05 February 2010

RoboRealm Vision Processing - Wrappers Classes

I've been working with RoboRealm over the last week. It is a vision processing application. One of its nice features is being able to access it from another program. You can let it do the heavy lifting of extracting information from a web cam image and then your program just gets a few important data points for analysis.

The module I've been working with is Center of Gravity which locates a blob in the image and reports its size and location. In particular, I'm looking for a red circle.

The interface I've used is the RR_API which is a XML over a socket connection. Reading a single variable is straightforward but reading multiple variables with one request is a lot of detail chasing. I hate chasing details over and over again. That is why they originally created subroutines and, more recently, classes. So I wrote some classes to wrap the read variable routines. I haven't need to write information, yet, so that will wait until needed.

The files are in Google Code.

Individual variables are handled through the RoboRealmVar class and its base class RoboRealmVarBase. The base class is needed to provide an interface for reading multiple variables. More on that below.

RoboRealmVar is a template class to allow for handling different data types. One of the details with th RR interface is all data is returned as a char string so it has to be converted to the correct data type. The class handles that automatically. The header file has instances of the template for int, float, and string. Other types could be added but may need a char* to data type conversion routine. See the string instantiation for how that is done.

Variables are declared by:

rrIntVar mCogX;
rrIntVar mCogBoxSize;
rrIntVar mImageWidth
;

The examples are all class members, hence the prefix 'm' on their names.

Initialize the variables with the instance of the RR class. In the example mRoboRealm is the instance of RR opened through RR_API:

mCogX("COG_X", mRoboRealm),
mImageWidth("IMAGE_WIDTH", mRoboRealm),
mCogBoxSize("COG_BOX_SIZE", mRoboRealm),


and then read them using an overload of operator():

int cogx = mCogX();

Multiple variables are read using the RoboRealmVars class. Declare it and instantiate it with:

RoboRealmVars mCogVars;
mCogVars(mRoboRealm)

Again, my examples are from inside a class.

Then add the individual variables to the list by:

mCogVars.add(mCogX);
mCogVars.add(mImageWidth);
mCogVars.add(mCogBoxSize);

then read them through:

mCogVars();

You can access their values just as shown above through the individual variables.

Hopefully this will be useful to others.