Mar 2010 at 7:45

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Hi Samuel

I was trying the first example in your quickstart and I had this error when 
running
it in netbeans 6.8 on my 32-bit x86 CPU:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (0xe06d7363), pid=444, tid=1200
#
# JRE version: 6.0_18-b07
# Java VM: Java HotSpot(TM) Client VM (16.0-b13 mixed mode, sharing windows-x86 
)
# Problematic frame:
# C  [kernel32.dll+0x12afb]
#
# An error report file with more information is saved as:
# C:\Documents and Settings\Agustin\My Documents\Uniandes\Desarrollo de 
aplicaciones
de realidad mixta\Taller4\hs_err_pid444.log
#
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#
OpenCV Error: Null pointer (NULL array pointer is passed) in unknown function, 
file
..\..\..\..\ocv\opencv\src\cxcore\cxarray.cpp, line 2376
Java Result: 1

I know you said "Concretely, this means you should try to recompile OpenCV 
without
SSE instructions before asking me why JavaCV crashes." But honestly I don't
understand what you are saying, I mean I just downloaded the
OpenCV-2.1.0-win32-vs2008.exe and installed it in the default directory on my 
windows
XP. I don't know what to do to solve this error. Can you help me? Thank you

Kind regards,

Agustin Conde

Original comment by condeagu...@gmail.com on 11 Apr 2010 at 10:26

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Are you sure a file named "test.png" existed in the current directory?

Original comment by samuel.a...@gmail.com on 12 Apr 2010 at 4:57

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Hi,
You make an amazing work and I'm glad to see someone trying to get OpenCV in 
Java.
I have the same problem as the others. I can't make it working: I think we 
definitely
need more documentations. When it crashes, I can't debug anything and the error
message doesn't mean anything for me:
* OpenCV Error: Unspecified error (The node does not represent a user object 
(unknown
type?)) in cvRead, file C:\User\VP\ocv\opencv\src\cxcore\cxpersistence.cpp, 
line 4722
=====> c:\User doesn't exist on my computer.

I tried every samples given on this site, nothing works for me :-(. I have Win 
XP
32b, OpenCV 2.0 installed and my Eclipse project is configured as you 
described. It
would be really nice to get a quickstart that may start on any machine.

I hope you can find time to write some documentation soon.
Kind regards,
Alexandre

Original comment by alexandr...@gmail.com on 20 Apr 2010 at 6:30

[GoogleCodeExporter]

The new Test2 sample from the README.txt file should work on any machine... 
Since you
are using OpenCV 2.0 on 32-bit x86, your problems are most likely related to 
SSE,
also clearly indicated in the README.txt file.

Original comment by samuel.a...@gmail.com on 21 Apr 2010 at 4:45

[GoogleCodeExporter]

I experienced a similar issue when using cvLoad and solved it by inserting the
following lines before using it:

IplImage dummy = cvCreateImage(cvSize(1, 1), IPL_DEPTH_8U, 1);
cvErode(dummy, dummy, null, 1); 
dummy.release();

This seems to do some necessary initialisations...

Original comment by markus.l...@gmail.com on 21 Apr 2010 at 8:15

[GoogleCodeExporter]

Hi Samuel,
I read the README.txt file. In fact, it's not only SSE problems. I got a 
precompiled
version from here : http://code.google.com/p/pyopencv/downloads/list
So, SSE problems were solved for me, it's the reason I post my reply. I think 
the
problem is now there : http://opencv.willowgarage.com/wiki/FaceDetection (step 
11)
and now, I don't see any solution :-(.

Be sure that we understand you're doing an amazing job :-). Maybe can I help 
you to
write a documentation "How to make it works on Windows?" but for now, face 
detection
doesn't work (other functions work).

Kind regards, 
Alexandre

Original comment by alexandr...@gmail.com on 29 Apr 2010 at 7:18

[GoogleCodeExporter]

It works fine for my under Windows. If you have any specific problems, please 
provide
more details...

Samuel

Original comment by samuel.a...@gmail.com on 30 Apr 2010 at 2:04

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Ah, let me correct that... it /used/ to work fine under Windows, but I have just
tried it again and it didn't work anymore (giving me that darn cvLoad() error).
Moving the call to cvLoad() a bit later seems to fix it. The updated sample 
code on
the main page now works. (I will eventually update the README.txt file as 
well...)

Samuel

Original comment by samuel.a...@gmail.com on 30 Apr 2010 at 2:47

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Hello,

Would it be possible to have an example of individual pixel access? Since 
cvGet2D is not recommended.

I appreciate your efforts very much.

Regards,
Greg.

Original comment by supert...@gmail.com on 20 Nov 2010 at 3:32

[GoogleCodeExporter]

Just remembered to ask,  What would be more efficient for individual pixel 
access?  Should the whole image be converted to a BufferedImage and then access 
with  bufferedImage.getRGB(x, y);?  Would individually accessing through the 
jni interface be much more costly?

Greg.

Original comment by supert...@gmail.com on 20 Nov 2010 at 3:37

[GoogleCodeExporter]

Just access directly, the same as in C, the raw buffer returned by 
IplImage.getByteBuffer(), but obviously the syntax is a bit different in Java. 
You can find examples of this in the JavaCV.adaptiveBinarization() method here:
http://code.google.com/p/javacv/source/browse/trunk/javacv/src/com/googlecode/ja
vacv/JavaCV.java#310

Original comment by samuel.a...@gmail.com on 20 Nov 2010 at 3:53

• Changed state: Accepted

[GoogleCodeExporter]

Can you please give one simple example on how to use ARToolKitPlus in JavaCV. 
May be a page on wiki.

Original comment by dearaaka...@gmail.com on 2 Dec 2010 at 6:38

[GoogleCodeExporter]

I use it in the MarkerDetector class, so you could start by looking at this 
code:
http://code.google.com/p/javacv/source/browse/trunk/javacv/src/com/googlecode/ja
vacv/MarkerDetector.java

Original comment by samuel.a...@gmail.com on 2 Dec 2010 at 8:00

[GoogleCodeExporter]

Hi Samuel, thanks for your prompt reply.
I used your MarkerDetector class to detect markers but it always returns an 
array of Marker objects with length 0.
I tried using a camera stream and also this image: 
http://www.burncg.cn/burnblog/attachments/month_0903/t2009314114342.jpg

Any suggestions on what I might be doing wrong?

Thanks.

Original comment by dearaaka...@gmail.com on 4 Dec 2010 at 10:57

[GoogleCodeExporter]

I've hardcoded MarkerDetector to use BCH codes. To use templates, you'll need 
to change the line:
    setMarkerMode(t, MARKER_ID_BCH);
and load your templates using arLoadPatt() or something

BTW, can you post on the mailing list instead? This isn't not an issue with 
JavaCV, it's a question about how to use JavaCV, so you should post on the 
mailing list, thank you

Original comment by samuel.a...@gmail.com on 5 Dec 2010 at 10:28

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[deleted comment]

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This issue is about needing more JavaCV samples. If your comment has nothing to 
do with samples, please *DO NOT* post here, thank you

Original comment by samuel.a...@gmail.com on 5 Dec 2010 at 11:02

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Latest version adds a few samples. Changing status to "Done", but please reopen 
if you feel this is still a big issue.

Original comment by samuel.a...@gmail.com on 19 Feb 2011 at 3:52

• Changed state: Done