Samples would be of great help about javacv HOT 19 CLOSED

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

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

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

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

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.

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...

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

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

Samuel

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

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.

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.

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

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

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

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.

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

[deleted comment]

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

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