Installing OpenCV for Java on Ubuntu 10.04

In this article I discuss how I set up OpenCV with Java on my Ubuntu 10.04. Primarily, I followed the process described at http://ubaa.net/shared/processing/opencv/ but with several changes (when I was stuck in the middle due to the old version used in the installation at the site). 

First, I installed OpenCV on Ubuntu using sudo apt-get install libcv-dev

Then, I put the openCV wrapper files known as "Processing OpenCV Library" from (this is the version that worked on my installation):

http://ubaa.net/shared/processing/opencv/download/2.0/beta/opencv-linux_2.0b.tar.gz

in a dir1 and then added to my JVM options java extensions directory as specified on the Processing page: -Djava.ext.dirs=dir1

I also had to install libcvaux-dev to resolve some link errors: sudo apt-get install libcvaux-dev.   

For the Face Detection to work, I had to set the cascade using OpenCV::cascade function before the OpenCV::detect call. After this, the example FaceDetection.java worked for me.

Sometime soon I needed the class file for PImage at run time. For this, I downloaded Processing from http://processing.org/download/processing-1.1.tgz. Then I put the directory containing core.jar (dir2) also in the java extensions setting above. That is,
-Djava.ext.dirs=dir1:dir2

Linux: Commands Used for Deprecating ConditionType etc

I had to rename ConditionType to ConditionType_Deprecated, and similarly for ConditionInstance, ContributionType and ContributionInstance.

I did the following:

find . \( -name "*.h" -or -name "*.cpp" \) | xargs sed -i "s/ConditionInstance/ConditionInstance_Deprecated/g"

But then the header file inclusions were also renamed. To undo these:

find . \( -name "*.h" -or -name "*.cpp" \) | xargs sed -i "s/ConditionInstance_Deprecated\.h/ConditionInstance.h/g"

Neither do we wanted the name changes for the functions with names like getConditionInstance. These had to be undone too.

draw line arrows in inkscape

Useful information here:

http://zzlinux.blogspot.com/2005/10/draw-line-arrows-in-inkscape.html

In short, you need to select line > fill and stroke > stroke style. 

My gdbinit file

set print pretty on
set print object on
set print static-members on
set print vtbl on
set print demangle on
set demangle-style gnu-v3

python
import sys
sys.path.insert(0, '/home/amit/downloads/gdb_printers/python')
from libstdcxx.v6.printers import register_libstdcxx_printers
register_libstdcxx_printers (None)
end
#source ~/bin/gdbinit_stl
#source ~/bin/gdbinit_boost

Ubuntu Update to 10.04

Every time I upgrade the Ubuntu version, I am faced with one or more issues. This time the audio and video worked fine and the desktop looks are much improved. The bootup is much faster. There is a new chat interface integrated with the desktop, which is cool, as is Ubuntu One.

However I faced the following issues. I upgraded on my desktop computer as well as my laptop -- so the list of issues is a merged list of the issues with both the laptop and the desktop.

1. gcc compile output messages miss the names of the variables after the upgrade. After a lot of failed google searches, I set LANG="" as described here. This set the problem right. 
2. There were problems with the windows borders missing. I read on the net this was due to compiz not starting. I added compiz into "Startup Applications" and rebooted for this to work. 
3. Installing KDevelop was a pain as the package has been removed from the repository. I followed this.

This has been the list in 3 days after the update. I will update this list as I find new problems.

UML Reverse Engineering Tools for C++ on Linux

I am looking for a UML tool for Ubuntu. It should be able to import C++ code.

I heard good reviews about Umbrello on the net. I installed Umbrello on my Ubuntu laptop. However at the time of writing, it is too slow/hangs with a high CPU usage. Due to lack of time, I won't be able to reopen a closed bug in this regard.

I have previously used ArgoUML, which I tried again. But its C++ import feature is not fully implemented.

UMLGraph takes a specification of classes to generate UML diagrams. In this aspect, UMLGraph is like Graphviz, but Graphviz is a more general diagramming tool. UMLGraph is good for java syntax.

StarUML (Wine) had issues with functioning mainly because it was running on wine.

BOUML provides C++ import and code generation. It allows users to place various components into the diagram manually. Then, for example in a class diagram, I can select the classes I want and view them. Thanks to the creator Bruno Pagès for his comments. 

find + xargs problem with whitespaces

Problem with spaces in filenames? Use null character for the output of find:

find /tmp/space* -print0 | xargs -0 grep "hello"